| 99 |
A Christmas hCard From Me To You |
So apparently Christmas is coming. And what is Christmas all about? Well, cleaning out your address book, of course! What better time to go through your contacts, making sure everyone’s details are up date and that you’ve deleted all those nasty clients who never paid on time?
It’s also a good time to make sure your current clients and colleagues have your most up-to-date details, so instead of filling up their inboxes with e-cards, why not send them something useful? Something like a… vCard! (See what I did there?)
Just in case you’ve been working in a magical toy factory in the upper reaches of Scandinavia for the last few years, I’m going to tell you that now would also be the perfect time to get into microformats. Using the hCard format, we’ll build a very simple web page and markup our contact details in such a way that they’ll be understood by microformats plugins, like Operator or Tails for Firefox, or the cross-browser Microformats Bookmarklet.
Oh, and because Christmas is all about dressing up and being silly, we’ll make the whole thing look nice and have a bit of fun with some CSS3 progressive enhancement.
If you can’t wait to see what we end up with, you can preview it here.
Step 1: Contact Details
First, let’s decide what details we want to put on the page. I’d put my full name, my email address, my phone number, and my postal address, but I’d rather not get surprise visits from strangers when I’m fannying about with my baubles, so I’m going to use Father Christmas instead (that’s Santa to you Yanks).
Father Christmas
fatherchristmas@elliotjaystocks.com
25 Laughingallthe Way
Snow Falls
Lapland
Finland
010 60 58 000
Step 2: hCard Creator
Now I’m not sure about you, but I rather like getting the magical robot pixies to do the work for me, so head on over to the hCard Creator and put those pixies to work! Pop in your details and they’ll give you some nice microformatted HTML in turn.
<div id="hcard-Father-Christmas" class="vcard">
<a class="url fn" href="http://elliotjaystocks.com/fatherchristmas">Father Christmas</a>
<a class="email" href="mailto:fatherchristmas@elliotjaystocks.com"> fatherchristmas@elliotjaystocks.com</a>
<div class="adr">
<div class="street-address">25 Laughingallthe Way</div>
<span class="locality">Snow Falls</span>
,
<span class="region">Lapland</span>
,
<span class="postal-code">FI-00101</span>
<span class="country-name">Finland</span>
</div>
<div class="tel">010 60 58 000</div>
<p style="font-size:smaller;">This <a href="http://microformats.org/wiki/hcard">hCard</a> created with the <a href="http://microformats.org/code/hcard/creator">hCard creator</a>.</p>
</div>
Step 3: Editing The Code
One of the great things about microformats is that you can use pretty much whichever HTML tags you want, so just because the hCard Creator Fairies say something should be wrapped in a <span> doesn’t mean you can’t change it to a <blink>. Actually, no, don’t do that. That’s not even excusable at Christmas.
I personally have a penchant for marking up each line of an address inside a <li> tag, where the parent url retains the class of adr. As long as you keep the class names the same, you’ll be fine.
<div id="hcard-Father-Christmas" class="vcard">
<h1><a class="url fn" href="http://elliotjaystocks.com/fatherchristmas">Father Christmas </a></h1>
<a class="email" href="mailto:fatherchristmas@elliotjaystocks.com?subject=Here, have some Christmas cheer!">fatherchristmas@elliotjaystocks.com</a>
<ul class="adr">
<li class="street-address">25 Laughingallthe Way</li>
<li class="locality">Snow Falls</li>
<li class="region">Lapland</li>
<li class="postal-code">FI-00101</li>
<li class="country-name">Finland</li>
</ul>
<span class="tel">010 60 58 000</span>
</div>
Step 4: Testing The Microformats
With our microformats in place, now would be a good time to test that they’re working before we start making things look pretty. If you’re on Firefox, you can install the Operator or Tails extensions, but if you’re on another browser, just add the Microformats Bookmarklet. Regardless of your choice, the results is the same: if you’ve code microformatted content on a web page, one of these bad boys should pick it up for you and allow you to export the contact info. Give it a try and you should see father Christmas appearing in your address book of choice. Now you’ll never forget where to send those Christmas lists!
Step 5: Some Extra Markup
One of the first things we’re going to do is put a photo of Father Christmas on the hCard. We’ll be using CSS to apply a background image to a div, so we’ll be needing an extra div with a class name of “photo”. In turn, we’ll wrap the text-based elements of our hCard inside a div cunningly called “text”. Unfortunately, because of the float technique we’ll be using, we’ll have to use one of those nasty float-clearing techniques. I shall call this “christmas-cheer”, since that is what its presence will inevitably bring, of course.
Oh, and let’s add a bit of text to give the page context, too:
<p>Send your Christmas lists my way...</p>
<div id="hcard-Father-Christmas" class="vcard">
<div class="text">
<h1><a class="url fn" href="http://elliotjaystocks.com/fatherchristmas">Father Christmas </a></h1>
<a class="email" href="mailto:fatherchristmas@elliotjaystocks.com?subject=Here, have some Christmas cheer!">fatherchristmas@elliotjaystocks.com</a>
<ul class="adr">
<li class="street-address">25 Laughingallthe Way</li>
<li class="locality">Snow Falls</li>
<li class="region">Lapland</li>
<li class="postal-code">FI-00101</li>
<li class="country-name">Finland</li>
</ul>
<span class="tel">010 60 58 000</span>
</div>
<div class="photo"></div>
<br class="christmas-cheer" />
</div>
<div class="credits">
<p>A tutorial by <a href="http://elliotjaystocks.com">Elliot Jay Stocks</a> for <a href="http://24ways.org/">24 Ways</a></p>
<p>Background: <a href="http://sxc.hu/photo/1108741">stock.xchng</a> | Father Christmas: <a href="http://istockphoto.com/file_closeup/people/4575943-active-santa.php?id=4575943">iStockPhoto</a></p>
</div>
Step 6: Some Christmas Sparkle
So far, our hCard-housing web page is slightly less than inspiring, isn’t it? It’s time to add a bit of CSS. There’s nothing particularly radical going on here; just a simple layout, some basic typographic treatment, and the placement of the Father Christmas photo. I’d usually use a more thorough CSS reset like the one found in the YUI or Eric Meyer’s, but for this basic page, the simple * solution will do.
Check out the step 6 demo to see our basic styles in place.
From this…
… to this:
Step 7: Fun With imagery
Now it’s time to introduce a repeating background image to the <body> element. This will seamlessly repeat for as wide as the browser window becomes.
But that’s fairly straightforward. How about having some fun with the Father Christmas image? If you look at the image file itself, you’ll see that it’s twice as wide as the area we can see and contains a ‘hidden’ photo of our rather camp St. Nick.
As a light-hearted visual… er… ‘treat’ for users who move their mouse over the image, we move the position of the background image on the “photo” div. Check out the step 7 demo to see it working.
Step 8: Progressive Enhancement
Finally, this fun little project is a great opportunity for us to mess around with some advanced CSS features (some from the CSS3 spec) that we rarely get to use on client projects. (Don’t forget: no Christmas pressies for clients who want you to support IE6!)
Here are the rules we’re using to give some browsers a superior viewing experience:
@font-face allows us to use Jos Buivenga’s free font ‘Fertigo Pro’ on all text;
text-shadow adds a little emphasis on the opening paragraph;
body > p:first-child causes only the first paragraph to receive this treatment;
border-radius created rounded corners on our main div and the links within it;
and webkit-transition allows us to gently fade in between the default and hover states of those links.
And with that, we’re done! You can see the results here. It’s time to customise the page to your liking, upload it to your site, and send out the URL. And do it quickly, because I’m sure you’ve got some last-minute Christmas shopping to finish off! |
2008 |
Elliot Jay Stocks |
elliotjaystocks |
2008-12-10T00:00:00+00:00 |
https://24ways.org/2008/a-christmas-hcard-from-me-to-you/ |
code |
| 293 |
A Favor for Your Future Self |
We tend to think about the future when we build things. What might we want to be able to add later? How can we refactor this down the road? Will this be easy to maintain in six months, a year, two years? As best we can, we try to think about the what-ifs, and build our websites, systems, and applications with this lens.
We comment our code to explain what we knew at the time and how that impacted how we built something. We add to-dos to the things we want to change. These are all great things! Whether or not we come back to those to-dos, refactor that one thing, or add new features, we put in a bit of effort up front just in case to give us a bit of safety later.
I want to talk about a situation that Past Alicia and Team couldn’t even foresee or plan for. Recently, the startup I was a part of had to remove large sections of our website. Not just content, but entire pages and functionality. It wasn’t a very pleasant experience, not only for the reason why we had to remove so much of what we had built, but also because it’s the ultimate “I really hope this doesn’t break something else” situation. It was a stressful and tedious effort of triple checking that the things we were removing weren’t dependencies elsewhere. To be honest, we wouldn’t have been able to do this with any amount of success or confidence without our test suite.
Writing tests for code is one of those things that developers really, really don’t want to do. It’s one of the easiest things to cut in the development process, and there’s often a struggle to have developers start writing tests in the first place. One of the best lessons the web has taught us is that we can’t, in good faith, trust the happy path. We must make sure ourselves, and our users, aren’t in a tough spot later on because we only thought of the best case scenarios.
JavaScript
Regardless of your opinion on whether or not everything needs to be built primarily with JavaScript, if you’re choosing to build a JavaScript heavy app, you absolutely should be writing some combination of unit and integration tests.
Unit tests are for testing extremely isolated and small pieces of code, which we refer to as the units themselves. Great for reused functions and small, scoped areas, this is the closest you examine your code with the testing microscope. For example, if we were to build a calculator, the most minute piece we could test could be the basic operations.
/*
* This example uses a test framework called Jasmine
*/
describe("Calculator Operations", function () {
it("Should add two numbers", function () {
// Say we have a calculator
Calculator.init();
// We can run the function that does our addition calculation...
var result = Calculator.addNumbers(7,3);
// ...and ensure we're getting the right output
expect(result).toBe(10);
});
});
Even though these teeny bits work in isolation, we should ensure that connecting the large pieces work, as well. This is where integration tests excel. These tests ensure that two or more different areas of code, that may not directly know about each other, still behave in expected ways. Let’s build upon our calculator - we may want the operations to be saved in memory after a calculation runs. This isn’t as suited for a unit test because there are a few other moving pieces involved in the process (the calculations, checking if the result was an error, etc.).
it(“Should remember the last calculation”, function () {
// Run an operation
Calculator.addNumbers(7,10);
// Expect something else to have happened as a result
expect(Calculator.updateCurrentValue).toHaveBeenCalled();
expect(Calculator.currentValue).toBe(17);
});
Unit and integration tests provide assurance that your hand-rolled JavaScript should, for the most part, never fail in a grand fashion. Although it still might happen, you could be able to catch problems way sooner than without a test suite, and hopefully never push those failures to your production environment.
Interfaces
Regardless of how you’re building something, it most definitely has some kind of interface. Whether you’re using a very barebones structure, or you’re leveraging a whole design system, these things can be tested as well.
Acceptance testing helps us ensure that users can get from point A to point B within our web things, which can provide assurance that major features are always functioning properly. By simulating user input and data entry, we can go through whole user workflows to test for both success and failure scenarios. These are not necessarily for simulating edge-case scenarios, but rather ensuring that our core offerings are stable.
For example, if your site requires signup, you want to make sure the workflow is behaving as expected - allowing valid information to go through signup, while invalid information does not let you progress.
/*
* This example uses Jasmine along with an add-on called jasmine-integration
*/
describe("Acceptance tests", function () {
// Go to our signup page
var page = visit("/signup");
// Fill our signup form with invalid information
page.fill_in("input[name='email']", "Not An Email");
page.fill_in("input[name='name']", "Alicia");
page.click("button[type=submit]");
// Check that we get an expected error message
it("Shouldn't allow signup with invalid information", function () {
expect(page.find("#signupError").hasClass("hidden")).toBeFalsy();
});
// Now, fill our signup form with valid information
page.fill_in("input[name='email']", "thisismyemail@gmail.com");
page.fill_in("input[name='name']", "Gerry");
page.click("button[type=submit]");
// Check that we get an expected success message and the error message is hidden
it("Should allow signup with valid information", function () {
expect(page.find("#signupError").hasClass("hidden")).toBeTruthy();
expect(page.find("#thankYouMessage").hasClass("hidden")).toBeFalsy();
});
});
In terms of visual design, we’re now able to take snapshots of what our interfaces look like before and after any code changes to see what has changed. We call this visual regression testing. Rather than being a pass or fail test like our other examples thus far, this is more of an awareness test, intended to inform developers of all the visual differences that have occurred, intentional or not. Developers may accidentally introduce a styling change or fix that has unintended side effects on other areas of a website - visual regression testing helps us catch these sooner rather than later. These do require a bit more consistent grooming than other tests, but can be valuable in major CSS refactors or if your CSS is generally a bit like Jenga.
Tools like PhantomCSS will take screenshots of your pages, and do a visual comparison to check what has changed between two sets of images. The code would look something like this:
/*
* This example uses PhantomCSS
*/
casper.start("/home").then(function(){
// Initial state of form
phantomcss.screenshot("#signUpForm", "sign up form");
// Hit the sign up button (should trigger error)
casper.click("button#signUp");
// Take a screenshot of the UI component
phantomcss.screenshot("#signUpForm", "sign up form error");
// Fill in form by name attributes & submit
casper.fill("#signUpForm", {
name: "Alicia Sedlock",
email: "alicia@example.com"
}, true);
// Take a second screenshot of success state
phantomcss.screenshot("#signUpForm", "sign up form success");
});
You run this code before starting any development, to create your baseline set of screen captures. After you’ve completed a batch of work, you run PhantomCSS again. This will create a second batch of screenshots, which are then put through an image comparison tool to display any differences that occurred. Say you changed your margins on our form elements – your image diff would look something like this:
This is a great tool for ensuring not just your site retains its expected styling, but it’s also great for ensuring nothing accidentally changes in the living style guide or modular components you may have developed. It’s hard to keep eagle eyes on every visual aspect of your site or app, so visual regression testing helps to keep these things monitored.
Conclusion
The shape and size of what you’re testing for your site or app will vary. You may not need lots of unit or integration tests if you don’t write a lot of JavaScript. You may not need visual regression testing for a one page site. It’s important to assess your codebase to see which tests would provide the most benefit for you and your team.
Writing tests isn’t a joy for most developers, myself included. But I end up thanking Past Alicia a lot when there are tests, because otherwise I would have introduced a lot of issues into codebases. Shipping code that’s broken breaks trust with our users, and it’s our responsibility as developers to make sure that trust isn’t broken. Testing shouldn’t be considered a “nice to have” - it should be an integral piece of our workflow and our day-to-day job. |
2016 |
Alicia Sedlock |
aliciasedlock |
2016-12-03T00:00:00+00:00 |
https://24ways.org/2016/a-favor-for-your-future-self/ |
code |
| 75 |
A Harder-Working Class |
Class is only becoming more important. Focusing on its original definition as an attribute for grouping (or classifying) as well as linking HTML to CSS, recent front-end development practices are emphasizing class as a vessel for structured, modularized style packages. These patterns reduce the need for repetitive declarations that can seriously bloat file sizes, and instil human-readable understanding of how the interface, layout, and aesthetics are constructed.
In the next handful of paragraphs, we will look at how these emerging practices – such as object-oriented CSS and SMACSS – are pushing the relevance of class. We will also explore how HTML and CSS architecture can be further simplified, performance can be boosted, and CSS utility sharpened by combining class with the attribute selector.
A primer on attribute selectors
While attribute selectors were introduced in the CSS 2 spec, they are still considered rather exotic. These well-established and well-supported features give us vastly improved flexibility in targeting elements in CSS, and offer us opportunities for smarter markup. With an attribute selector, you can directly style an element based on any of its unique – or uniquely shared – attributes, without the need for an ID or extra classes. Unlike pseudo-classes, pseudo-elements, and other exciting features of CSS3, attribute selectors do not require any browser-specific syntax or prefix, and are even supported in Internet Explorer 7.
For example, say we want to target all anchor tags on a page that link to our homepage. Where otherwise we might need to manually identify and add classes to the HTML for these specific links, we could simply write:
[href=index.html] { }
This selector reads: target every element that has an href attribute of “index.html”.
Attribute selectors are more faceted, though, as they also give us some very simple regular expression-like logic that helps further narrow (or widen) a selector’s scope. In our previous example, what if we wanted to also give indicative styles to any anchor tag linking to an external site? With no way to know what the exact href value would be for every external link, we need to use an expression to match a common aspect of those links. In this case, we know that all external links need to start with “http”, so we can use that as a hook:
[href^=http] { }
The selector here reads: target every element that has an href attribute that begins with “http” (which will also include “https”). The ^= means “starts with”. There are a few other simple expressions that give us a lot of flexibility in targeting elements, and I have found that a deep understanding of these and other selector types to be very useful.
The class-attribute selector
By matching classes with the attribute selector, CSS can be pushed to accomplish some exciting new feats. What I call a class-attribute selector combines the advantages of classes with attribute selectors by targeting the class attribute, rather than a specific class. Instead of selecting .urgent, you could select [class*=urgent]. The latter may seem like a more verbose way of accomplishing the former, but each would actually match two subtly different groups of elements.
Eric Meyer first explored the possibility of using classes with attribute selectors over a decade ago. While his interest in this technique mostly explored the different facets of the syntax, I have found that using class-attribute selectors can have distinct advantages over either using an attribute selector or a straightforward class selector.
First, let’s explore some of the subtleties of why we would target class before other attributes:
Classes are ubiquitous. They have been supported since the HTML 4 spec was released in 1999. Newer attributes, such as the custom data attribute, have only recently begun to be adopted by browsers.
Classes have multiple ways of being targeted. You can use the class selector or attribute selector (.classname or [class=classname]), allowing more flexible specificity than resorting to an ID or !important.
Classes are already widely used, so adding more classes will usually require less markup than adding more attributes.
Classes were designed to abstractly group and specify elements, making them the most appropriate attribute for styling using object-oriented methods (as we will learn in a moment).
Also, as Meyer pointed out, we can use the class-attribute selector to be more strict about class declarations. Of these two elements:
<h2 class="very urgent">
<h2 class="urgent">
…only the second h2 would be selected by [class=urgent], while .urgent would select both. The use of = matches any element with the exact class value of “urgent”. Eric explores these nuances further in his series on attribute selectors, but perhaps more dramatic is the added power that class-attribute selectors can bring to our CSS.
More object-oriented, more scalable and modular
Nicole Sullivan has been pushing abstracted, object-oriented thinking in CSS development for years now. She has shared stacks of knowledge on how behemoth sites have seen impressive gains in maintenance overhead and CSS file sizes by leaning heavier on classes derived from common patterns. Jonathan Snook also speaks, writes and is genuinely passionate about improving our markup by using more stratified and modular class name conventions. With SMACSS, he shows this to be highly useful across sites – both complex and simple – that exhibit repeated design patterns. Sullivan and Snook both push the use of class for styling over other attributes, and many front-end developers are fast advocating such thinking as best practice.
With class-attribute selectors, we can further abstract our CSS, pushing its scalability. In his chapter on modules, Snook gives the example of a .pod class that might represent a certain set of styles. A .pod style set might be used in varying contexts, leading to CSS that might normally look like this:
.pod { }
form .pod { }
aside .pod { }
According to Snook, we can make these styles more portable by targeting more verbose classes, rather than context:
.pod { }
.pod-form { }
.pod-sidebar { }
…resulting in the following HTML:
<div class="pod">
<div class="pod pod-form">
<div class="pod pod-sidebar">
This divorces the <div>’s styles from its context, making it applicable to any situation in which it is needed. The markup is clean and portable, and the classes are imbued with meaning as to what module they belong to.
Using class-attribute selectors, we can simplify this further:
[class*=pod] { }
.pod-form { }
.pod-sidebar { }
The *= tells the browser to look for any element with a class attribute containing “pod”, so it matches “pod”, “pod-form”, “pod-sidebar”, etc. This allows only one class per element, resulting in simpler HTML:
<div class="pod">
<div class="pod-form">
<div class="pod-sidebar">
We could further abstract the concept of “form” and “sidebar” adjustments if we knew that each of those alterations would always need the same treatment.
/* Modules */
[class*=pod] { }
[class*=btn] { }
/* Alterations */
[class*=-form] { }
[class*=-sidebar] { }
In this case, all elements with classes appended “-form” or “-sidebar” would be altered in the same manner, allowing the markup to stay simple:
<form>
<h2 class="pod-form">
<a class="btn-form" href="#">
<aside>
<h2 class="pod-sidebar">
<a class="btn-sidebar" href="#">
50+ shades of specificity
Classes are just powerful enough to override element selectors and default styling, but still leave room to be trumped by IDs and !important styles. This makes them more suitable for object-oriented patterns and helps avoid messy specificity issues that can not only be a pain for developers to maintain, but can also affect a site’s performance. As Sullivan notes, “In almost every case, classes work well and have fewer unintended consequences than either IDs or element selectors”. Proper use of specificity and cascade is crucial in building straightforward, efficient CSS.
One interesting aspect of attribute selectors is that they can be compounded for increasing levels of specificity. Attribute selectors are assigned a specificity level of ten, the same as class selectors, but both class and attribute selectors can be chained together, giving them more and more specificity with each link. Some examples:
.box { }
/* Specificity of 10 */
.box.promo { }
/* Specificity of 20 */
[class*=box] { }
/* Specificity of 10 */
[class*=box][class*=promo] { }
/* Specificity of 20 */
You can chain both types together, too:
.box[class*=promo] { }
/* Specificity of 20 */
I was amused to find, though, that you can chain the exact same class and attribute selectors for infinite levels of specificity
.box { }
/* Specificity of 10 */
.box.box { }
/* Specificity of 20 */
.box.box.box { }
/* Specificity of 30 */
[class*=box] { }
/* Specificity of 10 */
[class*=box][class*=box] { }
/* Specificity of 20 */
[class*=box][class*=box][class*=box] { }
/* Specificity of 30 */
.box[class*=box].box[class*=box] { }
/* Specificity of 40 */
To override .box styles for promo, we wouldn’t need to add an ID, change the order of .promo and .box in the CSS, or resort to an !important style. Granted, any issue that might need this fine level of specificity tweaking could probably be better solved with clever cascades, but having options never hurts.
Smarter CSS
One of the most powerful aspects of the class-attribute selector is its ability to expand the simple logic found in CSS. When developing Gridset (an online tool for building grids and outputting them as CSS), I realized that with the right class name conventions, class-attribute selectors would allow the CSS to be smart enough to automatically adjust for column offsets without the need for extra classes. This imbued the CSS output with logic that other frameworks lacked, and makes a developer’s job much easier.
Say you need an element that spans column five (c5) to column six (c6) on your grid, and is preceded by an element spanning column one (c1) to column three (c3). The CSS can anticipate such a scenario:
.c1-c3 + .c5-c6 {
margin-left: 25%; /* …or the width of column four plus two gutter widths */
}
…but to accommodate all of the margin offsets that could span that same gap, we would need to write a rather protracted list for just a six column grid:
.c1-c3 + .c5-c6,
.c1-c3 + .c5,
.c2-c3 + .c5-c6,
.c2-c3 + .c5,
.c3 + .c5-c6,
.c3 + .c5 {
margin-left: 25%;
}
Now imagine how the verbosity compounds when we repeat this type of declaration for every possible margin in a grid. The more columns added to the grid, the longer this selector list would get, too, making the CSS harder for the developer to maintain and slowing the load time. Using class-attribute selectors, though, this can be much simpler:
[class*=c3] + [class*=c5] {
margin-left: 25%;
}
I’ve detailed how we extract as much logic as possible from as little CSS as needed on the Gridset blog.
More flexible selectors
In a recent project, I was working with Drupal-generated classes to change styles for certain special pages on a site. Without being able to change the code base, I was left trying to find some specific aspect of the generated HTML to target. I noticed that every special page was given a prefixed class, unique to the page, resulting in CSS like this:
.specialpage-about,
.specialpage-contact,
.specialpage-info,
…
…and the list kept growing with each new special page. Such bloat would lead to problems down the line, and add development overhead to editorial decisions, which was a situation we were trying to avoid. I was easily able to fix this, though, with a concise class-attribute selector:
[class*=specialpage-]
The CSS was now flexible enough to accommodate both the editorial needs of the client, and the development restrictions of the CMS.
Selector performance
As Snook tells us in his chapter on Selector Performance, selectors are read by the browser from right to left, matching every element that adheres to each rule (or part of the selector). The more specific we can make the right-most rules – and every other part of your selectors – the more performant your CSS will be. So this selector:
.home-page .promo .main-header
…would be more performant than:
.home-page div header
…because there are likely many more header and div elements on the page, but not so many elements with those specific classes.
Now, the class-attribute selector could be more general than a class selector, but not by much. I ran numerous tests based on the work of Steve Souders (and a few others) to test a class-attribute selector against a normal class selector. Given that Javascript will freeze during style rendering, I created a script that will add, then remove, a stylesheet on a page 5000 times, and measure only the time that elapses during the rendering freeze. The script runs four tests, essentially: one where a class selector and class-attribute Selector match a single element, and one they match multiple elements on the page.
After running the test over 100 times and averaging the results, I have not seen a significant difference in rendering times. (As of this writing, the class-attribute selector has been 0.398% slower on average.) View the results here.
Given the sheer amount of bytes potentially saved by reducing selector lists, though, I am confident class-attribute selectors could shorten load times on larger sites and, at the very least, save precious development time.
Conclusion
With its flexibility and broad remit, class has at times been derided as too lenient, allowing CMSes and lazy developers to fill its values with presentational hacks or verbose gibberish. There have even been calls for an early retirement. Class continues, though, to be one of our most crucial tools.
Front-end developers are rightfully eager to expand production abilities through innovations such as Sass or LESS, but this should not preclude us from honing the tools we already know as well. Every technique demonstrated in this article was achievable over a decade ago and most of the same thinking could be applied to IDs, rels, or any other attribute (though the reasons listed above give class an edge). The recent advent of methods such as object-oriented CSS and SMACSS shows there is still much room left to expand what simple HTML and CSS can accomplish. Progress may not always be found in the innovation of our tools, but through sharpening our understanding of them. |
2012 |
Nathan Ford |
nathanford |
2012-12-15T00:00:00+00:00 |
https://24ways.org/2012/a-harder-working-class/ |
code |
| 135 |
A Scripting Carol |
We all know the stories of the Ghost of Scripting Past – a time when the web was young and littered with nefarious scripting, designed to bestow ultimate control upon the developer, to pollute markup with event handler after event handler, and to entrench advertising in the minds of all that gazed upon her.
And so it came to be that JavaScript became a dirty word, thrown out of solutions by many a Scrooge without regard to the enhancements that JavaScript could bring to any web page. JavaScript, as it was, was dead as a door-nail.
With the arrival of our core philosophy that all standardistas hold to be true: “separate your concerns – content, presentation and behaviour,” we are in a new era of responsible development the Web Standards Way™. Or are we? Have we learned from the Ghosts of Scripting Past? Or are we now faced with new problems that come with new ways of implementing our solutions?
The Ghost of Scripting Past
If the Ghost of Scripting Past were with us it would probably say:
You must remember your roots and where you came from, and realize the misguided nature of your early attempts for control. That person you see down there, is real and they are the reason you exist in the first place… without them, you are nothing.
In many ways we’ve moved beyond the era of control and we do take into account the user, or at least much more so than we used to. Sadly – there is one advantage that old school inline event handlers had where we assigned and reassigned CSS style property values on the fly – we knew that if JavaScript wasn’t supported, the styles wouldn’t be added because we ended up doing them at the same time.
If anything, we need to have learned from the past that just because it works for us doesn’t mean it is going to work for anyone else – we need to test more scenarios than ever to observe the multitude of browsing arrangements we’ll observe: CSS on with JavaScript off, CSS off/overridden with JavaScript on, both on, both off/not supported. It is a situation that is ripe for conflict.
This may shock some of you, but there was a time when testing was actually easier: back in the day when Netscape 4 was king. Yes, that’s right. I actually kind of enjoyed Netscape 4 (hear me out, please). With NS4’s CSS implementation known as JavaScript Style Sheets, you knew that if JavaScript was off the styles were off too.
The Ghost of Scripting Present
With current best practice – we keep our CSS and JavaScript separate from each other. So what happens when some of our fancy, unobtrusive DOM Scripting doesn’t play nicely with our wonderfully defined style rules?
Lets look at one example of a collapsing and expanding menu to illustrate where we are now:
Simple Collapsing/Expanding Menu Example
We’re using some simple JavaScript (I’m using jquery in this case) to toggle between a CSS state for expanded and not expanded:
JavaScript
$(document).ready(function(){
TWOFOURWAYS.enableTree();
});
var TWOFOURWAYS = new Object();
TWOFOURWAYS.enableTree = function ()
{
$("ul li a").toggle(function(){
$(this.parentNode).addClass("expanded");
}, function() {
$(this.parentNode).removeClass("expanded");
});
return false;
}
CSS
ul li ul {
display: none;
}
ul li.expanded ul {
display: block;
}
At this point we’ve separated our presentation from our content and behaviour, and all is well, right?
Not quite.
Here’s where I typically see failures in the assessment work that I do on web sites and applications (Yes, call me Scrooge – I don’t care!). We know our page needs to work with or without scripting, and we know it needs to work with or without CSS. All too often the testing scenarios don’t take into account combinations.
Testing it out
So what happens when we test this? Make sure you test with:
CSS off
JavaScript off
Use the simple example again.
With CSS off, we revert to a simple nested list of links and all functionality is maintained. With JavaScript off, however, we run into a problem – we have now removed the ability to expand the menu using the JavaScript triggered CSS change.
Hopefully you see the problem – we have a JavaScript and CSS dependency that is critical to the functionality of the page. Unobtrusive scripting and binary on/off tests aren’t enough. We need more.
This Ghost of Scripting Present sighting is seen all too often.
Lets examine the JavaScript off scenario a bit further – if we require JavaScript to expand/show the branch of the tree we should use JavaScript to hide them in the first place. That way we guarantee functionality in all scenarios, and have achieved our baseline level of interoperability.
To revise this then, we’ll start with the sub items expanded, use JavaScript to collapse them, and then use the same JavaScript to expand them.
HTML
<ul>
<li><a href="#">Main Item</a>
<ul class="collapseme">
<li><a href="#">Sub item 1</a></li>
<li><a href="#">Sub item 2</a></li>
<li><a href="#">Sub item 3</a></li>
</ul>
</li>
</ul>
CSS
/* initial style is expanded */
ul li ul.collapseme {
display: block;
}
JavaScript
// remove the class collapseme after the page loads
$("ul ul.collapseme").removeClass("collapseme");
And there you have it – a revised example with better interoperability.
This isn’t rocket surgery by any means. It is a simple solution to a ghostly problem that is too easily overlooked (and often is).
The Ghost of Scripting Future
Well, I’m not so sure about this one, but I’m guessing that in a few years’ time, we’ll all have seen a few more apparitions and have a few more tales to tell. And hopefully we’ll be able to share them on 24 ways.
Thanks to Drew for the invitation to contribute and thanks to everyone else out there for making this a great (and haunting) year on the web! |
2006 |
Derek Featherstone |
derekfeatherstone |
2006-12-21T00:00:00+00:00 |
https://24ways.org/2006/a-scripting-carol/ |
code |
| 98 |
Absolute Columns |
CSS layouts have come quite a long way since the dark ages of web publishing, with all sorts of creative applications of floats, negative margins, and even background images employed in order to give us that most basic building block, the column. As the title implies, we are indeed going to be discussing columns today—more to the point, a handy little application of absolute positioning that may be exactly what you’ve been looking for…
Care for a nightcap?
If you’ve been developing for the web for long enough, you may be familiar with this little children’s fable, passed down from wizened Shaolin monks sitting atop the great Mt. Geocities: “Once upon a time, multiple columns of the same height could be easily created using TABLES.” Now, though we’re all comfortably seated on the standards train (and let’s be honest: even if you like to think you’ve fallen off, if you’ve given up using tables for layout, rest assured your sleeper car is still reserved), this particular—and as page layout goes, quite basic—trick is still a thorn in our CSSides compared to the ease of achieving the same effect using said Tables of Evil™.
See, the orange juice masks the flavor…
Creative solutions such as Dan Cederholm’s Faux Columns do a good job of making it appear as though adjacent columns maintain equal height as content expands, using a background image to fill the space that the columns cannot.
Now, the Holy Grail of CSS columns behaving exactly how they would as table cells—or more to the point, as columns—still eludes us (cough CSS3 Multi-column layout module cough), but sometimes you just need, for example, a secondary column (say, a sidebar) to match the height of a primary column, without involving the creation of images. This is where a little absolute positioning can save you time, while possibly giving your layout a little more flexibility.
Shaken, not stirred
You’re probably familiar by now with the concept of Making the Absolute, Relative as set forth long ago by Doug Bowman, but let’s quickly review just in case: an element set to position:absolute will position itself relative to its nearest ancestor set to position:relative, rather than the browser window (see Figure 1).
Figure 1.
However, what you may not know is that we can anchor more than two sides of an absolutely positioned element. Yes, that’s right, all four sides (top, right, bottom, left) can be set, though in this example we’re only going to require the services of three sides (see Figure 2 for the end result).
Figure 2.
Trust me, this will make you feel better
Our requirements are essentially the same as the standard “absolute-relative” trick—a container <div> set to position:relative, and our sidebar <div> set to position:absolute — plus another <div> that will serve as our main content column. We’ll also add a few other common layout elements (wrapper, header, and footer) so our example markup looks more like a real layout and less like a test case:
<div id="wrapper">
<div id="header">
<h2>#header</h2>
</div>
<div id="container">
<div id="column-left">
<h2>#left</h2>
<p>Lorem ipsum dolor sit amet…</p>
</div>
<div id="column-right">
<h2>#right</h2>
</div>
</div>
<div id="footer">
<h2>#footer</h2>
</div>
</div>
In this example, our main column (#column-left) is only being given a width to fit within the context of the layout, and is otherwise untouched (though we’re using pixels here, this trick will of course work with fluid layouts as well), and our right keeping our styles nice and minimal:
#container {
position: relative;
}
#column-left {
width: 480px;
}
#column-right {
position: absolute;
top: 10px;
right: 10px;
bottom: 10px;
width: 250px;
}
The trick is a simple one: the #container <div> will expand vertically to fit the content within #column-left. By telling our sidebar <div> (#column-right) to attach itself not only to the top and right edges of #container, but also to the bottom, it too will expand and contract to match the height of the left column (duplicate the “lorem ipsum” paragraph a few times to see it in action).
Figure 3.
On the rocks
“But wait!” I hear you exclaim, “when the right column has more content than the left column, it doesn’t expand! My text runneth over!” Sure enough, that’s exactly what happens, and what’s more, it’s supposed to: Absolutely positioned elements do exactly what you tell them to do, and unfortunately aren’t very good at thinking outside the box (get it? sigh…).
However, this needn’t get your spirits down, because there’s an easy way to address the issue: by adding overflow:auto to #column-right, a scrollbar will automatically appear if and when needed:
#column-right {
position: absolute;
top: 10px;
right: 10px;
bottom: 10px;
width: 250px;
overflow: auto;
}
While this may limit the trick’s usefulness to situations where the primary column will almost always have more content than the secondary column—or where the secondary column’s content can scroll with wild abandon—a little prior planning will make it easy to incorporate into your designs.
Driving us to drink
It just wouldn’t be right to have a friendly, festive holiday tutorial without inviting IE6, though in this particular instance there will be no shaming that old browser into admitting it has a problem, nor an intervention and subsequent 12-step program. That’s right my friends, this tutorial has abstained from IE6-abuse now for 30 days, thanks to the wizard Dean Edwards and his amazingly talented IE7 Javascript library.
Simply drop the Conditional Comment and <script> element into the <head> of your document, along with one tiny CSS hack that only IE6 (and below) will ever see, and that browser will be back on the straight and narrow:
<!--[if lt IE 7]>
<script src="http://ie7-js.googlecode.com/svn/version/2.0(beta3)/IE7.js" type="text/javascript"></script>
<style type="text/css" media="screen">
#container {
zoom:1; /* helps fix IE6 by initiating hasLayout */
}
</style>
<![endif]-->
Eggnog is supposed to be spiked, right?
Of course, this is one simple example of what can be a much more powerful technique, depending on your needs and creativity. Just don’t go coding up your wildest fantasies until you’ve had a chance to sleep off the Christmas turkey and whatever tasty liquids you happen to imbibe along the way… |
2008 |
Dan Rubin |
danrubin |
2008-12-22T00:00:00+00:00 |
https://24ways.org/2008/absolute-columns/ |
code |
| 213 |
Accessibility Through Semantic HTML |
Working on Better, a tracker blocker, I spend an awful lot of my time with my nose in other people’s page sources. I’m mostly there looking for harmful tracking scripts, but often notice the HTML on some of the world’s most popular sites is in a sad state of neglect.
What does neglected HTML look like? Here’s an example of the markup I found on a news site just yesterday. There’s a bit of text, a few links, and a few images. But mostly it’s div elements.
<div class="block_wrapper">
<div class="block_content">
<div class="box">
<div id="block1242235">
<div class="column">
<div class="column_content">
<a class="close" href="#"><i class="fa"></i></a>
</div>
<div class="btn account_login"></div>
Some text <span>more text</span>
</div>
</div>
</div>
</div>
</div>
divs and spans, why do we use them so much?
While I find tracking scripts completely inexcusable, I do understand why people write HTML like the above. As developers, we like to use divs and spans as they’re generic elements. They come with no associated default browser styles or behaviour except that div displays as a block, and span displays inline. If we make our page up out of divs and spans, we know we’ll have absolute control over styles and behaviour cross-browser, and we won’t need a CSS reset.
Absolute control may seem like an advantage, but there’s a greater benefit to less generic, more semantic elements. Browsers render semantic elements with their own distinct styles and behaviours. For example, button looks and behaves differently from a. And ul is different from ol. These defaults are shortcuts to a more usable and accessible web. They provide consistent and well-tested components for common interactions.
Semantic elements aid usability
A good example of how browser defaults can benefit the usability of an element is in the <select> option menu. In Safari on the desktop, the browser renders <select> as a popover-style menu. On a touchscreen, Safari overlays the same menu over the lower half of the screen as a “picker view.”
Option menu in Safari on macOS.
Option menu picker in Safari on iOS.
The iOS picker is a much better experience than struggling to pick from a complicated interface inside the page. The menu is shown more clearly than in the confined space on the page, which makes the options easier to read. The required swipe and tap gestures are consistent with the rest of the operating system, making the expected interaction easier to understand. The whole menu is scaled up, meaning the gestures don’t need such fine motor control. Good usability is good accessibility.
When we choose to use a div or span over a more semantic HTML element, we’re also doing hard work the browser could be doing for us. We don’t need to tie ourselves in knots making a custom div into a keyboard navigable option menu. Using select passes the bulk of the responsibility over to the browser.
Letting the browser do most of the work is also more future-friendly. More devices, with different expected interactions, will be released in the future. When that happens, the devices’ browsers can adapt our sites according to those interactions. Then we can spend our time doing something more fun than rewriting cross-browser JavaScript for each new device.
HTML’s impact on accessibility
Assistive technology also uses semantic HTML to understand how best to convey each element to its user.
For screen readers
Semantic HTML gives context to screen readers. Screen readers are a type of assistive technology that reads the content of the screen to the person using it. All sites have a linear page source. Sighted visitors can use visual cues on the page to navigate to their desired content in a non-linear fashion. As screen readers output audio (and sometimes braille), those visual cues aren’t usable in the same way.
Screen readers provide alternative means of navigation, enabling people to jump between different types of content, such as links, forms, headings, lists, and paragraphs. If all our content is marked up using divs and spans, we’re not giving screen readers a chance to index the valuable content.
For keyboard navigation
Keyboard-only navigation is also aided by semantic HTML. Forms, option menus, navigation, video, and audio are particularly hard for people relying on a keyboard to access. For instance, option menus and navigation can be very fiddly if you need to use a mouse to hover a menu open and move to select the desired item at the same time.
Again, we can leave much of the interaction to the browser through semantic HTML. Semantic form elements can convey if a check box has been checked, or which label is associated with which input field. These default behaviours can make the difference between a person being able to use a form or leaving the site out of frustration.
Did I convince you yet? I hope so. Let’s finish with some easy guidelines to follow.
1. Use the most semantic HTML element for the job
When you reach for a div, first check if there’s a better element to do the job. What is the role of that element? How should a person be interacting with the element?
Are you using class names like nav, header, or main? There are HTML5 elements for those sections! Using specific elements can also make writing CSS simpler, and ensure a consistent design with minimal effort.
2. Separate structure and style
Don’t choose HTML elements based on how they’re styled in your CSS. Nowadays, common practice is to use class names rather than elements for CSS selectors. You’re unlikely to wrap all your page content in an <h1> element because you want all the text to be big and bold. Still, it can be easy to choose an HTML element because it will be the easiest to style. Focusing on content without style will help us choose the most semantic HTML element without that temptation. For example, you could add a class of .btn to a div to make it look like a button. But we all know that only a button will really behave like a button.
3. Use progressive enhancement for enhanced functionality
Airbnb and Groupon recently proved we’re not past the laziness of “this site only works in X browser.” Baffling disregard for the open web aside, making complex interactive experiences work cross-browser and cross-device is not easy. We can use progressive enhancement to layer fancy or unsupported features on top of a baseline “it works” experience.
We should build the baseline experience on a foundation of accessible, semantic HTML. Then, if you really want to add a specific feature for a proprietary browser, you can layer that on top, without breaking the underlying experience.
4. Test your work
Validators are always valuable for checking the browser will be able to correctly interpret your markup. Document outline checkers can be valuable for testing your structure, but be aware that the HTML5 document outline is not actually implemented in browsers.
Once you’ve got something resembling a web page, test the experience! Ensure that semantic HTML element you chose looks and behaves in a predictable manner consistent with its use across the web. Test cross-browser, test cross-device, and test with assistive technology. Testing with assistive technology is not as expensive as it used to be, you can even use your smartphone for testing on iOS and Android. Your visitors will thank you!
Further reading
Accessibility For Everyone by Laura Kalbag
HTML5 Doctor
HTML5 Accessibility
An overview of HTML5 Semantics
HTML reference on MDN
Heydon Pickering’s Inclusive Design Checklist
The Paciello Group’s Inclusive Design Principles |
2017 |
Laura Kalbag |
laurakalbag |
2017-12-15T00:00:00+00:00 |
https://24ways.org/2017/accessibility-through-semantic-html/ |
code |
| 234 |
An Introduction to CSS 3-D Transforms |
Ladies and gentlemen, it is the second decade of the third millennium and we are still kicking around the same 2-D interface we got three decades ago. Sure, Apple debuted a few apps for OSX 10.7 that have a couple more 3-D flourishes, and Microsoft has had that Flip 3D for a while. But c’mon – 2011 is right around the corner. That’s Twenty Eleven, folks. Where is our 3-D virtual reality? By now, we should be zipping around the Metaverse on super-sonic motorbikes.
Granted, the capability of rendering complex 3-D environments has been present for years. On the web, there are already several solutions: Flash; three.js in <canvas>; and, eventually, WebGL. Finally, we meagre front-end developers have our own three-dimensional jewel: CSS 3-D transforms!
Rationale
Like a beautiful jewel, 3-D transforms can be dazzling, a true spectacle to behold. But before we start tacking 3-D diamonds and rubies to our compositions like Liberace‘s tailor, we owe it to our users to ask how they can benefit from this awesome feature.
An entire application should not take advantage of 3-D transforms. CSS was built to style documents, not generate explorable environments. I fail to find a benefit to completing a web form that can be accessed by swivelling my viewport to the Sign-Up Room (although there have been proposals to make the web just that). Nevertheless, there are plenty of opportunities to use 3-D transforms in between interactions with the interface, via transitions.
Take, for instance, the Weather App on the iPhone. The application uses two views: a details view; and an options view. Switching between these two views is done with a 3-D flip transition. This informs the user that the interface has two – and only two – views, as they can exist only on either side of the same plane.
Flipping from details view to options view via a 3-D transition
Also, consider slide shows. When you’re looking at the last slide, what cues tip you off that advancing will restart the cycle at the first slide? A better paradigm might be achieved with a 3-D transform, placing the slides side-by-side in a circle (carousel) in three-dimensional space; in that arrangement, the last slide obviously comes before the first.
3-D transforms are more than just eye candy. We can also use them to solve dilemmas and make our applications more intuitive.
Current support
The CSS 3D Transforms module has been out in the wild for over a year now. Currently, only Safari supports the specification – which includes Safari on Mac OS X and Mobile Safari on iOS.
The support roadmap for other browsers varies. The Mozilla team has taken some initial steps towards implementing the module. Mike Taylor tells me that the Opera team is keeping a close eye on CSS transforms, and is waiting until the specification is fleshed out. And our best friend Internet Explorer still needs to catch up to 2-D transforms before we can talk about the 3-D variety.
To make matters more perplexing, Safari’s WebKit cousin Chrome currently accepts 3-D transform declarations, but renders them in 2-D space. Chrome team member Paul Irish, says that 3-D transforms are on the horizon, perhaps in one of the next 8.0 releases.
This all adds up to a bit of a challenge for those of us excited by 3-D transforms. I’ll give it to you straight: missing the dimension of depth can make degradation a bit ungraceful. Unless the transform is relatively simple and holds up in non-3D-supporting browsers, you’ll most likely have to design another solution. But what’s another hurdle in a steeplechase? We web folk have had our mettle tested for years. We’re prepared to devise multiple solutions.
Here’s the part of the article where I mention Modernizr, and you brush over it because you’ve read this part of an article hundreds of times before. But seriously, it’s the best way to test for CSS 3-D transform support. Use it.
Even with these difficulties mounting up, trying out 3-D transforms today is the right move. The CSS 3-D transforms module was developed by the same team at Apple that produced the CSS 2D Transforms and Animation modules. Both specifications have since been adopted by Mozilla and Opera. Transforming in three-dimensions now will guarantee you’ll be ahead of the game when the other browsers catch up.
The choice is yours. You can make excuses and pooh-pooh 3-D transforms because they’re too hard and only snobby Apple fans will see them today. Or, with a tip of the fedora to Mr Andy Clarke, you can get hard-boiled and start designing with the best features out there right this instant.
So, I bid you, in the words of the eternal Optimus Prime…
Transform and roll out.
Let’s get coding.
Perspective
To activate 3-D space, an element needs perspective. This can be applied in two ways: using the transform property, with the perspective as a functional notation:
-webkit-transform: perspective(600);
or using the perspective property:
-webkit-perspective: 600;
See example: Perspective 1.
The red element on the left uses transform: perspective() functional notation; the blue element on the right uses the perspective property
These two formats both trigger a 3-D space, but there is a difference. The first, functional notation is convenient for directly applying a 3-D transform on a single element (in the previous example, I use it in conjunction with a rotateY transform). But when used on multiple elements, the transformed elements don’t line up as expected. If you use the same transform across elements with different positions, each element will have its own vanishing point. To remedy this, use the perspective property on a parent element, so each child shares the same 3-D space.
See Example: Perspective 2.
Each red box on the left has its own vanishing point within the parent container; the blue boxes on the right share the vanishing point of the parent container
The value of perspective determines the intensity of the 3-D effect. Think of it as a distance from the viewer to the object. The greater the value, the further the distance, so the less intense the visual effect. perspective: 2000; yields a subtle 3-D effect, as if we were viewing an object from far away. perspective: 100; produces a tremendous 3-D effect, like a tiny insect viewing a massive object.
By default, the vanishing point for a 3-D space is positioned at its centre. You can change the position of the vanishing point with perspective-origin property.
-webkit-perspective-origin: 25% 75%;
See Example: Perspective 3.
3-D transform functions
As a web designer, you’re probably well acquainted with working in two dimensions, X and Y, positioning items horizontally and vertically. With a 3-D space initialised with perspective, we can now transform elements in all three glorious spatial dimensions, including the third Z dimension, depth.
3-D transforms use the same transform property used for 2-D transforms. If you’re familiar with 2-D transforms, you’ll find the basic 3D transform functions fairly similar.
rotateX(angle)
rotateY(angle)
rotateZ(angle)
translateZ(tz)
scaleZ(sz)
Whereas translateX() positions an element along the horizontal X-axis, translateZ() positions it along the Z-axis, which runs front to back in 3-D space. Positive values position the element closer to the viewer, negative values further away.
The rotate functions rotate the element around the corresponding axis. This is somewhat counter-intuitive at first, as you might imagine that rotateX will spin an object left to right. Instead, using rotateX(45deg) rotates an element around the horizontal X-axis, so the top of the element angles back and away, and the bottom gets closer to the viewer.
See Example: Transforms 1.
3-D rotate() and translate() functions around each axis
There are also several shorthand transform functions that require values for all three dimensions:
translate3d(tx,ty,tz)
scale3d(sx,sy,sz)
rotate3d(rx,ry,rz,angle)
Pro-tip: These foo3d() transform functions also have the benefit of triggering hardware acceleration in Safari. Dean Jackson, CSS 3-D transform spec author and main WebKit dude, writes (to Thomas Fuchs):
In essence, any transform that has a 3D operation as one of its functions will trigger hardware compositing, even when the actual transform is 2D, or not doing anything at all (such as translate3d(0,0,0)). Note this is just current behaviour, and could change in the future (which is why we don’t document or encourage it). But it is very helpful in some situations and can significantly improve redraw performance.
For the sake of simplicity, my demos will use the basic transform functions, but if you’re writing production-ready CSS for iOS or Safari-only, make sure to use the foo3d() functions to get the best rendering performance.
Card flip
We now have all the tools to start making 3-D objects. Let’s get started with something simple: flipping a card.
Here’s the basic markup we’ll need:
<section class="container">
<div id="card">
<figure class="front">1</figure>
<figure class="back">2</figure>
</div>
</section>
The .container will house the 3-D space. The #card acts as a wrapper for the 3-D object. Each face of the card has a separate element: .front; and .back. Even for such a simple object, I recommend using this same pattern for any 3-D transform. Keeping the 3-D space element and the object element(s) separate establishes a pattern that is simple to understand and easier to style.
We’re ready for some 3-D stylin’. First, apply the necessary perspective to the parent 3-D space, along with any size or positioning styles.
.container {
width: 200px;
height: 260px;
position: relative;
-webkit-perspective: 800;
}
Now the #card element can be transformed in its parent’s 3-D space. We’re combining absolute and relative positioning so the 3-D object is removed from the flow of the document. We’ll also add width: 100%; and height: 100%;. This ensures the object’s transform-origin will occur in the centre of .container. More on transform-origin later.
Let’s add a CSS3 transition so users can see the transform take effect.
#card {
width: 100%;
height: 100%;
position: absolute;
-webkit-transform-style: preserve-3d;
-webkit-transition: -webkit-transform 1s;
}
The .container’s perspective only applies to direct descendant children, in this case #card. In order for subsequent children to inherit a parent’s perspective, and live in the same 3-D space, the parent can pass along its perspective with transform-style: preserve-3d. Without 3-D transform-style, the faces of the card would be flattened with its parents and the back face’s rotation would be nullified.
To position the faces in 3-D space, we’ll need to reset their positions in 2-D with position: absolute. In order to hide the reverse sides of the faces when they are faced away from the viewer, we use backface-visibility: hidden.
#card figure {
display: block;
position: absolute;
width: 100%;
height: 100%;
-webkit-backface-visibility: hidden;
}
To flip the .back face, we add a basic 3-D transform of rotateY(180deg).
#card .front {
background: red;
}
#card .back {
background: blue;
-webkit-transform: rotateY(180deg);
}
With the faces in place, the #card requires a corresponding style for when it is flipped.
#card.flipped {
-webkit-transform: rotateY(180deg);
}
Now we have a working 3-D object. To flip the card, we can toggle the flipped class. When .flipped, the #card will rotate 180 degrees, thus exposing the .back face.
See Example: Card 1.
Flipping a card in three dimensions
Slide-flip
Take another look at the Weather App 3-D transition. You’ll notice that it’s not quite the same effect as our previous demo. If you follow the right edge of the card, you’ll find that its corners stay within the container. Instead of pivoting from the horizontal centre, it pivots on that right edge. But the transition is not just a rotation – the edge moves horizontally from right to left. We can reproduce this transition just by modifying a couple of lines of CSS from our original card flip demo.
The pivot point for the rotation occurs at the right side of the card. By default, the transform-origin of an element is at its horizontal and vertical centre (50% 50% or center center). Let’s change it to the right side:
#card { -webkit-transform-origin: right center; }
That flip now needs some horizontal movement with translateX. We’ll set the rotation to -180deg so it flips right side out.
#card.flipped {
-webkit-transform: translateX(-100%) rotateY(-180deg);
}
See Example: Card 2.
Creating a slide-flip from the right edge of the card
Cube
Creating 3-D card objects is a good way to get started with 3-D transforms. But once you’ve mastered them, you’ll be hungry to push it further and create some true 3-D objects: prisms. We’ll start out by making a cube.
The markup for the cube is similar to the card. This time, however, we need six child elements for all six faces of the cube:
<section class="container">
<div id="cube">
<figure class="front">1</figure>
<figure class="back">2</figure>
<figure class="right">3</figure>
<figure class="left">4</figure>
<figure class="top">5</figure>
<figure class="bottom">6</figure>
</div>
</section>
Basic position and size styles set the six faces on top of one another in the container.
.container {
width: 200px;
height: 200px;
position: relative;
-webkit-perspective: 1000;
}
#cube {
width: 100%;
height: 100%;
position: absolute;
-webkit-transform-style: preserve-3d;
}
#cube figure {
width: 196px;
height: 196px;
display: block;
position: absolute;
border: 2px solid black;
}
With the card, we only had to rotate its back face. The cube, however, requires that five of the six faces to be rotated. Faces 1 and 2 will be the front and back. Faces 3 and 4 will be the sides. Faces 5 and 6 will be the top and bottom.
#cube .front { -webkit-transform: rotateY(0deg); }
#cube .back { -webkit-transform: rotateX(180deg); }
#cube .right { -webkit-transform: rotateY(90deg); }
#cube .left { -webkit-transform: rotateY(-90deg); }
#cube .top { -webkit-transform: rotateX(90deg); }
#cube .bottom { -webkit-transform: rotateX(-90deg); }
We could remove the first #cube .front style declaration, as this transform has no effect, but let’s leave it in to keep our code consistent.
Now each face is rotated, and only the front face is visible. The four side faces are all perpendicular to the viewer, so they appear invisible. To push them out to their appropriate sides, they need to be translated out from the centre of their positions. Each side of the cube is 200 pixels wide. From the cube’s centre they’ll need to be translated out half that distance, 100px.
#cube .front { -webkit-transform: rotateY(0deg) translateZ(100px); }
#cube .back { -webkit-transform: rotateX(180deg) translateZ(100px); }
#cube .right { -webkit-transform: rotateY(90deg) translateZ(100px); }
#cube .left { -webkit-transform: rotateY(-90deg) translateZ(100px); }
#cube .top { -webkit-transform: rotateX(90deg) translateZ(100px); }
#cube .bottom { -webkit-transform: rotateX(-90deg) translateZ(100px); }
Note here that the translateZ function comes after the rotate. The order of transform functions is important. Take a moment and soak this up. Each face is first rotated towards its position, then translated outward in a separate vector.
We have a working cube, but we’re not done yet.
Returning to the Z-axis origin
For the sake of our users, our 3-D transforms should not distort the interface when the active panel is at its resting position. But once we start pushing elements off their Z-axis origin, distortion is inevitable.
In order to keep 3-D transforms snappy, Safari composites the element, then applies the transform. Consequently, anti-aliasing on text will remain whatever it was before the transform was applied. When transformed forward in 3-D space, significant pixelation can occur.
See Example: Transforms 2.
Looking back at the Perspective 3 demo, note that no matter how small the perspective value is, or wherever the transform-origin may be, the panel number 1 always returns to its original position, as if all those funky 3-D transforms didn’t even matter.
To resolve the distortion and restore pixel perfection to our #cube, we can push the 3-D object back, so that the front face will be positioned back to the Z-axis origin.
#cube { -webkit-transform: translateZ(-100px); }
See Example: Cube 1.
Restoring the front face to the original position on the Z-axis
Rotating the cube
To expose any face of the cube, we’ll need a style that rotates the cube to expose any face. The transform values are the opposite of those for the corresponding face. We toggle the necessary class on the #box to apply the appropriate transform.
#cube.show-front { -webkit-transform: translateZ(-100px) rotateY(0deg); }
#cube.show-back { -webkit-transform: translateZ(-100px) rotateX(-180deg); }
#cube.show-right { -webkit-transform: translateZ(-100px) rotateY(-90deg); }
#cube.show-left { -webkit-transform: translateZ(-100px) rotateY(90deg); }
#cube.show-top { -webkit-transform: translateZ(-100px) rotateX(-90deg); }
#cube.show-bottom { -webkit-transform: translateZ(-100px) rotateX(90deg); }
Notice how the order of the transform functions has reversed. First, we push the object back with translateZ, then we rotate it.
Finishing up, we can add a transition to animate the rotation between states.
#cube { -webkit-transition: -webkit-transform 1s; }
See Example: Cube 2.
Rotating the cube with a CSS transition
Rectangular prism
Cubes are easy enough to generate, as we only have to worry about one measurement. But how would we handle a non-regular rectangular prism? Let’s try to make one that’s 300 pixels wide, 200 pixels high, and 100 pixels deep.
The markup remains the same as the #cube, but we’ll switch the cube id for #box. The container styles remain mostly the same:
.container {
width: 300px;
height: 200px;
position: relative;
-webkit-perspective: 1000;
}
#box {
width: 100%;
height: 100%;
position: absolute;
-webkit-transform-style: preserve-3d;
}
Now to position the faces. Each set of faces will need their own sizes. The smaller faces (left, right, top and bottom) need to be positioned in the centre of the container, where they can be easily rotated and then shifted outward. The thinner left and right faces get positioned left: 100px ((300 − 100) ÷ 2), The stouter top and bottom faces get positioned top: 50px ((200 − 100) ÷ 2).
#box figure {
display: block;
position: absolute;
border: 2px solid black;
}
#box .front,
#box .back {
width: 296px;
height: 196px;
}
#box .right,
#box .left {
width: 96px;
height: 196px;
left: 100px;
}
#box .top,
#box .bottom {
width: 296px;
height: 96px;
top: 50px;
}
The rotate values can all remain the same as the cube example, but for this rectangular prism, the translate values do differ. The front and back faces are each shifted out 50 pixels since the #box is 100 pixels deep. The translate value for the left and right faces is 150 pixels for their 300 pixels width. Top and bottom panels take 100 pixels for their 200 pixels height:
#box .front { -webkit-transform: rotateY(0deg) translateZ(50px); }
#box .back { -webkit-transform: rotateX(180deg) translateZ(50px); }
#box .right { -webkit-transform: rotateY(90deg) translateZ(150px); }
#box .left { -webkit-transform: rotateY(-90deg) translateZ(150px); }
#box .top { -webkit-transform: rotateX(90deg) translateZ(100px); }
#box .bottom { -webkit-transform: rotateX(-90deg) translateZ(100px); }
See Example: Box 1.
Just like the cube example, to expose a face, the #box needs to have a style to reverse that face’s transform. Both the translateZ and rotate values are the opposites of the corresponding face.
#box.show-front { -webkit-transform: translateZ(-50px) rotateY(0deg); }
#box.show-back { -webkit-transform: translateZ(-50px) rotateX(-180deg); }
#box.show-right { -webkit-transform: translateZ(-150px) rotateY(-90deg); }
#box.show-left { -webkit-transform: translateZ(-150px) rotateY(90deg); }
#box.show-top { -webkit-transform: translateZ(-100px) rotateX(-90deg); }
#box.show-bottom { -webkit-transform: translateZ(-100px) rotateX(90deg); }
See Example: Box 2.
Rotating the rectangular box with a CSS transition
Carousel
Front-end developers have a myriad of choices when it comes to content carousels. Now that we have 3-D capabilities in our browsers, why not take a shot at creating an actual 3-D carousel?
The markup for this demo takes the same form as the box, cube and card. Let’s make it interesting and have a carousel with nine panels.
<div class="container">
<div id="carousel">
<figure>1</figure>
<figure>2</figure>
<figure>3</figure>
<figure>4</figure>
<figure>5</figure>
<figure>6</figure>
<figure>7</figure>
<figure>8</figure>
<figure>9</figure>
</div>
</div>
Now, apply basic layout styles. Let’s give each panel of the #carousel 20 pixel gaps between one another, done here with left: 10px; and top: 10px;. The effective width of each panel is 210 pixels.
.container {
width: 210px;
height: 140px;
position: relative;
-webkit-perspective: 1000;
}
#carousel {
width: 100%;
height: 100%;
position: absolute;
-webkit-transform-style: preserve-3d;
}
#carousel figure {
display: block;
position: absolute;
width: 186px;
height: 116px;
left: 10px;
top: 10px;
border: 2px solid black;
}
Next up: rotating the faces. This #carousel has nine panels. If each panel gets an equal distribution on the carousel, each panel would be rotated forty degrees from its neighbour (360 ÷ 9).
#carousel figure:nth-child(1) { -webkit-transform: rotateY(0deg); }
#carousel figure:nth-child(2) { -webkit-transform: rotateY(40deg); }
#carousel figure:nth-child(3) { -webkit-transform: rotateY(80deg); }
#carousel figure:nth-child(4) { -webkit-transform: rotateY(120deg); }
#carousel figure:nth-child(5) { -webkit-transform: rotateY(160deg); }
#carousel figure:nth-child(6) { -webkit-transform: rotateY(200deg); }
#carousel figure:nth-child(7) { -webkit-transform: rotateY(240deg); }
#carousel figure:nth-child(8) { -webkit-transform: rotateY(280deg); }
#carousel figure:nth-child(9) { -webkit-transform: rotateY(320deg); }
Now, the outward shift. Back when we were creating the cube and box, the translate value was simple to calculate, as it was equal to one half the width, height or depth of the object. With this carousel, there is no size we can automatically use as a reference. We’ll have to calculate the distance of the shift by other means.
Drawing a diagram of the carousel, we can see that we know only two things: the width of each panel is 210 pixels; and the each panel is rotated forty degrees from the next. If we split one of these segments down its centre, we get a right-angled triangle, perfect for some trigonometry.
We can determine the length of r in this diagram with a basic tangent equation:
There you have it: the panels need to be translated 288 pixels in 3-D space.
#carousel figure:nth-child(1) { -webkit-transform: rotateY(0deg) translateZ(288px); }
#carousel figure:nth-child(2) { -webkit-transform: rotateY(40deg) translateZ(288px); }
#carousel figure:nth-child(3) { -webkit-transform: rotateY(80deg) translateZ(288px); }
#carousel figure:nth-child(4) { -webkit-transform: rotateY(120deg) translateZ(288px); }
#carousel figure:nth-child(5) { -webkit-transform: rotateY(160deg) translateZ(288px); }
#carousel figure:nth-child(6) { -webkit-transform: rotateY(200deg) translateZ(288px); }
#carousel figure:nth-child(7) { -webkit-transform: rotateY(240deg) translateZ(288px); }
#carousel figure:nth-child(8) { -webkit-transform: rotateY(280deg) translateZ(288px); }
#carousel figure:nth-child(9) { -webkit-transform: rotateY(320deg) translateZ(288px); }
If we decide to change the width of the panel or the number of panels, we only need to plug in those two variables into our equation to get the appropriate translateZ value. In JavaScript terms, that equation would be:
var tz = Math.round( ( panelSize / 2 ) /
Math.tan( ( ( Math.PI * 2 ) / numberOfPanels ) / 2 ) );
// or simplified to
var tz = Math.round( ( panelSize / 2 ) /
Math.tan( Math.PI / numberOfPanels ) );
Just like our previous 3-D objects, to show any one panel we need only apply the reverse transform on the carousel. Here’s the style to show the fifth panel:
-webkit-transform: translateZ(-288px) rotateY(-160deg);
See Example: Carousel 1.
By now, you probably have two thoughts:
Rewriting transform styles for each panel looks tedious.
Why bother doing high school maths? Aren’t robots supposed to be doing all this work for us?
And you’re absolutely right. The repetitive nature of 3-D objects lends itself to scripting. We can offload all the monotonous transform styles to our dynamic script, which, if done correctly, will be more flexible than the hard-coded version.
See Example: Carousel 2.
Conclusion
3-D transforms change the way we think about the blank canvas of web design. Better yet, they change the canvas itself, trading in the flat surface for voluminous depth.
My hope is that you took at least one peak at a demo and were intrigued. We web designers, who have rejoiced for border-radius, box-shadow and background gradients, now have an incredible tool at our disposal in 3-D transforms. They deserve just the same enthusiasm, research and experimentation we have seen on other CSS3 features. Now is the perfect time to take the plunge and start thinking about how to use three dimensions to elevate our craft. I’m breathless waiting for what’s to come.
See you on the flip side. |
2010 |
David DeSandro |
daviddesandro |
2010-12-14T00:00:00+00:00 |
https://24ways.org/2010/intro-to-css-3d-transforms/ |
code |
| 42 |
An Overview of SVG Sprite Creation Techniques |
SVG can be used as an icon system to replace icon fonts. The reasons why SVG makes for a superior icon system are numerous, but we won’t be going over them in this article. If you don’t use SVG icons and are interested in knowing why you may want to use them, I recommend you check out “Inline SVG vs Icon Fonts” by Chris Coyier – it covers the most important aspects of both systems and compares them with each other to help you make a better decision about which system to choose.
Once you’ve made the decision to use SVG instead of icon fonts, you’ll need to think of the best way to optimise the delivery of your icons, and ways to make the creation and use of icons faster.
Just like bitmaps, we can create image sprites with SVG – they don’t look or work exactly alike, but the basic concept is pretty much the same.
There are several ways to create SVG sprites, and this article will give you an overview of three of them. While we’re at it, we’re going to take a look at some of the available tools used to automate sprite creation and fallback for us.
Prerequisites
The content of this article assumes you are familiar with SVG. If you’ve never worked with SVG before, you may want to look at some of the introductory tutorials covering SVG syntax, structure and embedding techniques. I recommend the following:
SVG basics: Using SVG.
Structure: Structuring, Grouping, and Referencing in SVG — The <g>, <use>, <defs> and <symbol> Elements. We’ll mention <use> and <symbol> quite a bit in this article.
Embedding techniques: Styling and Animating SVGs with CSS. The article covers several topics, but the section linked focuses on embedding techniques.
A compendium of SVG resources compiled by Chris Coyier — contains resources to almost every aspect of SVG you might be interested in.
And if you’re completely new to the concept of spriting, Chris Coyier’s CSS Sprites explains all about them.
Another important SVG feature is the viewBox attribute. For some of the techniques, knowing your way around this attribute is not required, but it’s definitely more useful if you understand – even if just vaguely – how it works. The last technique mentioned in the article requires that you do know the attribute’s syntax and how to use it. To learn all about viewBox, you can refer to my blog post about SVG coordinate systems.
With the prerequisites in place, let’s move on to spriting SVGs!
Before you sprite…
In order to create an SVG sprite with your icons, you’ll of course need to have these icons ready for use.
Some spriting tools require that you place your icons in a folder to which a certain spriting process is to be applied. As such, for all of the upcoming sections we’ll work on the assumption that our SVG icons are placed in a folder named SVG.
Each icon is an individual .svg file.
You’ll need to make sure each icon is well-prepared and optimised for use – make sure you’ve cleaned up the code by running it through one of the optimisation tools or processes available (or doing it manually if it’s not tedious).
After prepping the icon files and placing them in a folder, we’re ready to create our SVG sprite.
HTML inline SVG sprites
Since SVG is XML code, it can be embedded inline in an HTML document as a code island using the <svg> element. Chris Coyier wrote about this technique first on CSS-Tricks.
The embedded SVG will serve as a container for our icons and is going to be the actual sprite we’re going to use. So we’ll start by including the SVG in our document.
<!DOCTYPE html>
<!-- HTML document stuff -->
<svg style="display:none;">
<!-- icons here -->
</svg>
<!-- other document stuff -->
</html>
Next, we’re going to place the icons inside the <svg>. Each icon will be wrapped in a <symbol> element we can then reference and use elsewhere in the page using the SVG <use> element. The <symbol> element has many benefits, and we’re using it because it allows us to define a symbol (which is a convenient markup for an icon) without rendering that symbol on the screen. The elements defined inside <symbol> will only be rendered when they are referenced – or called – by the <use> element.
Moreover, <symbol> can have its own viewBox attribute, which makes it possible to control the positioning of its content inside its container at any time.
Before we move on, I’d like to shed some light on the style="display:none;" part of the snippet above. Without setting the display of the SVG to none, and even though its contents are not rendered on the page, the SVG will still take up space in the page, resulting in a big empty area. In order to avoid that, we’re hiding the SVG entirely with CSS.
Now, suppose we have a Twitter icon in the icons folder. twitter.svg might look something like this:
<!-- twitter.svg -->
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="32" height="32" viewBox="0 0 32 32">
<path d="M32 6.076c-1.177 0.522-2.443 0.875-3.771 1.034 1.355-0.813 2.396-2.099 2.887-3.632-1.269 0.752-2.674 1.299-4.169 1.593-1.198-1.276-2.904-2.073-4.792-2.073-3.626 0-6.565 2.939-6.565 6.565 0 0.515 0.058 1.016 0.17 1.496-5.456-0.274-10.294-2.888-13.532-6.86-0.565 0.97-0.889 2.097-0.889 3.301 0 2.278 1.159 4.287 2.921 5.465-1.076-0.034-2.088-0.329-2.974-0.821-0.001 0.027-0.001 0.055-0.001 0.083 0 3.181 2.263 5.834 5.266 6.437-0.551 0.15-1.131 0.23-1.73 0.23-0.423 0-0.834-0.041-1.235-0.118 0.835 2.608 3.26 4.506 6.133 4.559-2.247 1.761-5.078 2.81-8.154 2.81-0.53 0-1.052-0.031-1.566-0.092 2.905 1.863 6.356 2.95 10.064 2.95 12.076 0 18.679-10.004 18.679-18.68 0-0.285-0.006-0.568-0.019-0.849 1.283-0.926 2.396-2.082 3.276-3.398z" fill="#000000"></path>
</svg>
We don’t need the root svg element, so we’ll strip the code and only keep the parts that make up the Twitter icon’s shape, which in this example is just the <path> element.Let’s drop that into the sprite container like so:
<svg style="display:none;">
<symbol id="twitter-icon" viewBox="0 0 32 32">
<path d="M32 6.076c-1.177 …" fill="#000000"></path>
</symbol>
<!-- remaining icons here -->
<symbol id="instagram-icon" viewBox="0 0 32 32">
<!-- icon contents -->
</symbol>
<!-- etc. -->
</svg>
Repeat for the other icons.
The value of the <symbol> element’s viewBox attribute depends on the size of the SVG. You don’t need to know how the viewBox works to use it in this case. Its value is made up of four parts: the first two will almost always be “0 0”; the second two will be equal to the size of the icon. For example, our Twitter icon is 32px by 32px (see twitter.svg above), so the viewBox value is “0 0 32 32”.
That said, it is certainly useful to understand how the viewBox works – it can help you troubleshoot SVG sometimes and gives you better control over it, allowing you to scale, position and even crop SVGs manually without having to resort to an editor. My blog post explains all about the viewBox attribute and its related attributes.
Once you have your SVG sprite ready, you can display the icons anywhere on the page by referencing them using the SVG <use> element:
<svg class="twitter-icon">
<use xlink:href="#twitter-icon"></use>
<svg>
And that’s all there is to it!
HTML-inline SVG sprites are simple to create and use, but when you have a lot of icons (and the more icon sets you create) it can easily become daunting if you have to manually transfer the icons into the <svg>. Fortunately, you don’t have to do that. Fabrice Weinberg created a Grunt plugin called grunt-svgstore which takes the icons in your SVG folder and generates the SVG sprites for you; all you have to do is just drop the sprites into your page and use the icons like we did earlier.
This technique works in all browsers supporting SVG. There seems to be a bug in Safari on iOS which causes the icons not to show up when the SVG sprite is defined at the bottom of the document after the <use> references to the icons, so it’s safest to include the sprite before you use the icons until this bug is fixed.
This technique has one disadvantage: the SVG sprite cannot be cached. We’re saving an extra HTTP request here but the browser cannot cache the image, so we aren’t speeding up any subsequent page loads by inlining the SVG. There must be a better way – and there is.
Styling the icons is possible, but getting deep into the styles becomes a bit harder owing to the nature of the contents of the <use> element – these contents are cloned into a shadow DOM, and hence selecting elements in CSS the traditional way is not possible. However, some techniques to work around that do exist, and give us slightly more styling flexibility. Animations work as expected.
Referencing an external SVG sprite in HTML
Instead of including the SVG inline in the document, you can reference the sprite and the icons inside it externally, taking advantage of fragment identifiers to select individual icons in the sprite.
For example, the above reference to the Twitter icon would look something like this instead:
<svg class="twitter-icon">
<use xlink:href="path/to/icons.svg#twitter-icon"></use>
<svg>
icons.svg is the name of the SVG file that contains all of our icons as symbols, and the fragment identifier #twitter-icon is the reference to the <symbol> wrapping the Twitter icon’s contents. Very convenient, isn’t it? The browser will request the sprite and then cache it, speeding up subsequent page loads. Win!
This technique also works in all browsers supporting SVG except Internet Explorer – not even IE9+ with SVG support permits this technique. No version of IE supports referencing an external SVG in <use>.
Fortunately (again), Jonathan Neil has created a plugin called svg4everybody which fills this gap in IE; you can reference an external sprite in <use> and also provide fallback for browsers that do not support SVG. However, it requires you to have the fallback images (PNG or JPEG, for example) available to do so. For details, refer to the plugin’s Github repository’s readme file.
CSS inline SVG sprites
Another way to create an SVG sprite is by inlining the SVG icons in a style sheet using data URIs, and providing fallback for non-supporting browsers – also within the CSS.
Using this approach, we’re turning the style sheet into the sprite that includes our icons. The style sheet is normally cached by the browser, so we have that concern out of the way.
This technique is put into practice in Filament Group’s icon system approach, which uses their Grunticon plugin – or its sister Grumpicon web app – for generating the necessary CSS for the sprite. As such, we’re going to cover this technique by following a workflow that uses one of these tools.
Again, we start with our icon SVG files. To focus on the actual spriting method and not on the tooling, I’ll go over the process of sprite creation using the Grumpicon web app, instead of the Grunticon plugin. Both tools generate the same resources that we’re going to use for the icon system. Whether you choose the web app or the Grunt set-up, after processing your SVG folder you’re going to end up with the same set of resources that we’ll be using throughout this section.
The first step is to drop your icons into the Grumpicon web app.
Grumpicon homepage screenshot.
The application will then show you a preview of your icons, and a download button will allow you to download the generated files. These files will contain everything you need for your icon system – all that’s left is for you to drop the generated files and code into your project as recommended and you’ll have your sprite and icons ready to use anywhere you want in your page.
Grumpicon generates five files and one folder in the downloaded package: a png folder containing PNG versions of your icons; three style sheets (that we’ll go over briefly); a loader script file; and preview.html which is a live example showing you the other files in action.
The script in the loader goes into the <head> of your page. This script handles browser and feature detection, and requests the necessary style sheet depending on browser support for SVG and base64 data URIs. If you view the source code of the preview page, you can see exactly how the script is added.
icons.data.svg.css is the style sheet that contains your icons – the sprite. The icons are embedded inline inside the style sheet using data URIs, and applied to elements of your choice as background images, using class names. For example:
.twitter-icon{
background-image: url('data:image/svg+xml;…'); /* the ellipsis is where the icon’s data would go */
background-repeat: no-repeat;
background-position: 50% 50%;
height: 2em;
width: 2em;
/* etc. */
}
Then, you only have to apply the twitter-icon class name to an element in your HTML to apply the icon as a background to it:
<span class="twitter-icon"></span>
And that’s all you need to do to get an icon on the page.
icons.data.svg.css, along with the other two style sheets and the png folder should be added to your CSS folder.
icons.data.png.css is the style sheet the script will load in browsers that don’t support SVG, such as IE8. Fallback for the inline SVG is provided as a base64-encoded PNG. For instance, the fallback for the Twitter icon from our example would look like so:
.twitter-icon{
background-image: url('data:image/png;base64;…’);
/* etc. */
}
icons.fallback.css is the style sheet required for browsers that don’t support base64-encoded PNGs – the PNG images are loaded as usual using the image’s URL. The script will load this style sheet for IE6 and IE7, for example.
.twitter-icon{
background-image: url(png/twitter-icon.png);
/* etc. */
}
This technique is very different from the previous one. The sprite in this case is literally the style sheet, not an SVG container, and the icon usage is very similar to that of a CSS sprite – the icons are provided as background images.
This technique has advantages and disadvantages. For the sake of brevity, I won’t go into further details, but the main limitations worth mentioning are that SVGs embedded as background images cannot be styled with CSS; and animations are restricted to those defined inside the <svg> for each icon. CSS interactions (such as hover effects) don’t work either. Thus, to apply an effect for an icon that changes its color on hover, for example, you’ll need to export a set of SVGs for each colour in order for Grumpicon to create matching fallback PNG images that can then be used for the animation.
For more details about the Grumpicon workflow, I recommend you check out “A Designer’s Guide to Grumpicon” on Filament Group’s website.
Using SVG fragment identifiers and views
This spriting technique is, again, different from the previous ones, and it is my personal favourite.
SVG comes with a standard way of cropping to a specific area in a particular SVG image. If you’ve ever worked with CSS sprites before then this definitely sounds familiar: it’s almost exactly what we do with CSS sprites – the image containing all of the icons is cropped, so to speak, to show only the one icon that we want in the background positioning area of the element, using background size and positioning properties.
Instead of using background properties, we’ll be using SVG’s viewBox attribute to crop our SVG to the specific icon we want.
What I like about this technique is that it is more visual than the previous ones. Using this technique, the SVG sprite is treated like an actual image containing other images (the icons), instead of treating it as a piece of code containing other code.
Again, our SVG icons are placed inside a main SVG container that is going to be our SVG sprite. If you’re working in a graphics editor, position or arrange your icons inside the canvas any way you want them to be, and then export the graphic as is. Of course, the less empty space there is in your SVG, the better.
In our example, the sprite contains three icons as shown in the following image. The sprite is open in Sketch. Notice how the SVG is just big enough to fit the icons inside it. It doesn’t have to be like this, but it’s cleaner this way.
Screenshot showing the SVG sprite containing our icons.
Now, suppose you want to display only the Instagram icon. Using the SVG viewBox attribute, we can crop the SVG to the icon. The Instagram icon is positioned at 64px along the positive x-axis, and zero pixels along the y-axis. It is also 32px by 32px in size.
Screenshot showing the position (offset) of the Instagram icon inside the SVG sprite, and its size.
Using this information, we can specify the value of the viewBox as: 64 0 32 32. This area of the view box contains only the Instagram icon. 64 0 specifies the top-left corner of the view box area, and 32 32 specify its dimensions.
Now, if we were to change the viewBox value on the SVG sprite to this value, only the Instagram icon will be visible inside the SVG viewport. Great. But how do we use this information to display the icon in our page using our sprite?
SVG comes with a native way to link to portions or areas of an image using fragment identifiers. Fragment identifiers are used to link into a particular view area of an SVG document. Thus, using a fragment identifier and the boundaries of the area that we want (from the viewBox), we can link to that area and display it.
For example, if you want to display the icon from the sprite using an <img> tag, you can reference the icon in the sprite like so:
<img src='uiIcons.svg#svgView(viewBox(64, 0, 32, 32))' alt="Settings icon"/>
The fragment identifier in the snippet above (#svgView(viewBox(64, 0, 32, 32))) is the important part. This will result in only the Instagram icon’s area of the sprite being displayed.
There is also another way to do this, using the SVG <view> element. The <view> element can be used to define a view area and then reference that area somewhere else. For example, to define the view box containing the Instagram icon, we can do the following:
<view id='instagram-icon' viewBox='64 0 32 32' />
Then, we can reference this view in our <img> element like this:
<img src='sprite.svg#instagram-icon' alt="Instagram icon" />
The best part about this technique – besides the ability to reference an external SVG and hence make use of browser caching – is that it allows us to use practically any SVG embedding technique and does not restrict us to specific tags.
It goes without saying that this feature can be used for more than just icon systems, owing to viewBox’s power in controlling an SVG’s viewable area.
SVG fragment identifiers have decent browser support, but the technique is buggy in Safari: there is a bug that causes problems when loading a server SVG file and then using fragment identifiers with it. Bear Travis has documented the issue and a workaround.
Where to go from here
Pick the technique that works best for your project. Each technique has its own pros and cons, relating to convenience and maintainability, performance, and styling and scripting. Each technique also requires its own fallback mechanism.
The spriting techniques mentioned here are not the only techniques available. Other methods exist, such as SVG stacks, and others may surface in future, but these are the three main ones today.
The third technique using SVG’s built-in viewBox features is my favourite, and with better browser support and fewer (ideally, no) bugs, I believe it is more likely to become the standard way to create and use SVG sprites. Fallback techniques can be created, of course, in one of many possible ways.
Do you use SVG for your icon system? If so, which is your favourite technique? Do you know or have worked with other ways for creating SVG sprites? |
2014 |
Sara Soueidan |
sarasoueidan |
2014-12-16T00:00:00+00:00 |
https://24ways.org/2014/an-overview-of-svg-sprite-creation-techniques/ |
code |
| 296 |
Animation in Design Systems |
Our modern front-end workflow has matured over time to include design systems and component libraries that help us stay organized, improve workflows, and simplify maintenance. These systems, when executed well, ensure proper documentation of the code available and enable our systems to scale with reduced communication conflicts.
But while most of these systems take a critical stance on fonts, colors, and general building blocks, their treatment of animation remains disorganized and ad-hoc. Let’s leverage existing structures and workflows to reduce friction when it comes to animation and create cohesive and performant user experiences.
Understand the importance of animation
Part of the reason we treat animation like a second-class citizen is that we don’t really consider its power. When users are scanning a website (or any environment or photo), they are attempting to build a spatial map of their surroundings. During this process, nothing quite commands attention like something in motion.
We are biologically trained to notice motion: evolutionarily speaking, our survival depends on it. For this reason, animation when done well can guide your users. It can aid and reinforce these maps, and give us a sense that we understand the UX more deeply. We retrieve information and put it back where it came from instead of something popping in and out of place.
“Where did that menu go? Oh it’s in there.”
For a deeper dive into how animation can connect disparate states, I wrote about the Importance of Context-Shifting in UX Patterns for CSS-Tricks.
An animation flow on mobile.
Animation also aids in perceived performance. Viget conducted a study where they measured user engagement with a standard loading GIF versus a custom animation. Customers were willing to wait almost twice as long for the custom loader, even though it wasn’t anything very fancy or crazy. Just by showing their users that they cared about them, they stuck around, and the bounce rates dropped.
14 second generic loading screen.22 second custom loading screen.
This also works for form submission. Giving your personal information over to an online process like a static form can be a bit harrowing. It becomes more harrowing without animation used as a signal that something is happening, and that some process is completing. That same animation can also entertain users and make them feel as though the wait isn’t as long.
Eli Fitch gave a talk at CSS Dev Conf called: “Perceived Performance: The Only Kind That Really Matters”, which is one of my favorite talk titles of all time. In it, he discussed how we tend to measure things like timelines and network requests because they are more quantifiable–and therefore easier to measure–but that measuring how a user feels when visiting the site is more important and worth the time and attention.
In his talk, he states “Humans over-estimate passive waits by 36%, per Richard Larson of MIT”. This means that if you’re not using animation to speed up how fast the wait time of a form submission loads, users are perceiving it to be much slower than the dev tools timeline is recording.
Reign it in
Unlike fonts, colors, and so on, we tend to add animation in as a last step, which leads to disorganized implementations that lack overall cohesion. If you asked a designer or developer if they would create a mockup or build a UI without knowing the fonts they were working with, they would dislike the idea. Not knowing the building blocks they’re working with means that the design can fall apart or the development can break with something so fundamental left out at the start. Good animation works the same way.
The first step in reigning in your use of animation is to perform an animation audit. Look at all the places you are using animation on your site, or the places you aren’t using animation but probably should. (Hint: perceived performance of a loader on a form submission can dramatically change your bounce rates.)
Not sure how to perform a good audit? Val Head has a great chapter on it in her book, Designing Interface Animations, which has of buckets of research and great ideas.
Even some beautiful component libraries that have animation in the docs make this mistake. You don’t need every kind of animation, just like you don’t need every kind of font. This bloats our code. Ask yourself questions like: do you really need a flip 180 degree animation? I can’t even conceive of a place on a typical UI where that would be useful, yet most component libraries that I’ve seen have a mixin that does just this.
Which leads to…
Have an opinion
Many people are confused about Material Design. They think that Material Design is Motion Design, mostly because they’ve never seen anyone take a stance on animation before and document these opinions well. But every time you use Material Design as your motion design language, people look at your site and think GOOGLE. Now that’s good branding.
By using Google’s motion design language and not your own, you’re losing out on a chance to be memorable on your own website.
What does having an opinion on motion look like in practice? It could mean you’ve decided that you never flip things. It could mean that your eases are always going to glide. In that instance, you would put your efforts towards finding an ease that looks “gliding” and pulling out any transform: scaleX(-1) animation you find on your site. Across teams, everyone knows not to spend time mocking up flipping animation (even if they’re working on an entirely different codebase), and to instead work on something that feels like it glides. You save time and don’t have to communicate again and again to make things feel cohesive.
Create good developer resources
Sometimes people don’t incorporate animation into a design system because they aren’t sure how, beyond the base hover states. All animation properties can be broken into interchangeable pieces. This allows developers and designers alike to mix and match and iterate quickly, while still staying in the correct language. Here are some recommendations (with code and a demo to follow):
Create timing units, similar to h1, h2, h3. In a system I worked on recently, I called these t1, t2, t3. T1 would be reserved for longer pieces, down to t5 which is a bit like h5 in that it’s the default (usually around .25 seconds or thereabouts).
Keep animation easings for entrance, exit, entrance emphasis and exit emphasis that people can commonly refer to. This, and the animation-fill-mode, are likely to be the only two properties that can be reused for the entrance and exit of the animation.
Use the animation-name property to define the keyframes for the animation itself. I would recommend starting with 5 or 6 before making a slew of them, and see if you need more. Writing 30 different animations might seem like a nice resource, but just like your color palette having too many can unnecessarily bulk up your codebase, and keep it from feeling cohesive. Think critically about what you need here.
See the Pen Modularized Animation for Component Libraries by Sarah Drasner (@sdras) on CodePen.
The example above is pared-down, but you can see how in a robust system, having pieces that are interchangeable cached across the whole system would save time for iterations and prototyping, not to mention make it easy to make adjustments for different feeling movement on the same animation easily.
One low hanging fruit might be a loader that leads to a success dialog. On a big site, you might have that pattern many times, so writing up a component that does only that helps you move faster while also allowing you to really zoom in and focus on that pattern. You avoid throwing something together at the last minute, or using a GIF, which are really heavy and mushy on retina. You can make singular pieces that look really refined and are reusable.
React and Vue Implementations are great for reusable components, as you can create a building block with a common animation pattern, and once created, it can be a resource for all. Remember to take advantage of things like props to allow for timing and easing adjustments like we have in the previous example!
Responsive
At the very least we should ensure that interaction also works well on mobile, but if we’d like to create interactions that take advantage of all of the gestures mobile has to offer, we can use libraries like zingtouch or hammer to work with swipe or multiple finger detection. With a bit of work, these can all be created through native detection as well.
Responsive web pages can specify initial-scale=1.0 in the meta tag so that the device is not waiting the required 300ms on the secondary tap before calling action. Interaction for touch events must either start from a larger touch-target (40px × 40px or greater) or use @media(pointer:coarse) as support allows.
Buy-in
Sometimes people don’t create animation resources simply because it gets deprioritized. But design systems were also something we once had to fight for, too. This year at CSS Dev Conf, Rachel Nabors demonstrated how to plot out animation wants vs. needs on a graph (reproduced with her permission) to help prioritize them:
This helps people you’re working with figure out the relative necessity and workload of the addition of these animations and think more critically about it. You’re also more likely to get something through if you’re proving that what you’re making is needed and can be reused.
Good compromises can be made this way: “we’re not going to go all out and create an animated ‘About Us’ page like you wanted, but I suppose we can let our users know their contact email went through with a small progress and success notification.”
Successfully pushing smaller projects through helps build trust with your team, and lets them see what this type of collaboration can look like. This builds up the type of relationship necessary to push through projects that are more involved. It can’t be overstressed that good communication is key.
Get started!
With these tools and good communication, we can make our codebases more efficient, performant, and feel better for our users. We can enhance the user experience on our sites, and create great resources for our teams to allow them to move more quickly while innovating beautifully. |
2016 |
Sarah Drasner |
sarahdrasner |
2016-12-16T00:00:00+00:00 |
https://24ways.org/2016/animation-in-design-systems/ |
code |
| 318 |
Auto-Selecting Navigation |
In the article Centered Tabs with CSS Ethan laid out a tabbed navigation system which can be centred on the page. A frequent requirement for any tab-based navigation is to be able to visually represent the currently selected tab in some way.
If you’re using a server-side language such as PHP, it’s quite easy to write something like class="selected" into your markup, but it can be even simpler than that.
Let’s take the navigation div from Ethan’s article as an example.
<div id="navigation">
<ul>
<li><a href="#"><span>Home</span></a></li>
<li><a href="#"><span>About</span></a></li>
<li><a href="#"><span>Our Work</span></a></li>
<li><a href="#"><span>Products</span></a></li>
<li class="last"><a href="#"><span>Contact Us</span></a></li>
</ul>
</div>
As you can see we have a standard unordered list which is then styled with CSS to look like tabs. By giving each tab a class which describes it’s logical section of the site, if we were to then apply a class to the body tag of each page showing the same, we could write a clever CSS selector to highlight the correct tab on any given page.
Sound complicated? Well, it’s not a trivial concept, but actually applying it is dead simple.
Modifying the markup
First thing is to place a class name on each li in the list:
<div id="navigation">
<ul>
<li class="home"><a href="#"><span>Home</span></a></li>
<li class="about"><a href="#"><span>About</span></a></li>
<li class="work"><a href="#"><span>Our Work</span></a></li>
<li class="products"><a href="#"><span>Products</span></a></li>
<li class="last contact"><a href="#"><span>Contact Us</span></a></li>
</ul>
</div>
Then, on each page of your site, apply the a matching class to the body tag to indicate which section of the site that page is in. For example, on your About page:
<body class="about">...</body>
Writing the CSS selector
You can now write a single CSS rule to match the selected tab on any given page. The logic is that you want to match the ‘about’ tab on the ‘about’ page and the ‘products’ tab on the ‘products’ page, so the selector looks like this:
body.home #navigation li.home,
body.about #navigation li.about,
body.work #navigation li.work,
body.products #navigation li.products,
body.contact #navigation li.contact{
... whatever styles you need to show the tab selected ...
}
So all you need to do when you create a new page in your site is to apply a class to the body tag to say which section it’s in. The CSS will do the rest for you – without any server-side help. |
2005 |
Drew McLellan |
drewmclellan |
2005-12-10T00:00:00+00:00 |
https://24ways.org/2005/auto-selecting-navigation/ |
code |
| 211 |
Automating Your Accessibility Tests |
Accessibility is one of those things we all wish we were better at. It can lead to a bunch of questions like: how do we make our site better? How do we test what we have done? Should we spend time each day going through our site to check everything by hand? Or just hope that everyone on our team has remembered to check their changes are accessible?
This is where automated accessibility tests can come in. We can set up automated tests and have them run whenever someone makes a pull request, and even alongside end-to-end tests, too.
Automated tests can’t cover everything however; only 20 to 50% of accessibility issues can be detected automatically. For example, we can’t yet automate the comparison of an alt attribute with an image’s content, and there are some screen reader tests that need to be carried out by hand too. To ensure our site is as accessible as possible, we will still need to carry out manual tests, and I will cover these later.
First, I’m going to explain how I implemented automated accessibility tests on Elsevier’s ecommerce pages, and share some of the lessons I learnt along the way.
Picking the right tool
One of the hardest, but most important parts of creating our automated accessibility tests was choosing the right tool.
We began by investigating aXe CLI, but soon realised it wouldn’t fit our requirements. It couldn’t check pages that required a visitor to log in, so while we could test our product pages, we couldn’t test any customer account pages. Instead we moved over to Pa11y. Its beforeScript step meant we could log into the site and test pages such as the order history.
The example below shows the how the beforeScript step completes a login form and then waits for the login to complete before testing the page:
beforeScript: function(page, options, next) {
// An example function that can be used to make sure changes have been confirmed before continuing to run Pa11y
function waitUntil(condition, retries, waitOver) {
page.evaluate(condition, function(err, result) {
if (result || retries < 1) {
// Once the changes have taken place continue with Pa11y testing
waitOver();
} else {
retries -= 1;
setTimeout(function() {
waitUntil(condition, retries, waitOver);
}, 200);
}
});
}
// The script to manipulate the page must be run with page.evaluate to be run within the context of the page
page.evaluate(function() {
const user = document.querySelector('#login-form input[name="email"]');
const password = document.querySelector('#login-form input[name="password"]');
const submit = document.querySelector('#login-form input[name="submit"]');
user.value = 'user@example.com';
password.value = 'password';
submit.click();
}, function() {
// Use the waitUntil function to set the condition, number of retries and the callback
waitUntil(function() {
return window.location.href === 'https://example.com';
}, 20, next);
});
}
The waitUntil callback allows the test to be delayed until our test user is successfully logged in.
Another thing to consider when picking a tool is the type of error messages it produces. aXe groups all elements with the same error together, so the list of issues is a lot easier to read, and it’s easier to identify the most commons problems. For example, here are some elements that have insufficient colour contrast:
Violation of "color-contrast" with 8 occurrences!
Ensures the contrast between foreground and background colors meets
WCAG 2 AA contrast ratio thresholds. Correct invalid elements at:
- #maincontent > .make_your_mark > div:nth-child(2) > p > span > span
- #maincontent > .make_your_mark > div:nth-child(4) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(2) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(4) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(6) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(8) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(10) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(12) > p > span > span
For details, see: https://dequeuniversity.com/rules/axe/2.5/color-contrast
aXe also provides links to their site where they discuss the best way to fix the problem.
In comparison, Pa11y lists each individual error which can lead to a very verbose list. However, it does provide helpful suggestions of how to fix problems, such as suggesting an alternative shade of a colour to use:
• Error: This element has insufficient contrast at this conformance level.
Expected a contrast ratio of at least 4.5:1, but text in this element has a contrast ratio of 2.96:1.
Recommendation: change text colour to #767676.
⎣ WCAG2AA.Principle1.Guideline1_4.1_4_3.G18.Fail
⎣ #maincontent > div:nth-child(10) > div:nth-child(8) > p > span > span
⎣ <span style="color:#969696">Featured products:</span>
Integrating into our build pipeline
We decided the perfect time to run our accessibility tests would be alongside our end-to-end tests. We have a Jenkins job that detects changes to our staging site and then triggers the end-to-end tests, and in turn our accessibility tests. Our Jenkins job retrieves the contents of a GitHub repository containing our Pa11y script file and npm package manifest.
Once Jenkins has cloned the repository, it installs any dependencies and executes the tests via:
npm install && npm test
Bundling the URLs to be tested into our test script means we don’t have a command line style test where we list each URL we wish to test in the Jenkins CLI. It’s an effective method but can also be cluttered, and obscure which URLs are being tested.
In the middle of the office we have a monitor displaying a Jenkins dashboard and from this we can see if the accessibility tests are passing or failing. Everyone in the team has access to the Jenkins logs and when the build fails they can see why and fix the issue.
Fixing the issues
As mentioned earlier, Pa11y can generate a long list of areas for improvement which can be very verbose and quite overwhelming. I recommend going through the list to see which issues occur most frequently and fix those first. For example, we initially had a lot of errors around colour contrast, and one shade of grey in particular. By making this colour darker, the number of errors decreased, and we could focus on the remaining issues.
Another thing I like to do is to tackle the quick fixes, such as adding alt text to images. These are small things that allow us to make an impact instantly, giving us time to fix more detailed concerns such as addressing tabindex issues, or speaking to our designers about changing the contrast of elements on the site.
Manual testing
Adding automated tests to check our site for accessibility is great, but as I mentioned earlier, this can only cover 20-50% of potential issues. To improve on this, we need to test by hand too, either by ourselves or by asking others.
One way we can test our site is to throw our mouse or trackpad away and interact with the site using only a keyboard. This allows us to check items such as tab order, and ensure menu items, buttons etc. can be used without a mouse. The commands may be different on different operating systems, but there are some great guides online for learning more about these.
It’s tempting to add alt text and aria-labels to make errors go away, but if they don’t make any sense, what use are they really? Using a screenreader we can check that alt text accurately represents the image. This is also a great way to double check that our ARIA roles make sense, and that they correctly identify elements and how to interact with them. When testing our site with screen readers, it’s important to remember that not all screen readers are the same and some may interact with our site differently to others.
Consider asking a range of people with different needs and abilities to test your site, too. People experience the web in numerous ways, be they permanent, temporary or even situational. They may interact with your site in ways you hadn’t even thought about, so this is a good way to broaden your knowledge and awareness.
Tips and tricks
One of our main issues with Pa11y is that it may find issues we don’t have the power to solve. A perfect example of this is the one pixel image Facebook injects into our site. So, we wrote a small function to go though such errors and ignore the ones that we cannot fix.
const test = pa11y({
....
hideElements: '#ratings, #js-bigsearch',
...
});
const ignoreErrors: string[] = [
'<img src="https://books.google.com/intl/en/googlebooks/images/gbs_preview_button1.gif" border="0" style="cursor: pointer;" class="lightbox-is-image">',
'<script type="text/javascript" id="">var USI_orderID=google_tag_mana...</script>',
'<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=123456789012345&ev=PageView&noscript=1">'
];
const filterResult = result => {
if (ignoreErrors.indexOf(result.context) > -1) {
return false;
}
return true;
};
Initially we wanted to focus on fixing the major problems, so we added a rule to ignore notices and warnings. This made the list or errors much smaller and allowed us focus on fixing major issues such as colour contrast and missing alt text. The ignored notices and warnings can be added in later after these larger issues have been resolved.
const test = pa11y({
ignore: [
'notice',
'warning'
],
...
});
Jenkins gotchas
While using Jenkins we encountered a few problems. Sometimes Jenkins would indicate a build had passed when in reality it had failed. This was because Pa11y had timed out due to PhantomJS throwing an error, or the test didn’t go past the first URL. Pa11y has recently released a new beta version that uses headless Chrome instead of PhantomJS, so hopefully these issues will less occur less often.
We tried a few approaches to solve these issues. First we added error handling, iterating over the array of test URLs so that if an unexpected error happened, we could catch it and exit the process with an error indicating that the job had failed (using process.exit(1)).
for (const url of urls) {
try {
console.log(url);
let urlResult = await run(url);
urlResult = urlResult.filter(filterResult);
urlResult.forEach(result => console.log(result));
}
catch (e) {
console.log('Error:', e);
process.exit(1);
}
}
We also had issues with unhandled rejections sometimes caused by a session disconnecting or similar errors. To avoid Jenkins indicating our site was passing with 100% accessibility, when in reality it had not executed any tests, we instructed Jenkins to fail the job when an unhandled rejection or uncaught exception occurred:
process.on('unhandledRejection', (reason, p) => {
console.log('Unhandled Rejection at:', p, 'reason:', reason);
process.exit(1);
});
process.on('uncaughtException', (err) => {
console.log('Caught exception: ${err}n');
process.exit(1);
});
Now it’s your turn
That’s it! That’s how we automated accessibility testing for Elsevier ecommerce pages, allowing us to improve our site and make it more accessible for everyone. I hope our experience can help you automate accessibility tests on your own site, and bring the web a step closer to being accessible to all. |
2017 |
Seren Davies |
serendavies |
2017-12-07T00:00:00+00:00 |
https://24ways.org/2017/automating-your-accessibility-tests/ |
code |
| 319 |
Avoiding CSS Hacks for Internet Explorer |
Back in October, IEBlog issued a call to action, asking developers to clean up their CSS hacks for IE7 testing. Needless to say, a lot of hubbub ensued… both on IEBlog and elsewhere. My contribution to all of the noise was to suggest that developers review their code and use good CSS hacks. But what makes a good hack?
Tantek Çelik, the Godfather of CSS hacks, gave us the answer by explaining how CSS hacks should be designed. In short, they should (1) be valid, (2) target only old/frozen/abandoned user-agents/browsers, and (3) be ugly. Tantek also went on to explain that using a feature of CSS is not a hack.
Now, I’m not a frequent user of CSS hacks, but Tantek’s post made sense to me. In particular, I felt it gave developers direction on how we should be coding to accommodate that sometimes troublesome browser, Internet Explorer. But what I’ve found, through my work with other developers, is that there is still much confusion over the use of CSS hacks and IE. Using examples from the code I’ve seen recently, allow me to demonstrate how to clean up some IE-specific CSS hacks.
The two hacks that I’ve found most often in the code I’ve seen and worked with are the star html bug and the underscore hack. We know these are both IE-specific by checking Kevin Smith’s CSS Filters chart. Let’s look at each of these hacks and see how we can replace them with the same CSS feature-based solution.
The star html bug
This hack violates Tantek’s second rule as it targets current (and future) UAs. I’ve seen this both as a stand alone rule, as well as an override to some other rule in a style sheet. Here are some code samples:
* html div#header {margin-top:-3px;}
.promo h3 {min-height:21px;}
* html .promo h3 {height:21px;}
The underscore hack
This hack violates Tantek’s first two rules: it’s invalid (according to the W3C CSS Validator) and it targets current UAs. Here’s an example:
ol {padding:0; _padding-left:5px;}
Using child selectors
We can use the child selector to replace both the star html bug and underscore hack. Here’s how:
Write rules with selectors that would be successfully applied to all browsers. This may mean starting with no declarations in your rule!
div#header {}
.promo h3 {}
ol {padding:0;}
To these rules, add the IE-specific declarations.
div#header {margin-top:-3px;}
.promo h3 {height:21px;}
ol {padding:0 0 0 5px;}
After each rule, add a second rule. The selector of the second rule must use a child selector. In this new rule, correct any IE-specific declarations previously made.
div#header {margin-top:-3px;}
body > div#header {margin-top:0;}
.promo h3 {height:21px;}
.promo > h3 {height:auto; min-height:21px;}
ol {padding:0 0 0 5px;}
html > body ol {padding:0;}
Voilà – no more hacks! There are a few caveats to this that I won’t go into… but assuming you’re operating in strict mode and barring any really complicated stuff you’re doing in your code, your CSS will still render perfectly across browsers. And while this may make your CSS slightly heftier in size, it should future-proof it for IE7 (or so I hope). Happy holidays! |
2005 |
Kimberly Blessing |
kimberlyblessing |
2005-12-17T00:00:00+00:00 |
https://24ways.org/2005/avoiding-css-hacks-for-internet-explorer/ |
code |
| 63 |
Be Fluid with Your Design Skills: Build Your Own Sites |
Just five years ago in 2010, when we were all busy trying to surprise and delight, learning CSS3 and trying to get whole websites onto one page, we had a poster on our studio wall. It was entitled ‘Designers Vs Developers’, an infographic that showed us the differences between the men(!) who created websites.
Designers wore skinny jeans and used Macs and developers wore cargo pants and brought their own keyboards to work. We began to learn that designers and developers were not only doing completely different jobs but were completely different people in every way. This opinion was backed up by hundreds of memes, millions of tweets and pages of articles which used words like void and battle and versus.
Thankfully, things move quickly in this industry; the wide world of web design has moved on in the last five years. There are new devices, technologies, tools – and even a few women. Designers have been helped along by great apps, software, open source projects, conferences, and a community of people who, to my unending pride, love to share their knowledge and their work.
So the world has moved on, and if Miley Cyrus, Ruby Rose and Eliot Sumner are identifying as gender fluid (an identity which refers to a gender which varies over time or is a combination of identities), then I would like to come out as discipline fluid!
OK, I will probably never identify as a developer, but I will identify as fluid! How can we be anything else in an industry that moves so quickly? That’s how we should think of our skills, our interests and even our job titles. After all, Steve Jobs told us that “Design is not just what it looks like and feels like. Design is how it works.” Sorry skinny-jean-wearing designers – this means we’re all designing something together. And it’s not just about knowing the right words to use: you have to know how it feels. How it feels when you make something work, when you fix that bug, when you make it work on IE.
Like anything in life, things run smoothly when you make the effort to share experiences, empathise and deeply understand the needs of others. How can designers do that if they’ve never built their own site? I’m not talking the big stuff, I’m talking about your portfolio site, your mate’s business website, a website for that great idea you’ve had. I’m talking about doing it yourself to get an unique insight into how it feels.
We all know that designers and developers alike love an <ol>, so here it is.
Ten reasons designers should be fluid with their skills and build their own sites
1. It’s never been easier
Now here’s where the definition of ‘build’ is going to get a bit loose and people are going to get angry, but when I say it’s never been easier I mean because of the existence of apps and software like WordPress, Squarespace, Tumblr, et al. It’s easy to make something and get it out there into the world, and these are all gateway drugs to hard coding!
2. You’ll understand how it feels
How it feels to be so proud that something actually works that you momentarily don’t notice if the kerning is off or the padding is inconsistent. How it feels to see your site appear when you’ve redirected a URL. How it feels when you just can’t work out where that one extra space is in a line of PHP that has killed your whole site.
3. It makes you a designer
Not a better designer, it makes you a designer when you are designing how things look and how they work.
4. You learn about movement
Photoshop and Sketch just don’t cut it yet. Until you see your site in a browser or your app on a phone, it’s hard to imagine how it moves. Building your own sites shows you that it’s not just about how the content looks on the screen, but how it moves, interacts and feels.
5. You make techie friends
All the tutorials and forums in the world can’t beat your network of techie friends. Since I started working in web design I have worked with, sat next to, and co-created with some of the greatest developers. Developers who’ve shared their knowledge, encouraged me to build things, patiently explained HTML, CSS, servers, divs, web fonts, iOS development. There has been no void, no versus, very few battles; just people who share an interest and love of making things.
6. You will own domain names
When something is paid for, online and searchable then it’s real and you’ve got to put the work in. Buying domains has taught me how to stop procrastinating, but also about DNS, FTP, email, and how servers work.
7. People will ask you to do things
Learning about code and development opens a whole new world of design. When you put your own personal websites and projects out there people ask you to do more things. OK, so sometimes those things are “Make me a website for free”, but more often it’s cool things like “Come and speak at my conference”, “Write an article for my magazine” and “Collaborate with me.”
8. The young people are coming!
They love typography, they love print, they love layout, but they’ve known how to put a website together since they started their first blog aged five and they show me clever apps they’ve knocked together over the weekend! They’re new, they’re fluid, and they’re better than us!
9. Your portfolio is your portfolio
OK, it’s an obvious one, but as designers our work is our CV, our legacy! We need to show our skill, our attention to detail and our creativity in the way we showcase our work. Building your portfolio is the best way to start building your own websites. (And please be that designer who’s bothered to work out how to change the Squarespace favicon!)
10. It keeps you fluid!
Building your own websites is tough. You’ll never be happy with it, you’ll constantly be updating it to keep up with technology and fashion, and by the time you’ve finished it you’ll want to start all over again. Perfect for forcing you to stay up-to-date with what’s going on in the industry.
</ol> |
2015 |
Ros Horner |
roshorner |
2015-12-12T00:00:00+00:00 |
https://24ways.org/2015/be-fluid-with-your-design-skills-build-your-own-sites/ |
code |
| 64 |
Being Responsive to the Small Things |
It’s that time of the year again to trim the tree with decorations. Or maybe a DOM tree?
Any web page is made of HTML elements that lay themselves out in a tree structure. We start at the top and then have multiple branches with branches that branch out from there.
To decorate our tree, we use CSS to specify which branches should receive the tinsel we wish to adorn upon it. It’s all so lovely.
In years past, this was rather straightforward. But these days, our trees need to be versatile. They need to be responsive!
Responsive web design is pretty wonderful, isn’t it? Based on our viewport, we can decide how elements on the page should change their appearance to accommodate various constraints using media queries.
Clearleft have a delightfully clean and responsive site
Alas, it’s not all sunshine, lollipops, and rainbows.
With complex layouts, we may have design chunks — let’s call them components — that appear in different contexts. Each context may end up providing its own constraints on the design, both in its default state and in its possibly various responsive states.
Media queries, however, limit us to the context of the entire viewport, not individual containers on the page. For every container our component lives in, we need to specify how to rearrange things in that context. The more complex the system, the more contexts we need to write code for.
@media (min-width: 800px) {
.features > .component { }
.sidebar > .component {}
.grid > .component {}
}
Each new component and each new breakpoint just makes the entire system that much more difficult to maintain.
@media (min-width: 600px) {
.features > .component { }
.grid > .component {}
}
@media (min-width: 800px) {
.features > .component { }
.sidebar > .component {}
.grid > .component {}
}
@media (min-width: 1024px) {
.features > .component { }
}
Enter container queries
Container queries, also known as element queries, allow you to specify conditional CSS based on the width (or maybe height) of the container that an element lives in. In doing so, you no longer have to consider the entire page and the interplay of all the elements within.
With container queries, you’ll be able to consider the breakpoints of just the component you’re designing. As a result, you end up specifying less code and the components you develop have fewer dependencies on the things around them. (I guess that makes your components more independent.)
Awesome, right?
There’s only one catch.
Browsers can’t do container queries. There’s not even an official specification for them yet. The Responsive Issues (née Images) Community Group is looking into solving how such a thing would actually work.
See, container queries are tricky from an implementation perspective. The contents of a container can affect the size of the container. Because of this, you end up with troublesome circular references.
For example, if the width of the container is under 500px then the width of the child element should be 600px, and if the width of the container is over 500px then the width of the child element should be 400px.
Can you see the dilemma? When the container is under 500px, the child element resizes to 600px and suddenly the container is 600px. If the container is 600px, then the child element is 400px! And so on, forever. This is bad.
I guess we should all just go home and sulk about how we just got a pile of socks when we really wanted the Millennium Falcon.
Our saviour this Christmas: JavaScript
The three wise men — Tim Berners-Lee, Håkon Wium Lie, and Brendan Eich — brought us the gifts of HTML, CSS, and JavaScript.
To date, there are a handful of open source solutions to fill the gap until a browser implementation sees the light of day.
Elementary by Scott Jehl
ElementQuery by Tyson Matanich
EQ.js by Sam Richards
CSS Element Queries from Marcj
Using any of these can sometimes feel like your toy broke within ten minutes of unwrapping it.
Each take their own approach on how to specify the query conditions. For example, Elementary, the smallest of the group, only supports min-width declarations made in a :before selector.
.mod-foo:before {
content: “300 410 500”;
}
The script loops through all the elements that you specify, reading the content property and then setting an attribute value on the HTML element, allowing you to use CSS to style that condition.
.mod-foo[data-minwidth~="300"] {
background: blue;
}
To get the script to run, you’ll need to set up event handlers for when the page loads and for when it resizes.
window.addEventListener( "load", window.elementary, false );
window.addEventListener( "resize", window.elementary, false );
This works okay for static sites but breaks down on pages where elements can expand or contract, or where new content is dynamically inserted.
In the case of EQ.js, the implementation requires the creation of the breakpoints in the HTML. That means that you have implementation details in HTML, JavaScript, and CSS. (Although, with the JavaScript, once it’s in the build system, it shouldn’t ever be much of a concern unless you’re tracking down a bug.)
Another problem you may run into is the use of content delivery networks (CDNs) or cross-origin security issues. The ElementQuery and CSS Element Queries libraries need to be able to read the CSS file. If you are unable to set up proper cross-origin resource sharing (CORS) headers, these libraries won’t help.
At Shopify, for example, we had all of these problems. The admin that store owners use is very dynamic and the CSS and JavaScript were being loaded from a CDN that prevented the JavaScript from reading the CSS.
To go responsive, the team built their own solution — one similar to the other scripts above, in that it loops through elements and adds or removes classes (instead of data attributes) based on minimum or maximum width.
The caveat to this particular approach is that the declaration of breakpoints had to be done in JavaScript.
elements = [
{ ‘module’: “.carousel”, “className”:’alpha’, minWidth: 768, maxWidth: 1024 },
{ ‘module’: “.button”, “className”:’beta’, minWidth: 768, maxWidth: 1024 } ,
{ ‘module’: “.grid”, “className”:’cappa’, minWidth: 768, maxWidth: 1024 }
]
With that done, the script then had to be set to run during various events such as inserting new content via Ajax calls. This sometimes reveals itself in flashes of unstyled breakpoints (FOUB). An unfortunate side effect but one largely imperceptible.
Using this approach, however, allowed the Shopify team to make the admin responsive really quickly. Each member of the team was able to tackle the responsive story for a particular component without much concern for how all the other components would react.
Each element responds to its own breakpoint that would amount to dozens of breakpoints using traditional breakpoints. This approach allows for a truly fluid and adaptive interface for all screens.
Christmas is over
I wish I were the bearer of greater tidings and cheer. It’s not all bad, though. We may one day see browsers implement container queries natively. At which point, we shall all rejoice! |
2015 |
Jonathan Snook |
jonathansnook |
2015-12-19T00:00:00+00:00 |
https://24ways.org/2015/being-responsive-to-the-small-things/ |
code |
| 128 |
Boost Your Hyperlink Power |
There are HTML elements and attributes that we use every day. Headings, paragraphs, lists and images are the mainstay of every Web developer’s toolbox. Perhaps the most common tool of all is the anchor. The humble a element is what joins documents together to create the gloriously chaotic collection we call the World Wide Web.
Anatomy of an Anchor
The power of the anchor element lies in the href attribute, short for hypertext reference. This creates a one-way link to another resource, usually another page on the Web:
<a href="http://allinthehead.com/">
The href attribute sits in the opening a tag and some descriptive text sits between the opening and closing tags:
<a href="http://allinthehead.com/">Drew McLellan</a>
“Whoop-dee-freakin’-doo,” I hear you say, “this is pretty basic stuff” – and you’re quite right. But there’s more to the anchor element than just the href attribute.
The Theory of relativity
You might be familiar with the rel attribute from the link element. I bet you’ve got something like this in the head of your documents:
<link rel="stylesheet" type="text/css" media="screen" href="styles.css" />
The rel attribute describes the relationship between the linked document and the current document. In this case, the value of rel is “stylesheet”. This means that the linked document is the stylesheet for the current document: that’s its relationship.
Here’s another common use of rel:
<link rel="alternate" type="application/rss+xml" title="my RSS feed" href="index.xml" />
This describes the relationship of the linked file – an RSS feed – as “alternate”: an alternate view of the current document.
Both of those examples use the link element but you are free to use the rel attribute in regular hyperlinks. Suppose you’re linking to your RSS feed in the body of your page:
Subscribe to <a href="index.xml">my RSS feed</a>.
You can add extra information to this anchor using the rel attribute:
Subscribe to <a href="index.xml" rel="alternate" type="application/rss+xml">my RSS feed</a>.
There’s no prescribed list of values for the rel attribute so you can use whatever you decide is semantically meaningful. Let’s say you’ve got a complex e-commerce application that includes a link to a help file. You can explicitly declare the relationship of the linked file as being “help”:
<a href="help.html" rel="help">need help?</a>
Elemental Microformats
Although it’s completely up to you what values you use for the rel attribute, some consensus is emerging in the form of microformats. Some of the simplest microformats make good use of rel. For example, if you are linking to a license that covers the current document, use the rel-license microformat:
Licensed under a <a href="http://creativecommons.org/licenses/by/2.0/" rel="license">Creative Commons attribution license</a>
That describes the relationship of the linked document as “license.”
The rel-tag microformat goes a little further. It uses rel to describe the final part of the URL of the linked file as a “tag” for the current document:
Learn more about <a href="http://en.wikipedia.org/wiki/Microformats" rel="tag">semantic markup</a>
This states that the current document is being tagged with the value “Microformats.”
XFN, which stands for XHTML Friends Network, is a way of describing relationships between people:
<a href="http://allinthehead.com/" rel="friend">Drew McLellan</a>
This microformat makes use of a very powerful property of the rel attribute. Like the class attribute, rel can take multiple values, separated by spaces:
<a href="http://allinthehead.com/" rel="friend met colleague">Drew McLellan</a>
Here I’m describing Drew as being a friend, someone I’ve met, and a colleague (because we’re both Web monkies).
You Say You Want a revolution
While rel describes the relationship of the linked resource to the current document, the rev attribute describes the reverse relationship: it describes the relationship of the current document to the linked resource. Here’s an example of a link that might appear on help.html:
<a href="shoppingcart.html" rev="help">continue shopping</a>
The rev attribute declares that the current document is “help” for the linked file.
The vote-links microformat makes use of the rev attribute to allow you to qualify your links. By using the value “vote-for” you can describe your document as being an endorsement of the linked resource:
I agree with <a href="http://richarddawkins.net/home" rev="vote-for">Richard Dawkins</a>.
There’s a corresponding vote-against value. This means that you can link to a document but explicitly state that you don’t agree with it.
I agree with <a href="http://richarddawkins.net/home" rev="vote-for">Richard Dawkins</a>
about those <a href="http://www.icr.org/" rev="vote-against">creationists</a>.
Of course there’s nothing to stop you using both rel and rev on the same hyperlink:
<a href="http://richarddawkins.net/home" rev="vote-for" rel="muse">Richard Dawkins</a>
The Wisdom of Crowds
The simplicity of rel and rev belies their power. They allow you to easily add extra semantic richness to your hyperlinks. This creates a bounty that can be harvested by search engines, aggregators and browsers. Make it your New Year’s resolution to make friends with these attributes and extend the power of hypertext. |
2006 |
Jeremy Keith |
jeremykeith |
2006-12-18T00:00:00+00:00 |
https://24ways.org/2006/boost-your-hyperlink-power/ |
code |
| 182 |
Breaking Out The Edges of The Browser |
HTML5 contains more than just the new entities for a more meaningful document, it also contains an arsenal of JavaScript APIs. So many in fact, that some APIs have outgrown the HTML5 spec’s backyard and have been sent away to grow up all on their own and been given the prestigious honour of being specs in their own right.
So when I refer to (bendy finger quote) “HTML5”, I mean the HTML5 specification and a handful of other specifications that help us authors build web applications.
Examples of those specs I would include in the umbrella term would be: geolocation, web storage, web databases, web sockets and web workers, to name a few.
For all you guys and gals, on this special 2009 series of 24 ways, I’m just going to focus on data storage and offline applications: boldly taking your browser where no browser has gone before!
Web Storage
The Web Storage API is basically cookies on steroids, a unhealthy dosage of steroids. Cookies are always a pain to work with. First of all you have the problem of setting, changing and deleting them. Typically solved by Googling and blindly relying on PPK’s solution. If that wasn’t enough, there’s the 4Kb limit that some of you have hit when you really don’t want to.
The Web Storage API gets around all of the hoops you have to jump through with cookies. Storage supports around 5Mb of data per domain (the spec’s recommendation, but it’s open to the browsers to implement anything they like) and splits in to two types of storage objects:
sessionStorage – available to all pages on that domain while the window remains open
localStorage – available on the domain until manually removed
Support
Ignoring beta browsers for our support list, below is a list of the major browsers and their support for the Web Storage API:
Latest: Internet Explorer, Firefox, Safari (desktop & mobile/iPhone)
Partial: Google Chrome (only supports localStorage)
Not supported: Opera (as of 10.10)
Usage
Both sessionStorage and localStorage support the same interface for accessing their contents, so for these examples I’ll use localStorage.
The storage interface includes the following methods:
setItem(key, value)
getItem(key)
key(index)
removeItem(key)
clear()
In the simple example below, we’ll use setItem and getItem to store and retrieve data:
localStorage.setItem('name', 'Remy');
alert( localStorage.getItem('name') );
Using alert boxes can be a pretty lame way of debugging. Conveniently Safari (and Chrome) include database tab in their debugging tools (cmd+alt+i), so you can get a visual handle on the state of your data:
Viewing localStorage
As far as I know only Safari has this view on stored data natively in the browser. There may be a Firefox plugin (but I’ve not found it yet!) and IE… well that’s just IE.
Even though we’ve used setItem and getItem, there’s also a few other ways you can set and access the data.
In the example below, we’re accessing the stored value directly using an expando and equally, you can also set values this way:
localStorage.name = "Remy";
alert( localStorage.name ); // shows "Remy"
The Web Storage API also has a key method, which is zero based, and returns the key in which data has been stored. This should also be in the same order that you set the keys, for example:
alert( localStorage.getItem(localStorage.key(0)) );
// shows "Remy"
I mention the key() method because it’s not an unlikely name for a stored value. This can cause serious problems though.
When selecting the names for your keys, you need to be sure you don’t take one of the method names that are already on the storage object, like key, clear, etc. As there are no warnings when you try to overwrite the methods, it means when you come to access the key() method, the call breaks as key is a string value and not a function.
You can try this yourself by creating a new stored value using localStorage.key = "foo" and you’ll see that the Safari debugger breaks because it relies on the key() method to enumerate each of the stored values.
Usage Notes
Currently all browsers only support storing strings. This also means if you store a numeric, it will get converted to a string:
localStorage.setItem('count', 31);
alert(typeof localStorage.getItem('count'));
// shows "string"
This also means you can’t store more complicated objects natively with the storage objects. To get around this, you can use Douglas Crockford’s JSON parser (though Firefox 3.5 has JSON parsing support baked in to the browser – yay!) json2.js to convert the object to a stringified JSON object:
var person = {
name: 'Remy',
height: 'short',
location: 'Brighton, UK'
};
localStorage.setItem('person', JSON.stringify(person));
alert( JSON.parse(localStorage.getItem('person')).name );
// shows "Remy"
Alternatives
There are a few solutions out there that provide storage solutions that detect the Web Storage API, and if it’s not available, fall back to different technologies (for instance, using a flash object to store data). One comprehensive version of this is Dojo’s storage library. I’m personally more of a fan of libraries that plug missing functionality under the same namespace, just as Crockford’s JSON parser does (above).
For those interested it what that might look like, I’ve mocked together a simple implementation of sessionStorage. Note that it’s incomplete (because it’s missing the key method), and it could be refactored to not using the JSON stringify (but you would need to ensure that the values were properly and safely encoded):
// requires json2.js for all browsers other than Firefox 3.5
if (!window.sessionStorage && JSON) {
window.sessionStorage = (function () {
// window.top.name ensures top level, and supports around 2Mb
var data = window.top.name ? JSON.parse(window.top.name) : {};
return {
setItem: function (key, value) {
data[key] = value+""; // force to string
window.top.name = JSON.stringify(data);
},
removeItem: function (key) {
delete data[key];
window.top.name = JSON.stringify(data);
},
getItem: function (key) {
return data[key] || null;
},
clear: function () {
data = {};
window.top.name = '';
}
};
})();
}
Now that we’ve cracked the cookie jar with our oversized Web Storage API, let’s have a look at how we take our applications offline entirely.
Offline Applications
Offline applications is (still) part of the HTML5 specification. It allows developers to build a web app and have it still function without an internet connection. The app is access via the same URL as it would be if the user were online, but the contents (or what the developer specifies) is served up to the browser from a local cache. From there it’s just an everyday stroll through open web technologies, i.e. you still have access to the Web Storage API and anything else you can do without a web connection.
For this section, I’ll refer you to a prototype demo I wrote recently of a contrived Rubik’s cube (contrived because it doesn’t work and it only works in Safari because I’m using 3D transforms).
Offline Rubik’s cube
Support
Support for offline applications is still fairly limited, but the possibilities of offline applications is pretty exciting, particularly as we’re seeing mobile support and support in applications such as Fluid (and I would expect other render engine wrapping apps).
Support currently, is as follows:
Latest: Safari (desktop & mobile/iPhone)
Sort of: Firefox‡
Not supported: Internet Explorer, Opera, Google Chrome
‡ Firefox 3.5 was released to include offline support, but in fact has bugs where it doesn’t work properly (certainly on the Mac), Minefield (Firefox beta) has resolved the bug.
Usage
The status of the application’s cache can be tested from the window.applicationCache object. However, we’ll first look at how to enable your app for offline access.
You need to create a manifest file, which will tell the browser what to cache, and then we point our web page to that cache:
<!DOCTYPE html>
<html manifest="remy.manifest">
<!-- continues ... -->
For the manifest to be properly read by the browser, your server needs to serve the .manifest files as text/manifest by adding the following to your mime.types:
text/cache-manifest manifest
Next we need to populate our manifest file so the browser can read it:
CACHE MANIFEST
/demo/rubiks/index.html
/demo/rubiks/style.css
/demo/rubiks/jquery.min.js
/demo/rubiks/rubiks.js
# version 15
The first line of the manifest must read CACHE MANIFEST. Then subsequent lines tell the browser what to cache.
The HTML5 spec recommends that you include the calling web page (in my case index.html), but it’s not required. If I didn’t include index.html, the browser would cache it as part of the offline resources.
These resources are implicitly under the CACHE namespace (which you can specify any number of times if you want to).
In addition, there are two further namespaces: NETWORK and FALLBACK.
NETWORK is a whitelist namespace that tells the browser not to cache this resource and always try to request it through the network.
FALLBACK tells the browser that whilst in offline mode, if the resource isn’t available, it should return the fallback resource.
Finally, in my example I’ve included a comment with a version number. This is because once you include a manifest, the only way you can tell the browser to reload the resources is if the manifest contents changes. So I’ve included a version number in the manifest which I can change forcing the browser to reload all of the assets.
How it works
If you’re building an app that makes use of the offline cache, I would strongly recommend that you add the manifest last. The browser implementations are very new, so can sometimes get a bit tricky to debug since once the resources are cached, they really stick in the browser.
These are the steps that happen during a request for an app with a manifest:
Browser: sends request for your app.html
Server: serves all associated resources with app.html – as normal
Browser: notices that app.html has a manifest, it re-request the assets in the manifest
Server: serves the requested manifest assets (again)
Browser: window.applicationCache has a status of UPDATEREADY
Browser: reloads
Browser: only request manifest file (which doesn’t show on the net requests panel)
Server: responds with 304 Not Modified on the manifest file
Browser: serves all the cached resources locally
What might also add confusion to this process, is that the way the browsers work (currently) is if there is a cache already in place, it will use this first over updated resources. So if your manifest has changed, the browser will have already loaded the offline cache, so the user will only see the updated on the next reload.
This may seem a bit convoluted, but you can also trigger some of this manually through the applicationCache methods which can ease some of this pain.
If you bind to the online event you can manually try to update the offline cache. If the cache has then updated, swap the updated resources in to the cache and the next time the app loads it will be up to date. You could also prompt your user to reload the app (which is just a refresh) if there’s an update available.
For example (though this is just pseudo code):
addEvent(applicationCache, 'updateready', function () {
applicationCache.swapCache();
tellUserToRefresh();
});
addEvent(window, 'online', function () {
applicationCache.update();
});
Breaking out of the Browser
So that’s two different technologies that you can use to break out of the traditional browser/web page model and get your apps working in a more application-ny way.
There’s loads more in the HTML5 and non-HTML5 APIs to play with, so take your Christmas break to check them out! |
2009 |
Remy Sharp |
remysharp |
2009-12-02T00:00:00+00:00 |
https://24ways.org/2009/breaking-out-the-edges-of-the-browser/ |
code |
| 70 |
Bringing Your Code to the Streets |
— or How to Be a Street VJ
Our amazing world of web code is escaping out of the browser at an alarming rate and appearing in every aspect of the environment around us. Over the past few years we’ve already seen JavaScript used server-side, hardware coded with JavaScript, a rise of native style and desktop apps created with HTML, CSS and JavaScript, and even virtual reality (VR) is getting its fair share of front-end goodness.
You can go ahead and play with JavaScript-powered hardware such as the Tessel or the Espruino to name a couple. Just check out the Tessel project page to see JavaScript in the world of coffee roasting or sleep tracking your pet. With the rise of the internet of things, JavaScript can be seen collecting information on flooding among other things. And if that’s not enough ‘outside the browser’ implementations, Node.js servers can even be found in aircraft!
I previously mentioned VR and with three.js’s extra StereoEffect.js module it’s relatively simple to get browser 3D goodness to be Google Cardboard-ready, and thus set the stage for all things JavaScript and VR. It’s been pretty popular in the art world too, with interactive works such as Seb Lee-Delisle’s Lunar Trails installation, featuring the old arcade game Lunar Lander, which you can now play in your browser while others watch (it is the web after all). The Science Museum in London held Chrome Web Lab, an interactive exhibition featuring five experiments, showcasing the magic of the web. And it’s not even the connectivity of the web that’s being showcased; we can even take things offline and use web code for amazing things, such as fighting Ebola.
One thing is for sure, JavaScript is awesome. Hell, if you believe those telly programs (as we all do), JavaScript can even take down the stock market, purely through the witchcraft of canvas! Go JavaScript!
Now it’s our turn
So I wanted to create a little project influenced by this theme, and as it’s Christmas, take it to the streets for a little bit of party fun! Something that could take code anywhere. Here’s how I made a portable visual projection pack, a piece of video mixing software and created some web-coded street art.
Step one: The equipment
You will need:
One laptop: with HDMI output and a modern browser installed, such as Google Chrome.
One battery-powered mini projector: I’ve used a Texas Instruments DLP; for its 120 lumens it was the best cost-to-lumens ratio I could find.
One MIDI controller (optional): mine is an ICON iDJ as it suits mixing visuals. However, there is more affordable hardware on the market such as an Akai LPD8 or a Korg nanoPAD2. As you’ll see in the article, this is optional as it can be emulated within the software.
A case to carry it all around in.
Step two: The software
The projected visuals, I imagined, could be anything you can create within a browser, whether that be simple HTML and CSS, images, videos, SVG or canvas. The only requirement I have is that they move or change with sound and that I can mix any one visual into another.
You may remember a couple of years ago I created a demo on this very site, allowing audio-triggered visuals from the ambient sounds your device mic was picking up. That was a great starting point – I used that exact method to pick up the audio and thus the first requirement was complete. If you want to see some more examples of visuals I’ve put together for this, there’s a showcase on CodePen.
The second requirement took a little more thought. I needed two screens, which could at any point show any of the visuals I had coded, but could be mixed from one into the other and back again. So let’s start with two divs, both absolutely positioned so they’re on top of each other, but at the start the second screen’s opacity is set to zero.
Now all we need is a slider, which when moved from one side to the other slowly sets the second screen’s opacity to 1, thereby fading it in.
See the Pen Mixing Screens (Software Version) by Rumyra (@Rumyra) on CodePen.
Mixing Screens (CodePen)
As you saw above, I have a MIDI controller and although the software method works great, I’d quite like to make use of this nifty piece of kit. That’s easily done with the Web MIDI API. All I need to do is call it, and when I move one of the sliders on the controller (I’ve allocated the big cross fader in the middle for this), pick up on the change of value and use that to control the opacity instead.
var midi, data;
// start talking to MIDI controller
if (navigator.requestMIDIAccess) {
navigator.requestMIDIAccess({
sysex: false
}).then(onMIDISuccess, onMIDIFailure);
} else {
alert(“No MIDI support in your browser.”);
}
// on success
function onMIDISuccess(midiData) {
// this is all our MIDI data
midi = midiData;
var allInputs = midi.allInputs.values();
// loop over all available inputs and listen for any MIDI input
for (var input = allInputs.next(); input && !input.done; input = allInputs.next()) {
// when a MIDI value is received call the onMIDIMessage function
input.value.onmidimessage = onMIDIMessage;
}
}
function onMIDIMessage(message) {
// data comes in the form [command/channel, note, velocity]
data = message.data;
// Opacity change for screen. The cross fader values are [176, 8, {0-127}]
if ( (data[0] === 176) && (data[1] === 8) ) {
// this value will change as the fader is moved
var opacity = data[2]/127;
screenTwo.style.opacity = opacity;
}
}
The final code was slightly more complicated than this, as I decided to switch the two screens based on the frequencies of the sound that was playing, and use the cross fader to depict the frequency threshold value. This meant they flickered in and out of each other, rather than just faded. There’s a very rough-and-ready first version of the software on GitHub.
Phew, Great! Now we need to get all this to the streets!
Step three: Portable kit
Did you notice how I mentioned a case to carry it all around in? I wanted the case to be morphable, so I could use the equipment from it too, a sort of bag-to-usherette-tray-type affair. Well, I had an unused laptop bag…
I strengthened it with some MDF, so when I opened the bag it would hold like a tray where the laptop and MIDI controller would sit. The projector was Velcroed to the external pocket of the bag, so when it was a tray it would project from underneath. I added two durable straps, one for my shoulders and one round my waist, both attached to the bag itself. There was a lot of cutting and trimming. As it was a laptop bag it was pretty thick to start and sewing was tricky. However, I only broke one sewing machine needle; I’ve been known to break more working with leather, so I figured I was doing well. By the way, you can actually buy usherette trays, but I just couldn’t resist hacking my own :)
Step four: Take to the streets
First, make sure everything is charged – everything – a lot! The laptop has to power both the MIDI controller and the projector, and although I have a mobile phone battery booster pack, that’ll only charge the projector should it run out. I estimated I could get a good hour of visual artistry before I needed to worry, though.
I had a couple of ideas about time of day and location. Here in the UK at this time of year, it gets dark around half past four, so I could easily head out in a city around 5pm and it would be dark enough for the projections to be seen pretty well. I chose Bristol, around the waterfront, as there were some interesting locations to try it out in. The best was Millennium Square: busy but not crowded and plenty of surfaces to try projecting on to.
My first time out with the portable audio/visual pack (PAVP as it will now be named) was brilliant. I played music and projected visuals, like a one-woman band of A/V!
You might be thinking what the point of this was, besides, of course, it being a bit of fun. Well, this project got me to look at canvas and SVG more closely. The Web MIDI API was really interesting; MIDI as a data format has some great practical uses. I think without our side projects we may not have all these wonderful uses for our everyday code. Not only do they remind us coding can, and should, be fun, they also help us learn and grow as makers.
My favourite part? When I was projecting into a water feature in Millennium Square. For those who are familiar, you’ll know it’s like a wall of water so it produced a superb effect. I drew quite a crowd and a kid came to stand next to me and all I could hear him say with enthusiasm was, ‘Oh wow! That’s so cool!’
Yes… yes, kid, it was cool. Making things with code is cool.
Massive thanks to the lovely Drew McLellan for his incredibly well-directed photography, and also Simon Johnson who took a great hand in perfecting the kit while it was attached. |
2015 |
Ruth John |
ruthjohn |
2015-12-06T00:00:00+00:00 |
https://24ways.org/2015/bringing-your-code-to-the-streets/ |
code |
| 191 |
CSS Animations |
Friend: You should learn how to write CSS!
Me: …
Friend: CSS; Cascading Style Sheets. If you’re serious about web design, that’s the next thing you should learn.
Me: What’s wrong with <font> tags?
That was 8 years ago. Thanks to the hard work of Jeffrey, Andy, Andy, Cameron, Colly, Dan and many others, learning how to decently markup a website and write lightweight stylesheets was surprisingly easy. They made it so easy even a complete idiot (OH HAI) was able to quickly master it.
And then… nothing. For a long time, it seemed like there wasn’t happening anything in the land of CSS, time stood still. Once you knew the basics, there wasn’t anything new to keep up with. It looked like a great band split, but people just kept re-releasing their music in various “Best Of!” or “Remastered!” albums.
Fast forward a couple of years to late 2006. On the official WebKit blog Surfin’ Safari, there’s an article about something called CSS animations. Great new stuff to play with, but only supported by nightly builds (read: very, very beta) of WebKit. In the following months, they release other goodies, like CSS gradients, CSS reflections, CSS masks, and even more CSS animation sexiness. Whoa, looks like the band got back together, found their second youth, and went into overdrive! The problem was that if you wanted to listen to their new albums, you had to own some kind of new high-tech player no one on earth (besides some early adopters) owned.
Back in the time machine. It is now late 2009, close to Christmas. Things have changed. Browsers supporting these new toys are widely available left and right. Even non-techies are using these advanced browsers to surf the web on a daily basis!
Epic win? Almost, but at least this gives us enough reason to start learning how we could use all this new CSS voodoo. On Monday, Natalie Downe showed you a good tutorial on Going Nuts with CSS Transitions. Today, I’m taking it one step further…
Howto: A basic spinner
No matter how fast internet tubes or servers are, we’ll always need spinners to indicate something’s happening behind the scenes. Up until now, people would go to some site, pick one of the available templates, customize their foreground and background colors, and download a beautiful GIF image.
There are some downsides to this though:
It’s only _semi_-transparent: If you change your mind and pick a slightly different background color, you need to go back to the site, set all the parameters again, and replace your current image. There isn’t even a way to pick an image or gradient as background.
Limited number of frames, probable to keep the file-size as small as possible (don’t forget this thing needs to be loaded before whatever process is finished in the background), and you don’t have that 24 frames per second smoothness.
This is just too fucking easy. As a front-end code geek, there must be a “cooler” way to do this!
What do we need to make a spinner with CSS animations? One image, and one element on our webpage we can hook on to. Yes, that’s it. I created a simple transparent PNG that looks it might be a spinner, and for the element on the page, I wrote this piece of genius HTML:
<p id="spinner">Please wait while we do what we do best.</p>
Looks semantic enough to me! Here’s the basic HTML I’m using to position the element in the center of the screen, and make the text inside it disappear:
#spinner {
position: absolute;
top: 50%;
left: 50%;
margin: -100px 0 0 -100px;
height: 200px;
width: 200px;
text-indent: 250px;
white-space: nowrap;
overflow: hidden;
}
Cool, but now we don’t see anything. Let’s pull rabbit number one out of the hat: -webkit-mask-image (accompanied by the previously mentioned transparent PNG image):
#spinner {
...
-webkit-mask-image: url(../img/spinner.png);
}
By now you should be feeling like a magician already. Oh, wait, we still have a blank screen, looks like we left something in the hat (tip: not rabbit droppings):
#spinner {
...
-webkit-mask-image: url(../img/spinner.png);
background-color: #000;
}
Nice! What we’ve done right here is telling the element to clip onto the PNG. It’s a lot like clipping layers in Photoshop. So, spinners, they move, right? Into the hat again, and look what we pull out this time: CSS animations!
#spinner {
...
-webkit-mask-image: url(../img/spinner.png);
background-color: #000;
-webkit-animation-name: spinnerRotate;
-webkit-animation-duration: 2s;
-webkit-animation-iteration-count: infinite;
-webkit-animation-timing-function: linear;
}
Some explanation:
-webkit-animation-name: Name of the animation we’ll be defining later.
-webkit-animation-duration: The timespan of the animation.
-webkit-animation-iteration-count: Repeat once, a defined number of times or infinitely?
-webkit-animation-timing-function: Linear is the one you’ll be using mostly. Other options are ease-in, ease-out, ease-in-out…
Let’s define spinnerRotate:
@-webkit-keyframes spinnerRotate {
from {
-webkit-transform:rotate(0deg);
}
to {
-webkit-transform:rotate(360deg);
}
}
En Anglais: Rotate #spinner starting at 0 degrees, ending at 360 degrees, over a timespan of 2 seconds, at a constant speed, and keep repeating this animation forever.
That’s it! See it in action on the demo page.
Note: these examples only work when you’re using a WebKit-based browser like Safari, Mobile Safari or Google Chrome. I’m confident though that Mozilla and Opera will try their very best catching up with all this new CSS goodness soon.
When looking at this example, you see the possibilities are endless. Another advantage is you can change the look of it entirely by only changing a couple of lines of CSS, instead of re-creating and re-downloading the image from some website smelling like web 2.0 gone bad. I made another demo that shows how great it is to be able to change background and foreground colors (even on the fly!).
So there you have it, a smoothly animated, fully transparent and completely customizable spinner. Cool? I think so. (Ladies?)
But you can do a lot more with CSS animations than just create pretty spinners. Since I was fooling around with it anyway, I decided to test how far you can push this, space is the final limit, right?
Conclusion
CSS has never been more exciting than it is right now. I’m even prepared to say CSS is “cool” again, both for the more experienced front-end developers as for the new designers discovering CSS every day now.
But…
Remember when Javascript became popular? Remember when Flash became popular? Every time we’re been given new toys, some people aren’t ashamed to use it in a way you can barely call constructive. I’m thinking of Geocities websites, loaded with glowing blocks of text, moving images, bad color usage… In the wise words of Stan Lee: With great power there must also come great responsibility! A sprinkle of CSS animations is better than a bucket load. Apply with care. |
2009 |
Tim Van Damme |
timvandamme |
2009-12-15T00:00:00+00:00 |
https://24ways.org/2009/css-animations/ |
code |
| 332 |
CSS Layout Starting Points |
I build a lot of CSS layouts, some incredibly simple, others that cause sleepless nights and remind me of the torturous puzzle books that were given to me at Christmas by aunties concerned for my education. However, most of the time these layouts fit quite comfortably into one of a very few standard formats. For example:
Liquid, multiple column with no footer
Liquid, multiple column with footer
Fixed width, centred
Rather than starting out with blank CSS and (X)HTML documents every time you need to build a layout, you can fairly quickly create a bunch of layout starting points, that will give you a solid basis for creating the rest of the design and mean that you don’t have to remember how a three column layout with a footer is best achieved every time you come across one!
These starting points can be really basic, in fact that’s exactly what you want as the final design, the fonts, the colours and so on will be different every time. It’s just the main sections we want to be able to quickly get into place. For example, here is a basic starting point CSS and XHTML document for a fixed width, centred layout with a footer.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Fixed Width and Centred starting point document</title>
<link rel="stylesheet" type="text/css" href="fixed-width-centred.css" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<div id="wrapper">
<div id="side">
<div class="inner">
<p>Sidebar content here</p>
</div>
</div>
<div id="content">
<div class="inner">
<p>Your main content goes here.</p>
</div>
</div>
<div id="footer">
<div class="inner">
<p>Ho Ho Ho!</p>
</div>
</div>
</div>
</body>
</html>
body {
text-align: center;
min-width: 740px;
padding: 0;
margin: 0;
}
#wrapper {
text-align: left;
width: 740px;
margin-left: auto;
margin-right: auto;
padding: 0;
}
#content {
margin: 0 200px 0 0;
}
#content .inner {
padding-top: 1px;
margin: 0 10px 10px 10px;
}
#side {
float: right;
width: 180px;
margin: 0;
}
#side .inner {
padding-top: 1px;
margin: 0 10px 10px 10px;
}
#footer {
margin-top: 10px;
clear: both;
}
#footer .inner {
margin: 10px;
}
9 times out of 10, after figuring out exactly what main elements I have in a layout, I can quickly grab the ‘one I prepared earlier’, mark-up the relevant sections within the ready-made divs, and from that point on, I only need to worry about the contents of those different areas. The actual layout is tried and tested, one that I know works well in different browsers and that is unlikely to throw me any nasty surprises later on. In addition, considering how the layout is going to work first prevents the problem of developing a layout, then realising you need to put a footer on it, and needing to redevelop the layout as the method you have chosen won’t work well with a footer.
While enjoying your mince pies and mulled wine during the ‘quiet time’ between Christmas and New Year, why not create some starting point layouts of your own? The css-discuss Wiki, CSS layouts section is a great place to find examples that you can try out and find your favourite method of creating the various layout types. |
2005 |
Rachel Andrew |
rachelandrew |
2005-12-04T00:00:00+00:00 |
https://24ways.org/2005/css-layout-starting-points/ |
code |
| 305 |
CSS Writing Modes |
Since you may not have a lot of time, I’m going to start at the end, with the dessert.
You can use a little-known, yet important and powerful CSS property to make text run vertically. Like this.
Or instead of running text vertically, you can layout a set of icons or interface buttons in this way. Or, of course, with anything on your page.
The CSS I’ve applied makes the browser rethink the orientation of the world, and flow the layout of this element at a 90° angle to “normal”. Check out the live demo, highlight the headline, and see how the cursor is now sideways.
See the Pen Writing Mode Demo — Headline by Jen Simmons (@jensimmons) on CodePen.
The code for accomplishing this is pretty simple.
h1 {
writing-mode: vertical-rl;
}
That’s all it takes to switch the writing mode from the web’s default horizontal top-to-bottom mode to a vertical right-to-left mode. If you apply such code to the html element, the entire page is switched, affecting the scroll direction, too.
In my example above, I’m telling the browser that only the h1 will be in this vertical-rl mode, while the rest of my page stays in the default of horizontal-tb.
So now the dessert course is over. Let me serve up this whole meal, and explain the the CSS Writing Mode Specification.
Why learn about writing modes?
There are three reasons I’m teaching writing modes to everyone—including western audiences—and explaining the whole system, instead of quickly showing you a simple trick.
We live in a big, diverse world, and learning about other languages is fascinating. Many of you lay out pages in languages like Chinese, Japanese and Korean. Or you might be inspired to in the future.
Using writing-mode to turn bits sideways is cool. This CSS can be used in all kinds of creative ways, even if you are working only in English.
Most importantly, I’ve found understanding Writing Modes incredibly helpful when understanding Flexbox and CSS Grid. Before I learned Writing Mode, I felt like there was still a big hole in my knowledge, something I just didn’t get about why Grid and Flexbox work the way they do. Once I wrapped my head around Writing Modes, Grid and Flexbox got a lot easier. Suddenly the Alignment properties, align-* and justify-*, made sense.
Whether you know about it or not, the writing mode is the first building block of every layout we create. You can do what we’ve been doing for 25 years – and leave your page set to the default left-to-right direction, horizontal top-to-bottom writing mode. Or you can enter a world of new possibilities where content flows in other directions.
CSS properties
I’m going to focus on the CSS writing-mode property in this article. It has five possible options:
writing-mode: horizontal-tb;
writing-mode: vertical-rl;
writing-mode: vertical-lr;
writing-mode: sideways-rl;
writing-mode: sideways-lr;
The CSS Writing Modes Specification is designed to support a wide range of written languages in all our human and linguistic complexity. Which—spoiler alert—is pretty insanely complex. The global evolution of written languages has been anything but simple.
So I’ve got to start with explaining some basic concepts of web page layout and writing systems. Then I can show you what these CSS properties do.
Inline Direction, Block Direction, and Character Direction
In the world of the web, there’s a concept of ‘block’ and ‘inline’ layout. If you’ve ever written display: block or display: inline, you’ve leaned on these concepts.
In the default writing mode, blocks stack vertically starting at the top of the page and working their way down. Think of how a bunch of block-levels elements stack—like a bunch of a paragraphs—that’s the block direction.
Inline is how each line of text flows. The default on the web is from left to right, in horizontal lines. Imagine this text that you are reading right now, being typed out one character at a time on a typewriter. That’s the inline direction.
The character direction is which way the characters point. If you type a capital “A” for instance, on which side is the top of the letter? Different languages can point in different directions. Most languages have their characters pointing towards the top of the page, but not all.
Put all three together, and you start to see how they work as a system.
The default settings for the web work like this.
Now that we know what block, inline, and character directions mean, let’s see how they are used in different writing systems from around the world.
The four writing systems of CSS Writing Modes
The CSS Writing Modes Specification handles all the use cases for four major writing systems; Latin, Arabic, Han and Mongolian.
Latin-based systems
One writing system dominates the world more than any other, reportedly covering about 70% of the world’s population.
The text is horizontal, running from left to right, or LTR. The block direction runs from top to bottom.
It’s called the Latin-based system because it includes all languages that use the Latin alphabet, including English, Spanish, German, French, and many others. But there are many non-Latin-alphabet languages that also use this system, including Greek, Cyrillic (Russian, Ukrainian, Bulgarian, Serbian, etc.), and Brahmic scripts (Devanagari, Thai, Tibetan), and many more.
You don’t need to do anything in your CSS to trigger this mode. This is the default.
Best practices, however, dictate that you declare in your opening <html> element which language and which direction (LTR or RTL) you are using. This website, for instance, uses <html lang='en-gb' dir='ltr'> to let the browser know this content is published in Great Britian’s version of English, in a left to right direction.
Arabic-based systems
Arabic, Hebrew and a few other languages run the inline direction from right to left. This is commonly known as RTL.
Note that the inline direction still runs horizontally. The block direction runs from top to bottom. And the characters are upright.
It’s not just the flow of text that runs from right to left, but everything about the layout of the website. The upper right-hand corner is the starting position. Important things are on the right. The eyes travel from right to left. So, typically RTL websites use layouts that are just like LTR websites, only flipped.
On websites that support both LTR and RTL, like the United Nations’ site at un.org, the two layouts are mirror images of each other.
For many web developers, our experiences with internationalization have focused solely on supporting Arabic and Hebrew script.
CSS layout hacks for internationalization & RTL
To prepare an LTR project to support RTL, developers have had to create all sorts of hacks. For example, the Drupal community started a convention of marking every margin-left and -right, every padding-left and -right, every float: left and float: right with the comment /* LTR */. Then later developers could search for each instance of that exact comment, and create stylesheets to override each left with right, and vice versa. It’s a tedious and error prone way to work. CSS itself needed a better way to let web developers write their layout code once, and easily switch language directions with a single command.
Our new CSS layout system does exactly that. Flexbox, Grid and Alignment use start and end instead of left and right. This lets us define everything in relationship to the writing system, and switch directions easily. By writing justify-content: flex-start, justify-items: end, and eventually margin-inline-start: 1rem we have code that doesn’t need to be changed.
This is a much better way to work. I know it can be confusing to think through start and end as replacements for left and right. But it’s better for any multiligual project, and it’s better for the web as a whole.
Sadly, I’ve seen CSS preprocessor tools that claim to “fix” the new CSS layout system by getting rid of start and end and bringing back left and right. They want you to use their tool, write justify-content: left, and feel self-righteous. It seems some folks think the new way of working is broken and should be discarded. It was created, however, to fulfill real needs. And to reflect a global internet. As Bruce Lawson says, WWW stands for the World Wide Web, not the Wealthy Western Web. Please don’t try to convince the industry that there’s something wrong with no longer being biased towards western culture. Instead, spread the word about why this new system is here.
Spend a bit of time drilling the concept of inline and block into your head, and getting used to start and end. It will be second nature soon enough.
I’ve also seen CSS preprocessors that let us use this new way of thinking today, even as all the parts aren’t fully supported by browsers yet. Some tools let you write text-align: start instead of text-align: left, and let the preprocessor handle things for you. That is terrific, in my opinion. A great use of the power of a preprocessor to help us switch over now.
But let’s get back to RTL.
How to declare your direction
You don’t want to use CSS to tell the browser to switch from an LTR language to RTL. You want to do this in your HTML. That way the browser has the information it needs to display the document even if the CSS doesn’t load.
This is accomplished mainly on the html element. You should also declare your main language. As I mentioned above, the 24 ways website is using <html lang='en-gb' dir='ltr'> to declare the LTR direction and the use of British English. The UN Arabic website uses <html lang='ar' dir='rtl'>to declare the site as an Arabic site, using a RTL layout.
Things get more complicated when you’ve got a page with a mix of languages. But I’m not going to get into all of that, since this article is focused on CSS and layouts, not explaining everything about internationalization.
Let me just leave direction here by noting that much of the heavy work of laying out the characters which make up each word is handled by Unicode. If you are interested in learning more about LTR, RTL and bidirectional text, watch this video: Introduction to Bidirectional Text, a presentation by Elika Etemad.
Meanwhile, let’s get back to CSS.
The writing mode CSS for Latin-based and Arabic-based systems
For both of these systems—Latin-based and Arabic-based, whether LTR or RTL—the same CSS property applies for specifying the writing mode: writing-mode: horizontal-tb. That’s because in both systems, the inline text flow is horizontal, while the block direction is top-to-bottom. This is expressed as horizontal-tb.
horizontal-tb is the default writing mode for the web, so you don’t need to specify it unless you are overriding something else higher up in the cascade. You can just imagine that every site you’ve ever built came with:
html {
writing-mode: horizontal-tb;
}
Now let’s turn our attention to the vertical writing systems.
Han-based systems
This is where things start to get interesting.
Han-based writing systems include CJK languages, Chinese, Japanese, Korean and others. There are two options for laying out a page, and sometimes both are used at the same time.
Much of CJK text is laid out like Latin-based languages, with a horizontal top-to-bottom block direction, and a left-to-right inline direction. This is the more modern way to doing things, started in the 20th century in many places, and further pushed into domination by the computer and later the web.
The CSS to do this bit of the layouts is the same as above:
section {
writing-mode: horizontal-tb;
}
Or, you know, do nothing, and get that result as a default.
Alternatively Han-based languages can be laid out in a vertical writing mode, where the inline direction runs vertically, and the block direction goes from right to left.
See both options in this diagram:
Note that the horizontal text flows from left to right, while the vertical text flows from right to left. Wild, eh?
This Japanese issue of Vogue magazine is using a mix of writing modes. The cover opens on the left spine, opposite of what an English magazine does.
This page mixes English and Japanese, and typesets the Japanese text in both horizontal and vertical modes. Under the title “Richard Stark” in red, you can see a passage that’s horizontal-tb and LTR, while the longer passage of text at the bottom of the page is typeset vertical-rl. The red enlarged cap marks the beginning of that passage. The long headline above the vertical text is typeset LTR, horizontal-tb.
The details of how to set the default of the whole page will depend on your use case. But each element, each headline, each section, each article can be marked to flow the opposite of the default however you’d like.
For example, perhaps you leave the default as horizontal-tb, and specify your vertical elements like this:
div.articletext {
writing-mode: vertical-rl;
}
Or alternatively you could change the default for the page to a vertical orientation, and then set specific elements to horizontal-tb, like this:
html {
writing-mode: vertical-rl;
}
h2, .photocaptions, section {
writing-mode: horizontal-tb;
}
If your page has a sideways scroll, then the writing mode will determine whether the page loads with upper left corner as the starting point, and scroll to the right (horizontal-tb as we are used to), or if the page loads with the upper right corner as the starting point, scrolling to the left to display overflow. Here’s an example of that change in scrolling direction, in a CSS Writing Mode demo by Chen Hui Jing. Check out her demo — you can switch from horizontal to vertical writing modes with a checkbox and see the difference.
Mongolian-based systems
Now, hopefully so far all of this kind of makes sense. It might be a bit more complicated than expected, but it’s not so hard. Well, enter the Mongolian-based systems.
Mongolian is also a vertical script language. Text runs vertically down the page. Just like Han-based systems. There are two major differences. First, the block direction runs the other way. In Mongolian, block-level elements stack from left to right.
Here’s a drawing of how Wikipedia would look in Mongolian if it were laid out correctly.
Perhaps the Mongolian version of Wikipedia will be redone with this layout.
Now you might think, that doesn’t look so weird. Tilt your head to the left, and it’s very familiar. The block direction starts on the left side of the screen and goes to the right. The inline direction starts on the top of the page and moves to the bottom (similar to RTL text, just turned 90° counter-clockwise). But here comes the other huge difference. The character direction is “upside down”. The top of the Mongolian characters are not pointing to the left, towards the start edge of the block direction. They point to the right. Like this:
Now you might be tempted to ignore all this. Perhaps you don’t expect to be typesetting Mongolian content anytime soon. But here’s why this is important for everyone — the way Mongolian works defines the results writing-mode: vertical-lr. And it means we cannot use vertical-lr for typesetting content in other languages in the way we might otherwise expect.
If we took what we know about vertical-rl and guessed how vertical-lr works, we might imagine this:
But that’s wrong. Here’s how they actually compare:
See the unexpected situation? In both writing-mode: vertical-rl and writing-mode: vertical-lr latin text is rotated clockwise. Neither writing mode let’s us rotate text counter-clockwise.
If you are typesetting Mongolian content, apply this CSS in the same way you would apply writing-mode to Han-based writing systems. To the whole page on the html element, or to specific pages of the page like this:
section {
writing-mode: vertical-lr;
}
Now, if you are using writing-mode for a graphic design effect on a language that is otherwise typesets horizontally, I don’t think writing-mode: vertical-lr is useful. If the text wraps onto two lines, it stacks in a very unexpected way. So I’ve sort of obliterated it from my toolkit. I find myself using writing-mode: vertical-rl a lot. And never using -lr. Hm.
Writing modes for graphic design
So how do we use writing-mode to turn English headlines sideways? We could rely on transform: rotate()
Here are two examples, one for each direction. (By the way, each of these demos use CSS Grid for their overall layout, so be sure to test them in a browser that supports CSS Grid, like Firefox Nightly.)
In this demo 4A, the text is rotated clockwise using this code:
h1 {
writing-mode: vertical-rl;
}
In this demo 4B, the text is rotated counter-clockwise using this code:
h1 {
writing-mode: vertical-rl;
transform: rotate(180deg);
text-align: right;
}
I use vertical-rl to rotate the text so that it takes up the proper amount of space in the overall flow of the layout. Then I rotate it 180° to spin it around to the other direction. And then I use text-align: right to get it to rise up to the top of it’s container. This feels like a hack, but it’s a hack that works.
Now what I would like to do instead is use another CSS value that was designed for this use case — one of the two other options for writing mode.
If I could, I would lay out example 4A with:
h1 {
writing-mode: sideways-rl;
}
And layout example 4B with:
h1 {
writing-mode: sideways-lr;
}
The problem is that these two values are only supported in Firefox. None of the other browsers recognize sideways-*. Which means we can’t really use it yet.
In general, the writing-mode property is very well supported across browsers. So I’ll use writing-mode: vertical-rl for now, with the transform: rotate(180deg); hack to fake the other direction.
There’s much more to what we can do with the CSS designed to support multiple languages, but I’m going to stop with this intermediate introduction.
If you do want a bit more of a taste, look at this example that adds text-orientation: upright; to the mix — turning the individual letters of the latin font to be upright instead of sideways.
It’s this demo 4C, with this CSS applied:
h1 {
writing-mode: vertical-rl;
text-orientation: upright;
text-transform: uppercase;
letter-spacing: -25px;
}
You can check out all my Writing Modes demos at labs.jensimmons.com/#writing-modes.
I’ll leave you with this last demo. One that applies a vertical writing mode to the sub headlines of a long article. I like how small details like this can really bring a fresh feeling to the content.
See the Pen Writing Mode Demo — Article Subheadlines by Jen Simmons (@jensimmons) on CodePen. |
2016 |
Jen Simmons |
jensimmons |
2016-12-23T00:00:00+00:00 |
https://24ways.org/2016/css-writing-modes/ |
code |
| 283 |
CSS3 Patterns, Explained |
Many of you have probably seen my CSS3 patterns gallery. It became very popular throughout the year and it showed many web developers how powerful CSS3 gradients really are. But how many really understand how these patterns are created? The biggest benefit of CSS-generated backgrounds is that they can be modified directly within the style sheet. This benefit is void if we are just copying and pasting CSS code we don’t understand. We may as well use a data URI instead.
Important note
In all the examples that follow, I’ll be using gradients without a vendor prefix, for readability and brevity. However, you should keep in mind that in reality you need to use all the vendor prefixes (-moz-, -ms-, -o-, -webkit-) as no browser currently implements them without a prefix. Alternatively, you could use -prefix-free and have the current vendor prefix prepended at runtime, only when needed.
The syntax described here is the one that browsers currently implement. The specification has since changed, but no browser implements the changes yet. If you are interested in what is coming, I suggest you take a look at the dev version of the spec.
If you are not yet familiar with CSS gradients, you can read these excellent tutorials by John Allsopp and return here later, as in the rest of the article I assume you already know the CSS gradient basics:
CSS3 Linear Gradients
CSS3 Radial Gradients
The main idea
I’m sure most of you can imagine the background this code generates:
background: linear-gradient(left, white 20%, #8b0 80%);
It’s a simple gradient from one color to another that looks like this:
See this example live
As you probably know, in this case the first 20% of the container’s width is solid white and the last 20% is solid green. The other 60% is a smooth gradient between these colors. Let’s try moving these color stops closer to each other:
background: linear-gradient(left, white 30%, #8b0 70%);
See this example live
background: linear-gradient(left, white 40%, #8b0 60%);
See this example live
background: linear-gradient(left, white 50%, #8b0 50%);
See this example live
Notice how the gradient keeps shrinking and the solid color areas expanding, until there is no gradient any more in the last example. We can even adjust the position of these two color stops to control where each color abruptly changes into another:
background: linear-gradient(left, white 30%, #8b0 30%);
See this example live
background: linear-gradient(left, white 90%, #8b0 90%);
See this example live
What you need to take away from these examples is that when two color stops are at the same position, there is no gradient, only solid colors. Even without going any further, this trick is useful for a number of different use cases like faux columns or the effect I wanted to achieve in my homepage or the -prefix-free page where the background is only shown on one side and hidden on the other:
Combining with background-size
We can do wonders, however, if we combine this with the CSS3 background-size property:
background: linear-gradient(left, white 50%, #8b0 50%);
background-size: 100px 100px;
See this example live
And there it is. We just created the simplest of patterns: (vertical) stripes. We can remove the first parameter (left) or replace it with top and we’ll get horizontal stripes. However, let’s face it: Horizontal and vertical stripes are kinda boring. Most stripey backgrounds we see on the web are diagonal. So, let’s try doing that.
Our first attempt would be to change the angle of the gradient to something like 45deg. However, this results in an ugly pattern like this:
See this example live
Before reading on, think for a second: why didn’t this produce the desired result? Can you figure it out?
The reason is that the gradient angle rotates the gradient inside each tile, not the tiled background as a whole. However, didn’t we have the same problem the first time we tried to create diagonal stripes with an image? And then we learned that every stripe has to be included twice, like so:
So, let’s try to create that effect with CSS gradients. It’s essentially what we tried before, but with more color stops:
background: linear-gradient(45deg, white 25%,
#8b0 25%, #8b0 50%,
white 50%, white 75%,
#8b0 75%);
background-size:100px 100px;
See this example live
And there we have our stripes! An easy way to remember the order of the percentages and colors it is that you always have two of the same in succession, except the first and last color.
Note: Firefox for Mac also needs an additional 100% color stop at the end of any pattern with more than two stops, like so: ..., white 75%, #8b0 75%, #8b0). The bug was reported in February 2011 and you can vote for it and track its progress at Bugzilla.
Unfortunately, this is essentially a hack and we will realize that if we try to change the gradient angle to 60deg:
See this example live
Not that maintainable after all, eh? Luckily, CSS3 offers us another way of declaring such backgrounds, which not only helps this case but also results in much more concise code:
background: repeating-linear-gradient(60deg, white, white 35px, #8b0 35px, #8b0 70px);
See this example live
In this case, however, the size has to be declared in the color stop positions and not through background-size, since the gradient is supposed to cover the entire container. You might notice that the declared size is different from the one specified the previous way. This is because the size of the stripes is measured differently: in the first example we specify the dimensions of the tile itself; in the second, the width of the stripes (35px), which is measured diagonally.
Multiple backgrounds
Using only one gradient you can create stripes and that’s about it. There are a few more patterns you can create with just one gradient (linear or radial) but they are more or less boring and ugly. Almost every pattern in my gallery contains a number of different backgrounds. For example, let’s create a polka dot pattern:
background: radial-gradient(circle, white 10%, transparent 10%),
radial-gradient(circle, white 10%, black 10%) 50px 50px;
background-size:100px 100px;
See this example live
Notice that the two gradients are almost the same image, but positioned differently to create the polka dot effect. The only difference between them is that the first (topmost) gradient has transparent instead of black. If it didn’t have transparent regions, it would effectively be the same as having a single gradient, as the topmost gradient would obscure everything beneath it.
There is an issue with this background. Can you spot it?
This background will be fine for browsers that support CSS gradients but, for browsers that don’t, it will be transparent as the whole declaration is ignored. We have two ways to provide a fallback, each for different use cases. We have to either declare another background before the gradient, like so:
background: black;
background: radial-gradient(circle, white 10%, transparent 10%),
radial-gradient(circle, white 10%, black 10%) 50px 50px;
background-size:100px 100px;
or declare each background property separately:
background-color: black;
background-image: radial-gradient(circle, white 10%, transparent 10%),
radial-gradient(circle, white 10%, transparent 10%);
background-size:100px 100px;
background-position: 0 0, 50px 50px;
The vigilant among you will have noticed another change we made to our code in the last example: we altered the second gradient to have transparent regions as well. This way background-color serves a dual purpose: it sets both the fallback color and the background color of the polka dot pattern, so that we can change it with just one edit. Always strive to make code that can be modified with the least number of edits. You might think that it will never be changed in that way but, almost always, given enough time, you’ll be proved wrong.
We can apply the exact same technique with linear gradients, in order to create checkerboard patterns out of right triangles:
background-color: white;
background-image: linear-gradient(45deg, black 25%, transparent 25%, transparent 75%, black 75%),
linear-gradient(45deg, black 25%, transparent 25%, transparent 75%, black 75%);
background-size:100px 100px;
background-position: 0 0, 50px 50px;
See this example live
Using the right units
Don’t use pixels for the sizes without any thought. In some cases, ems make much more sense. For example, when you want to make a lined paper background, you want the lines to actually follow the text. If you use pixels, you have to change the size every time you change font-size. If you set the background-size in ems, it will naturally follow the text and you will only have to update it if you change line-height.
Is it possible?
The shapes that can be achieved with only one gradient are:
stripes
right triangles
circles and ellipses
semicircles and other shapes formed from slicing ellipses horizontally or vertically
You can combine several of them to create squares and rectangles (two right triangles put together), rhombi and other parallelograms (four right triangles), curves formed from parts of ellipses, and other shapes.
Just because you can doesn’t mean you should
Technically, anything can be crafted with these techniques. However, not every pattern is suitable for it. The main advantages of this technique are:
no extra HTTP requests
short code
human-readable code (unlike data URIs) that can be changed without even leaving the CSS file.
Complex patterns that require a large number of gradients are probably better left to SVG or bitmap images, since they negate almost every advantage of this technique:
they are not shorter
they are not really comprehensible – changing them requires much more effort than using an image editor
They still save an HTTP request, but so does a data URI.
I have included some very complex patterns in my gallery, because even though I think they shouldn’t be used in production (except under very exceptional conditions), understanding how they work and coding them helps somebody understand the technology in much more depth.
Another rule of thumb is that if your pattern needs shapes to obscure parts of other shapes, like in the star pattern or the yin yang pattern, then you probably shouldn’t use it. In these patterns, changing the background color requires you to also change the color of these shapes, making edits very tedious.
If a certain pattern is not practicable with a reasonable amount of CSS, that doesn’t mean you should resort to bitmap images. SVG is a very good alternative and is supported by all modern browsers.
Browser support
CSS gradients are supported by Firefox 3.6+, Chrome 10+, Safari 5.1+ and Opera 11.60+ (linear gradients since Opera 11.10). Support is also coming in Internet Explorer when IE10 is released. You can get gradients in older WebKit versions (including most mobile browsers) by using the proprietary -webkit-gradient(), if you really need them.
Epilogue
I hope you find these techniques useful for your own designs. If you come up with a pattern that’s very different from the ones already included, especially if it demonstrates a cool new technique, feel free to send a pull request to the github repo of the patterns gallery. Also, I’m always fascinated to see my techniques put in practice, so if you made something cool and used CSS patterns, I’d love to know about it!
Happy holidays! |
2011 |
Lea Verou |
leaverou |
2011-12-16T00:00:00+00:00 |
https://24ways.org/2011/css3-patterns-explained/ |
code |
| 223 |
Calculating Color Contrast |
Some websites and services allow you to customize your profile by uploading pictures, changing the background color or other aspects of the design. As a customer, this personalization turns a web app into your little nest where you store your data. As a designer, letting your customers have free rein over the layout and design is a scary prospect. So what happens to all the stock text and images that are designed to work on nice white backgrounds? Even the Mac only lets you choose between two colors for the OS, blue or graphite! Opening up the ability to customize your site’s color scheme can be a recipe for disaster unless you are flexible and understand how to find maximum color contrasts.
In this article I will walk you through two simple equations to determine if you should be using white or black text depending on the color of the background. The equations are both easy to implement and produce similar results. It isn’t a matter of which is better, but more the fact that you are using one at all! That way, even with the craziest of Geocities color schemes that your customers choose, at least your text will still be readable.
Let’s have a look at a range of various possible colors. Maybe these are pre-made color schemes, corporate colors, or plucked from an image.
Now that we have these potential background colors and their hex values, we need to find out whether the corresponding text should be in white or black, based on which has a higher contrast, therefore affording the best readability. This can be done at runtime with JavaScript or in the back-end before the HTML is served up.
There are two functions I want to compare. The first, I call ’50%’. It takes the hex value and compares it to the value halfway between pure black and pure white. If the hex value is less than half, meaning it is on the darker side of the spectrum, it returns white as the text color. If the result is greater than half, it’s on the lighter side of the spectrum and returns black as the text value.
In PHP:
function getContrast50($hexcolor){
return (hexdec($hexcolor) > 0xffffff/2) ? 'black':'white';
}
In JavaScript:
function getContrast50(hexcolor){
return (parseInt(hexcolor, 16) > 0xffffff/2) ? 'black':'white';
}
It doesn’t get much simpler than that! The function converts the six-character hex color into an integer and compares that to one half the integer value of pure white. The function is easy to remember, but is naive when it comes to understanding how we perceive parts of the spectrum. Different wavelengths have greater or lesser impact on the contrast.
The second equation is called ‘YIQ’ because it converts the RGB color space into YIQ, which takes into account the different impacts of its constituent parts. Again, the equation returns white or black and it’s also very easy to implement.
In PHP:
function getContrastYIQ($hexcolor){
$r = hexdec(substr($hexcolor,0,2));
$g = hexdec(substr($hexcolor,2,2));
$b = hexdec(substr($hexcolor,4,2));
$yiq = (($r*299)+($g*587)+($b*114))/1000;
return ($yiq >= 128) ? 'black' : 'white';
}
In JavaScript:
function getContrastYIQ(hexcolor){
var r = parseInt(hexcolor.substr(0,2),16);
var g = parseInt(hexcolor.substr(2,2),16);
var b = parseInt(hexcolor.substr(4,2),16);
var yiq = ((r*299)+(g*587)+(b*114))/1000;
return (yiq >= 128) ? 'black' : 'white';
}
You’ll notice first that we have broken down the hex value into separate RGB values. This is important because each of these channels is scaled in accordance to its visual impact. Once everything is scaled and normalized, it will be in a range between zero and 255. Much like the previous ’50%’ function, we now need to check if the input is above or below halfway. Depending on where that value is, we’ll return the corresponding highest contrasting color.
That’s it: two simple contrast equations which work really well to determine the best readability.
If you are interested in learning more, the W3C has a few documents about color contrast and how to determine if there is enough contrast between any two colors. This is important for accessibility to make sure there is enough contrast between your text and link colors and the background.
There is also a great article by Kevin Hale on Particletree about his experience with choosing light or dark themes. To round it out, Jonathan Snook created a color contrast picker which allows you to play with RGB sliders to get values for YIQ, contrast and others. That way you can quickly fiddle with the knobs to find the right balance.
Comparing results
Let’s revisit our color schemes and see which text color is recommended for maximum contrast based on these two equations.
If we use the simple ’50%’ contrast function, we can see that it recommends black against all the colors except the dark green and purple on the second row. In general, the equation feels the colors are light and that black is a better choice for the text.
The more complex ‘YIQ’ function, with its weighted colors, has slightly different suggestions. White text is still recommended for the very dark colors, but there are some surprises. The red and pink values show white text rather than black. This equation takes into account the weight of the red value and determines that the hue is dark enough for white text to show the most contrast.
As you can see, the two contrast algorithms agree most of the time. There are some instances where they conflict, but overall you can use the equation that you prefer. I don’t think it is a major issue if some edge-case colors get one contrast over another, they are still very readable.
Now let’s look at some common colors and then see how the two functions compare. You can quickly see that they do pretty well across the whole spectrum.
In the first few shades of grey, the white and black contrasts make sense, but as we test other colors in the spectrum, we do get some unexpected deviation. Pure red #FF0000 has a flip-flop. This is due to how the ‘YIQ’ function weights the RGB parts. While you might have a personal preference for one style over another, both are justifiable.
In this second round of colors, we go deeper into the spectrum, off the beaten track. Again, most of the time the contrasting algorithms are in sync, but every once in a while they disagree. You can select which you prefer, neither of which is unreadable.
Conclusion
Contrast in color is important, especially if you cede all control and take a hands-off approach to the design. It is important to select smart defaults by making the contrast between colors as high as possible. This makes it easier for your customers to read, increases accessibility and is generally just easier on the eyes.
Sure, there are plenty of other equations out there to determine contrast; what is most important is that you pick one and implement it into your system.
So, go ahead and experiment with color in your design. You now know how easy it is to guarantee that your text will be the most readable in any circumstance. |
2010 |
Brian Suda |
briansuda |
2010-12-24T00:00:00+00:00 |
https://24ways.org/2010/calculating-color-contrast/ |
code |
| 157 |
Capturing Caps Lock |
One of the more annoying aspects of having to remember passwords (along with having to remember loads of them) is that if you’ve got Caps Lock turned on accidentally when you type one in, it won’t work, and you won’t know why. Most desktop computers alert you in some way if you’re trying to enter your password to log on and you’ve enabled Caps Lock; there’s no reason why the web can’t do the same. What we want is a warning – maybe the user wants Caps Lock on, because maybe their password is in capitals – rather than something that interrupts what they’re doing. Something subtle.
But that doesn’t answer the question of how to do it. Sadly, there’s no way of actually detecting whether Caps Lock is on directly. However, there’s a simple work-around; if the user presses a key, and it’s a capital letter, and they don’t have the Shift key depressed, why then they must have Caps Lock on! Simple.
DOM scripting allows your code to be notified when a key is pressed in an element; when the key is pressed, you get the ASCII code for that key. Capital letters, A to Z, have ASCII codes 65 to 90. So, the code would look something like:
on a key press
if the ASCII code for the key is between 65 and 90 *and* if shift is pressed
warn the user that they have Caps Lock on, but let them carry on
end if
end keypress
The actual JavaScript for this is more complicated, because both event handling and keypress information differ across browsers. Your event handling functions are passed an event object, except in Internet Explorer where you use the global event object; the event object has a which parameter containing the ASCII code for the key pressed, except in Internet Explorer where the event object has a keyCode parameter; some browsers store whether the shift key is pressed in a shiftKey parameter and some in a modifiers parameter. All this boils down to code that looks something like this:
keypress: function(e) {
var ev = e ? e : window.event;
if (!ev) {
return;
}
var targ = ev.target ? ev.target : ev.srcElement;
// get key pressed
var which = -1;
if (ev.which) {
which = ev.which;
} else if (ev.keyCode) {
which = ev.keyCode;
}
// get shift status
var shift_status = false;
if (ev.shiftKey) {
shift_status = ev.shiftKey;
} else if (ev.modifiers) {
shift_status = !!(ev.modifiers & 4);
}
// At this point, you have the ASCII code in “which”,
// and shift_status is true if the shift key is pressed
}
Then it’s just a check to see if the ASCII code is between 65 and 90 and the shift key is pressed. (You also need to do the same work if the ASCII code is between 97 (a) and 122 (z) and the shift key is not pressed, because shifted letters are lower-case if Caps Lock is on.)
if (((which >= 65 && which <= 90) && !shift_status) ||
((which >= 97 && which <= 122) && shift_status)) {
// uppercase, no shift key
/* SHOW THE WARNING HERE */
} else {
/* HIDE THE WARNING HERE */
}
The warning can be implemented in many different ways: highlight the password field that the user is typing into, show a tooltip, display text next to the field. For simplicity, this code shows the warning as a previously created image, with appropriate alt text. Showing the warning means creating a new <img> tag with DOM scripting, dropping it into the page, and positioning it so that it’s next to the appropriate field. The image looks like this:
You know the position of the field the user is typing into (from its offsetTop and offsetLeft properties) and how wide it is (from its offsetWidth properties), so use createElement to make the new img element, and then absolutely position it with style properties so that it appears in the appropriate place (near to the text field).
The image is a transparent PNG with an alpha channel, so that the drop shadow appears nicely over whatever else is on the page. Because Internet Explorer version 6 and below doesn’t handle transparent PNGs correctly, you need to use the AlphaImageLoader technique to make the image appear correctly.
newimage = document.createElement('img');
newimage.src = "http://farm3.static.flickr.com/2145/2067574980_3ddd405905_o_d.png";
newimage.style.position = "absolute";
newimage.style.top = (targ.offsetTop - 73) + "px";
newimage.style.left = (targ.offsetLeft + targ.offsetWidth - 5) + "px";
newimage.style.zIndex = "999";
newimage.setAttribute("alt", "Warning: Caps Lock is on");
if (newimage.runtimeStyle) {
// PNG transparency for IE
newimage.runtimeStyle.filter += "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='http://farm3.static.flickr.com/2145/2067574980_3ddd405905_o_d.png',sizingMethod='scale')";
}
document.body.appendChild(newimage);
Note that the alt text on the image is also correctly set. Next, all these parts need to be pulled together. On page load, identify all the password fields on the page, and attach a keypress handler to each. (This only needs to be done for password fields because the user can see if Caps Lock is on in ordinary text fields.)
var inps = document.getElementsByTagName("input");
for (var i=0, l=inps.length; i
The “create an image” code from above should only be run if the image is not already showing, so instead of creating a newimage object, create the image and attach it to the password field so that it can be checked for later (and not shown if it’s already showing). For safety, all the code should be wrapped up in its own object, so that its functions don’t collide with anyone else’s functions. So, create a single object called capslock and make all the functions be named methods of the object:
var capslock = {
...
keypress: function(e) {
}
...
}
Also, the “create an image” code is saved into its own named function, show_warning(), and the converse “remove the image” code into hide_warning(). This has the advantage that developers can include the JavaScript library that has been written here, but override what actually happens with their own code, using something like:
<script src="jscapslock.js" type="text/javascript"></script>
<script type="text/javascript">
capslock.show_warning(target) {
// do something different here to warn the user
}
capslock.hide_warning(target) {
// hide the warning that we created in show_warning() above
}
</script>
And that’s all. Simply include the JavaScript library in your pages, override what happens on a warning if that’s more appropriate for what you’re doing, and that’s all you need.
See the script in action. |
2007 |
Stuart Langridge |
stuartlangridge |
2007-12-04T00:00:00+00:00 |
https://24ways.org/2007/capturing-caps-lock/ |
code |
| 204 |
Cascading Web Design with Feature Queries |
Feature queries, also known as the @supports rule, were introduced as an extension to the CSS2 as part of the CSS Conditional Rules Module Level 3, which was first published as a working draft in 2011. It is a conditional group rule that tests if the browser’s user agent supports CSS property:value pairs, and arbitrary conjunctions (and), disjunctions (or), and negations (not) of them.
The motivation behind this feature was to allow authors to write styles using new features when they were supported but degrade gracefully in browsers where they are not. Even though the nature of CSS already allows for graceful degradation, for example, by ignoring unsupported properties or values without disrupting other styles in the stylesheet, sometimes we need a bit more than that.
CSS is ultimately a holistic technology, in that, even though you can use properties in isolation, the full power of CSS shines through when used in combination. This is especially evident when it comes to building web layouts. Having native feature detection in CSS makes it much more convenient to build with cutting-edge CSS for the latest browsers while supporting older browsers at the same time.
Browser support
Opera first implemented feature queries in November 2012, both Chrome and Firefox had it since May 2013. There have been several articles about feature queries written over the years, however, it seems that awareness of its broad support isn’t that well-known. Much of the earlier coverage on feature queries was not written in English, and perhaps that was a limiting factor.
@supports ― CSSのFeature Queries by Masataka Yakura, August 8 2012
Native CSS Feature Detection via the @supports Rule by Chris Mills, December 21 2012
CSS @supports by David Walsh, April 3 2013
Responsive typography with CSS Feature Queries by Aral Balkan, April 9 2013
How to use the @supports rule in your CSS by Lea Verou, January 31 2014
CSS Feature Queries by Amit Tal, June 2 2014
Coming Soon: CSS Feature Queries by Adobe Web Platform Team, August 21 2014
CSS feature queries mittels @supports by Daniel Erlinger, November 27 2014
As of December 2017, all current major browsers and their previous 2 versions support feature queries. Feature queries are also supported on Opera Mini, UC Browser and Samsung Internet. The only browsers that do not support feature queries are Internet Explorer and Blackberry Mobile, but that may be less of an issue than you might think.
Can I Use css-featurequeries? Data on support for the css-featurequeries feature across the major browsers from caniuse.com.
Granted, there is still a significant number of organisations that require support of Internet Explorer. Microsoft still continues to support IE11 for the life-cycle of Windows 7, 8 and 10. They have, however, stopped supporting older versions since January 12, 2016. It is inevitable that there will be organisations that, for some reason or another, make it mandatory to support IE, but as time goes on, this number will continue to shrink.
Jen Simmons wrote an extensive article called Using Feature Queries in CSS which discussed a matrix of potential situations when it comes to the usage of feature queries. The following image is a summary of the aforementioned matrix.
The most tricky situation we have to deal with is the box in the top-left corner, which are “browsers that don’t support feature queries, yet do support the feature in question”. For cases like those, it really depends on the specific CSS feature you want to use and a subsequent evaluation of the pros and cons of not including that feature in spite of the fact the browser (most likely Internet Explorer) supports it.
The basics of feature queries
As with any conditional, feature queries operate on boolean logic, in other words, if the query resolves to true, apply the CSS properties within the block, or else just ignore the entire block altogether. The syntax of a simple feature query is as follows:
.selector {
/* Styles that are supported in old browsers */
}
@supports (property:value) {
.selector {
/* Styles for browsers that support the specified property */
}
}
Note that the parentheses around the property:value pair are mandatory and the rule is invalid without them. Styles that apply to older browsers, i.e. fallback styles, should come first, followed by the newer properties, which are contained within the @supports conditional. Because of the cascade, fallback styles will be overridden by the newer properties in the modern browsers that support them.
main {
background-color: red;
}
@supports (display:grid) {
main {
background-color: green;
}
}
In this example, browsers that support CSS grid will have a main element with a green background colour because the conditional resolves to true, while browsers that do not support grid will have a main element with a red background colour.
The implication of such behaviour means that we can layer on enhanced styles based on the features we want to use and these styles will show up in browsers that support them. But for those that do not, they will get a more basic look that still works anyway. And that will be our approach moving forward.
Boolean operators for feature queries
The and operator allows us to test for support of multiple properties within a single conditional. This would be useful for cases where the desired output requires multiple cutting-edge features to be supported at the same time to work. All the property:value pairs listed in the conditional must resolve to true for the styles within the rule to be applied.
@supports (transform: rotate(45deg)) and
(writing-mode: vertical-rl) {
/* Some CSS styles */
}
The or operator allows us to list multiple property:value pairs in the conditional and as long as one of them resolves to true, the styles within the block will be applied. A relevant use-case would be for properties with vendor-prefixes.
@supports (background: -webkit-gradient(linear, left top, left bottom, from(white), to(black))) or
(background: -o-linear-gradient(top, white, black)) or
(background: linear-gradient(to bottom, white, black)) {
/* Some CSS styles */
}
The not operator negates the resolution of the property:value pair in the conditional, resolving to false when the property is supported and vice versa. This is useful when there are two distinct sets of styles to be applied depending on the support of a specific feature. However, we do need to keep in mind the case where a browser does not support feature queries, and handle the styles for those browsers accordingly.
@supports not (shape-outside: polygon(100% 80%,20% 0,100% 0)) {
/* Some CSS styles */
}
To avoid confusion between and and or, these operators must be explicitly declared as opposed to using commas or spaces. To prevent confusion caused by precedence rules, and, or and not operators cannot be mixed without a layer of parentheses.
This rule is not valid and the styles within the block will be ignored.
@supports (transition-property: background-color) or
(animation-name: fade) and
(transform: scale(1.5)) {
/* Some CSS styles */
}
To make it work, parentheses must be added either around the two properties adjacent to the or or the and operator like so:
@supports ((transition-property: background-color) or
(animation-name: fade)) and
(transform: scale(1.5)) {
/* Some CSS styles */
}
@supports (transition-property: background-color) or
((animation-name: fade) and
(transform: scale(1.5))) {
/* Some CSS styles */
}
The current specification states that whitespace is required after a not and on both sides of an and or or, but this may change in a future version of the specification. It is acceptable to add extra parentheses even when they are not needed, but omission of parentheses is considered invalid.
Cascading web design
I’d like to introduce the concept of cascading web design, an approach made possible with feature queries. Browser update cycles are much shorter these days, so new features and bug fixes are being pushed out a lot more frequently as compared to the early days of the web.
With the maturation of web standards, browser behaviour is less unpredictable than before, but each browser will still have their respective quirks. Chances are, the latest features will not ship across all browsers at the same time. But you know what? That’s perfectly fine. If we accept this as a feature of the web, instead of a bug, we’ve just opened up a lot more web design possibilities.
The following example is a basic, responsive grid layout of items laid out with flexbox, as viewed on IE11.
We can add a block of styles within an @supports rule to apply CSS grid properties for browsers that support them to enhance this layout, like so:
The web is not a static medium. It is dynamic and interactive and we manipulate this medium by writing code to tell the browser what we want it to do. Rather than micromanaging the pixels in our designs, maybe it’s time we cede control of our designs to the browsers that render them. This means being okay with your designs looking different across browsers and devices.
As mentioned earlier, CSS works best when various properties are combined. It’s one of those things whose whole is greater than the sum of its parts. So feature queries, when combined with media queries, allow us to design layouts that are most effective in the environment they have to perform in.
Such an approach requires interpolative thinking, on multiple levels. As web designers and developers, we don’t just think in one fixed dimension, we get to think about how our design will morph on a narrow screen, or on an older browser, in addition to how it will appear on a browser with the latest features.
In the following example, the layout on the left is what IE11 users will see, the one in the middle is what Firefox users will see, because Firefox doesn’t support CSS shapes yet, but once it does, it will then look like the layout on the right, which is what Chrome users see now.
With the release of CSS Grid this year, we’ve hit another milestone in the evolution of the web as a medium. The beauty of the web is its backwards compatibility and generous fault tolerance. Browser features are largely additive, holding onto the good parts and building on top of them, while deprecating the bits that didn’t work well.
Feature queries allow us to progressively enhance our CSS, establishing a basic level of user experience across the widest range of browsers, while building in more advanced functionality for browsers who can use them. And hopefully, this will allow more of us to create designs that truly embrace the nature of the web. |
2017 |
Chen Hui Jing |
chenhuijing |
2017-12-01T00:00:00+00:00 |
https://24ways.org/2017/cascading-web-design/ |
code |
| 313 |
Centered Tabs with CSS |
Doug Bowman’s Sliding Doors is pretty much the de facto way to build tabbed navigation with CSS, and rightfully so – it is, as they say, rockin’ like Dokken. But since it relies heavily on floats for the positioning of its tabs, we’re constrained to either left- or right-hand navigation. But what if we need a bit more flexibility? What if we need to place our navigation in the center?
Styling the li as a floated block does give us a great deal of control over margin, padding, and other presentational styles. However, we should learn to love the inline box – with it, we can create a flexible, centered alternative to floated navigation lists.
Humble Beginnings
Do an extra shot of ‘nog, because you know what’s coming next. That’s right, a simple unordered list:
<div id="navigation">
<ul>
<li><a href="#"><span>Home</span></a></li>
<li><a href="#"><span>About</span></a></li>
<li><a href="#"><span>Our Work</span></a></li>
<li><a href="#"><span>Products</span></a></li>
<li class="last"><a href="#"><span>Contact Us</span></a></li>
</ul>
</div>
If we were wedded to using floats to style our list, we could easily fix the width of our ul, and trick it out with some margin: 0 auto; love to center it accordingly. But this wouldn’t net us much flexibility: if we ever changed the number of navigation items, or if the user increased her browser’s font size, our design could easily break.
Instead of worrying about floats, let’s take the most basic approach possible: let’s turn our list items into inline elements, and simply use text-align to center them within the ul:
#navigation ul, #navigation ul li {
list-style: none;
margin: 0;
padding: 0;
}
#navigation ul {
text-align: center;
}
#navigation ul li {
display: inline;
margin-right: .75em;
}
#navigation ul li.last {
margin-right: 0;
}
Our first step is sexy, no? Well, okay, not really – but it gives us a good starting point. We’ve tamed our list by removing its default styles, set the list items to display: inline, and centered the lot. Adding a background color to the links shows us exactly how the different elements are positioned.
Now the fun stuff.
Inline Elements, Padding, and You
So how do we give our links some dimensions? Well, as the CSS specification tells us, the height property isn’t an option for inline elements such as our anchors. However, what if we add some padding to them?
#navigation li a {
padding: 5px 1em;
}
I just love leading questions. Things are looking good, but something’s amiss: as you can see, the padded anchors seem to be escaping their containing list.
Thankfully, it’s easy to get things back in line. Our anchors have 5 pixels of padding on their top and bottom edges, right? Well, by applying the same vertical padding to the list, our list will finally “contain” its child elements once again.
’Tis the Season for Tabbing
Now, we’re finally able to follow the “Sliding Doors” model, and tack on some graphics:
#navigation ul li a {
background: url("tab-right.gif") no-repeat 100% 0;
color: #06C;
padding: 5px 0;
text-decoration: none;
}
#navigation ul li a span {
background: url("tab-left.gif") no-repeat;
padding: 5px 1em;
}
#navigation ul li a:hover span {
color: #69C;
text-decoration: underline;
}
Finally, our navigation’s looking appropriately sexy. By placing an equal amount of padding on the top and bottom of the ul, our tabs are properly “contained”, and we can subsequently style the links within them.
But what if we want them to bleed over the bottom-most border? Easy: we can simply decrease the bottom padding on the list by one pixel, like so.
A Special Note for Special Browsers
The Mac IE5 users in the audience are likely hopping up and down by now: as they’ve discovered, our centered navigation behaves rather annoyingly in their browser. As Philippe Wittenbergh has reported, Mac IE5 is known to create “phantom links” in a block-level element when text-align is set to any value but the default value of left. Thankfully, Philippe has documented a workaround that gets that [censored] venerable browser to behave. Simply place the following code into your CSS, and the links will be restored to their appropriate width:
/**//*/
#navigation ul li a {
display: inline-block;
white-space: nowrap;
width: 1px;
}
/**/
IE for Windows, however, displays an extra kind of crazy. The padding I’ve placed on my anchors is offsetting the spans that contain the left curve of my tabs; thankfully, these shenanigans are easily straightened out:
/**/
* html #navigation ul li a {
padding: 0;
}
/**/
And with that, we’re finally finished.
All set.
And that’s it. With your centered navigation in hand, you can finally enjoy those holiday toddies and uncomfortable conversations with your skeevy Uncle Eustace. |
2005 |
Ethan Marcotte |
ethanmarcotte |
2005-12-08T00:00:00+00:00 |
https://24ways.org/2005/centered-tabs-with-css/ |
code |
| 214 |
Christmas Gifts for Your Future Self: Testing the Web Platform |
In the last year I became a CSS specification editor, on a mission to revitalise CSS Multi-column layout. This has involved learning about many things, one of which has been the Web Platform Tests project. In this article, I’m going to share what I’ve learned about testing the web platform. I’m also going to explain why I think you might want to get involved too.
Why test?
At one time or another it is likely that you have been frustrated by an issue where you wrote some valid CSS, and one browser did one thing with it and another something else entirely. Experiences like this make many web developers feel that browser vendors don’t work together, or they are actively doing things in a different way to one another to the detriment of those of us who use the platform. You’ll be glad to know that isn’t the case, and that the people who work on browsers want things to be consistent just as much as we do. It turns out however that interoperability, which is the official term for “works in all browsers”, is hard.
Thanks to web-platform-tests, a test from another browser vendor just found genuine bug in our code before we shipped 😻— Brian Birtles (@brianskold) February 10, 2017
In order for W3C Specifications to move on to become W3C Recommendations we need to have interoperable implementations.
6.2.4 Implementation Experience
Implementation experience is required to show that a specification is sufficiently clear, complete, and relevant to market needs, to ensure that independent interoperable implementations of each feature of the specification will be realized. While no exhaustive list of requirements is provided here, when assessing that there is adequate implementation experience the Director will consider (though not be limited to):
is each feature of the current specification implemented, and how is this demonstrated?
are there independent interoperable implementations of the current specification?
are there implementations created by people other than the authors of the specification?
are implementations publicly deployed?
is there implementation experience at all levels of the specification’s ecosystem (authoring, consuming, publishing…)?
are there reports of difficulties or problems with implementation?
https://www.w3.org/2017/Process-20170301/#transition-reqs
We all want interoperability, achieving interoperability is part of the standards process. The next question is, how do we make sure that we get it?
Unimplemented vs uninteroperable implementations
Before looking at how we can try to improve interoperability, I’d like to look at the reasons we don’t always meet that aim. There are a couple of reasons why browser X is not doing the same thing as browser Y.
The first reason is that browser X has not implemented that feature yet. Relatively small teams of people work on browser engines, and their resources are spread as thinly as those of any company. Behind those browsers are business or organisational goals which may not match our desire for a shiny feature to be made available. There are ways in which we as the web community can help gently encourage implementations - by requesting the feature, by using it so it shows up in usage reports, or writing about it to show interest. However, there will always be some degree of lag based on priorities.
A browser not supporting a feature at all, is reasonably easy to deal with these days. We can test for support with Feature Queries, and create sensible fallbacks. What is harder to deal with is when a feature is implemented in different ways by different browsers. In that situation you use the feature, perhaps referring to the specification to ensure that you are writing your CSS correctly. It looks exactly as you expect in one browser and it’s all broken when you test in another.
A frequent cause of this kind of issue is that the specification is not well defined in a particular area or that the specification has changed since one or other browser implemented it. CSS specifications are not developed in a darkened room, then presented to browser vendors to implement as a completed document. It would be nice if it worked like that, however the web platform is a gnarly thing. Before we can be sure that a specification is correct, it needs implementing in order that we can get the interoperable implementations I described earlier. A circular process has to happen. Specifications have to be written, browsers have to implement and find the problems, and then the specification has to be revised.
Many people reading this will be familiar with how flexbox changed three times in browsers, leaving us with a mess of incompatibilities and the need to use at least two versions of the spec. This story was an example of this circular process, in this case the specification was flagged as experimental using vendor prefixes. We had become used to using vendor prefixes in production and early adopters of flexbox were bitten by this. Today, specifications are developed behind experimental flags as we saw with CSS Grid Layout. Yet there has to come a time when implementations ship, and remove those flags, and it may be that knowingly or unknowingly some interop issues slip through.
You will know these interop issues as “browser bugs”, perhaps you have even reported one (thank you!) and none of us want them, so how do we make the platform as robust as possible?
How do we ensure we have interoperability?
If you were working on a large web application, with several people committing code, it would be very easy for one person to make a change that inadvertently broke some part of the application. They might not realise the fact that their change would cause a problem, due to not having a complete understanding of the entire codebase. To prevent this from happening, it is accepted good practice to write tests as well as code. The tests can then be run before the application is deployed.
Unless you start out from the beginning writing tests, and are very good at writing a test for every bit of code, it is likely that some issues do slip through from time to time. When this happens, a good approach is to not only fix the issue but also to write a test that would stop it ever happening again. That way the test suite improves over time and hopefully fewer issues happen.
The web platform is essentially a giant, sprawling application, with a huge range of people working on it in different ways. There is therefore plenty of opportunity for issues to creep in, so it seems like having some way of writing tests and automating those tests on browsers would be a good thing. That, is what the Web Platform Tests project has set out to achieve.
Web Platform Tests
Web Platform Tests is the test suite for the web platform. It is set of tests for all parts of the web platform, which can be run in any browser and the results reported. This article mostly discusses CSS tests, because I work on CSS. You will find that there are tests covering the full platform, and you can look into whichever area you have the most interest and experience in.
If we want to create a test suite for a CSS specification then we need to ensure that every feature of the specification has a related test. If a change is made to the spec, and a test committed that reflects that change, then it should be straightforward to run that test against each browser and see if it passes.
Currently, at the CSS Working Group, specifications that are at Candidate Recommendation Status should commit at test with every normative change to the spec. To explain the terminology, a normative change is one that changes some of the normative text of a specification - text that contains instructions as to how a browser should render a certain thing. A Candidate Recommendation is the status at which the Working Group officially request implementations of the spec, therefore it is reasonable to assume that any change may cause an interoperability issue. It is usually the case that representatives from all browsers will have discussed the change, so anyone who needs to change code will be aware. In this case the test allows them to check that their change passes and matches everyone else. Tests would also highlight the situation where a change to the spec caused an issue in a browser that otherwise wouldn’t be aware if it. Just as a test suite for your web application should alert a person committing code, that their change will cause a problem elsewhere.
Discovering the tests
I’ve found that the more I have understood the effort that goes into interoperability, and the reasons why creating an interoperable web is so hard, running into browser issues has become less frustrating. I have somewhere to go, even if all I can do is log the bug.
If you are even slightly interested in the subject, go have a poke around wpt.fyi. You can explore the various parts of the web platform and see how many tests have been committed. All the the CSS tests are under the directory /css where you will find each specification. Find a specification you are interested in, and look at the tests. Each test has a link to run it in your own browser to see if it passes. This can be useful in itself, if you are battling with an issue and have reduced it down to something specific, you can go and look to see if there is a test covering that and whether it appears to pass or fail in the browser you are battling with. If it turns out that the test fails, it’s probably not you!
A test on the wpt.fyi dashboard
Note: In some tests you will come across mention of a font called Ahem. This is a font designed for testing which contains consistent glyphs. You can read about how to use the font and download it here.
Contributing to Web Platform Tests
You can also become involved with Web Platform Tests. People often ask me how they can become involved in CSS, and I can think of no better way than by writing tests. You need to really understand a feature to accurately come up with a method of testing if it works or not in the different engines. This is not glamorous work, it is however a very useful thing to be involved with.
In addition to helping yourself, and developing the sort of deep knowledge of the platform that enables contribution, you will really help the progress of specifications. There are only a very few people writing specs. If those people also have to write and review all of the tests it slows down their work. If you want a better, more interoperable web, and to massively improve your ability to have nerdy conversations about highly specific things, testing is the place to start.
A local testing setup
Your first stop should be to visit the home of Web Platform Tests. There is some documentation here, which does tend to assume you know about the tests and what you are looking for - having read this article you know as much as I do. To be able to work on tests you will want to:
Clone the WPT repo, this is where all the tests are stored
Install some tools so you can run up a local copy of the tests
The instructions on the Readme in the repo should get you up and running, you can then load your own version of the test suite in a browser at http://web-platform-test:8000, or whichever port you set up.
Running tests locally
Finding things to test
It’s currently not straightforward to locate low-hanging fruit in order to start committing tests. There are some issues flagged up as a good first issue in the GitHub repo, if any of those match your interest and knowledge. Otherwise, a good place to start is where you know of existing interoperability issues. If you are aware of a browser bug, have a look and see if there is a test that addresses it. If not, then a test highlights the interoperability issue, and if it is an issue that you are running into means that you have a nice way to see if it has been fixed!
Talk to people
There is an IRC channel at irc://irc.w3.org:6667/testing, where you will find people who are writing tests as well as people who are working on the test suite framework itself. They have always been very friendly, and are likely to welcome people with a real interest in creating tests.
Gathering information
First you need to read the spec. To be able to create a test you need to know and to understand what the specification says should be happening. As I mentioned, writing tests will improve your knowledge dramatically! In general I find that web developers assume their favourite browser has got it right, this isn’t about right or wrong however, or good browsers versus bad ones. The browser with the incorrect implementation may have had a perfect, as per the spec implementation, until something changed. Do some investigation and work out what the spec says, and which – if any – browser is doing it correctly.
Another good place to look when trying to create a test for an interop issue, is to look at the browser issue trackers. It is quite likely that someone has already logged the issue, and detailed what it is, and even which browsers are as per the spec. This is useful information, as you then have a clue as to which browsers should pass your test. Remember to check version numbers - an issue may well be fixed in a pre-release version of Chrome for example, but not in the public release.
Edge Issue Tracker
Mozilla Issue Tracker
WebKit Issue Tracker
Chromium Issue Tracker
Writing the test
If you’ve ever created a Reduced Test Case to isolate a browser issue, you already have some idea of what we are trying to do with a test. We want to test one thing, in isolation, and to be able to confirm “yes this works as per the spec” or “no, this does not”.
The main two types of test are:
testharness.js tests
reftests
The testharness.js tests use JavaScript to test an assertion, this framework is designed as a way to test Web APIs and as this quickly gets fairly complicated - and I’m a complete beginner myself at writing these - I’ll refer you to the excellent tutorial Using testharness.js.
Many CSS tests will be reftests. A reftest involves getting two pages to lay out in the same way, so that they are visually the same. For example, you can find a reftest for Grid Layout at:https://w3c-test.org/css/css-grid/alignment/grid-gutters-001.html or at http://web-platform.test:8000/css/css-grid/alignment/grid-gutters-001.html if you have run up your own copy of WPT.
<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Grid Layout Test: Support for gap shorthand property of row-gap and column-gap</title>
<link rel="help" href="https://www.w3.org/TR/css-grid-1/#gutters">
<link rel="help" href="https://www.w3.org/TR/css-align-3/#gap-shorthand">
<link rel="match" href="../reference/grid-equal-gutters-ref.html">
<link rel="author" title="Rachel Andrew" href="mailto:me@rachelandrew.co.uk">
<style>
#grid {
display: grid;
width:200px;
gap: 20px;
grid-template-columns: 90px 90px;
grid-template-rows: 90px 90px;
background-color: green;
}
#grid > div {
background-color: silver;
}
</style>
<p>The test passes if it has the same visual effect as reference.</p>
<div id="grid">
<div></div>
<div></div>
<div></div>
<div></div>
</div>
I am testing the new gap property (renamed grid-gap). The reference file can be found by looking for the line:
<link rel="match" href="../reference/grid-equal-gutters-ref.html">
In that file, I am using absolute positioning to mock up the way the file would look if gap is implemented correctly.
<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Grid Layout Reference: a square with a green cross</title>
<link rel="author" title="Rachel Andrew" href="mailto:me@rachelandrew.co.uk" />
<style>
#grid {
width:200px;
height: 200px;
background-color: green;
position: relative;
}
#grid > div {
background-color: silver;
width: 90px;
height: 90px;
position: absolute;
}
#grid :nth-child(1) {
top: 0;
left: 0;
}
#grid :nth-child(2) {
top: 0;
left: 110px;
}
#grid :nth-child(3) {
top: 110px;
left: 0;
}
#grid :nth-child(4) {
top: 110px;
left: 110px;
}
</style>
<div id="grid">
<div></div>
<div></div>
<div></div>
<div></div>
</div>
The tests are compared in an automated way by taking screenshots of the test and reference.
These are relatively simple tests to write, you will find the work is not in writing the test however. The work is really in doing the research, and making sure you understand what is supposed to happen so you can write the test. Which is why, if you really want to get your hands dirty in the web platform, this is a good place to start.
Committing a test
Once you have written a test you can run the lint tool to make sure that everything is tidy. This tool is run automatically after you submit your pull request, and reviewers won’t accept a test with lint errors, so do this locally first to catch anything obvious.
Tests are added as a pull request, once you have your test ready to go you can create a pull request to add it to the repository. Your test will be tested and it will then wait for a review.
You may well then find yourself in a bit of a waiting game, as the test needs to be reviewed. How long that takes will depend on how active work is on that spec. People who are in the OWNERS file for that spec should be notified. You can always ask in IRC to see if someone is available who can look at and potentially merge your test.
Usually the reviewer will have some comments as to how the test can be improved, in the same as the owner of an open source project you submit a PR to might ask you to change some things. Work with them to make your test as good as it can be, the things you learn on the first test you submit will make future ones easier. You can then bask in the glow of knowing you have done something towards the aim of a more interoperable web for all of us.
Christmas gifts for your future self
I have been a web developer for over 20 years. I have no idea what the web platform will look like in 20 more years, but for as long as I’m working on it I’ll keep on trying to make it better. Making the web more interoperable makes it a better place to be a web developer, storing up some Christmas gifts for my future self, while learning new things as I do so.
Resources
I rounded up everything I could find on WPT while researching this article. As well as some other links that might be helpful for you. These links are below. Happy testing!
Web Platform Tests
Using testharness.js
IRC Channel irc://irc.w3.org:6667/testing
Edge Issue Tracker
Mozilla Issue Tracker
WebKit Issue Tracker
Chromium Issue Tracker
Reducing an Issue - guide to created a reduced test case
Effectively Using Web Platform Tests: Slides and Video
An excellent walkthrough from Lyza Gardner on her working on tests for the HTML specification - Moving Targets: a case study on testing web standards.
Improving interop with web-platform-tests: Slides and Video |
2017 |
Rachel Andrew |
rachelandrew |
2017-12-10T00:00:00+00:00 |
https://24ways.org/2017/testing-the-web-platform/ |
code |
| 147 |
Christmas Is In The AIR |
That’s right, Christmas is coming up fast and there’s plenty of things to do. Get the tree and lights up, get the turkey, buy presents and who know what else. And what about Santa? He’s got a list. I’m pretty sure he’s checking it twice.
Sure, we could use an existing list making web site or even a desktop widget. But we’re geeks! What’s the fun in that? Let’s build our own to-do list application and do it with Adobe AIR!
What’s Adobe AIR?
Adobe AIR, formerly codenamed Apollo, is a runtime environment that runs on both Windows and OSX (with Linux support to follow). This runtime environment lets you build desktop applications using Adobe technologies like Flash and Flex. Oh, and HTML. That’s right, you web standards lovin’ maniac. You can build desktop applications that can run cross-platform using the trio of technologies, HTML, CSS and JavaScript.
If you’ve tried developing with AIR before, you’ll need to get re-familiarized with the latest beta release as many things have changed since the last one (such as the API and restrictions within the sandbox.)
To get started
To get started in building an AIR application, you’ll need two basic things:
The AIR runtime. The runtime is needed to run any AIR-based application.
The SDK. The software development kit gives you all the pieces to test your application. Unzip the SDK into any folder you wish.
You’ll also want to get your hands on the JavaScript API documentation which you’ll no doubt find yourself getting into before too long. (You can download it, too.)
Also of interest, some development environments have support for AIR built right in. Aptana doesn’t have support for beta 3 yet but I suspect it’ll be available shortly.
Within the SDK, there are two main tools that we’ll use: one to test the application (ADL) and another to build a distributable package of our application (ADT). I’ll get into this some more when we get to that stage of development.
Building our To-do list application
The first step to building an application within AIR is to create an XML file that defines our default application settings. I call mine application.xml, mostly because Aptana does that by default when creating a new AIR project. It makes sense though and I’ve stuck with it. Included in the templates folder of the SDK is an example XML file that you can use.
The first key part to this after specifying things like the application ID, version, and filename, is to specify what the default content should be within the content tags. Enter in the name of the HTML file you wish to load. Within this HTML file will be our application.
<content>ui.html</content>
Create a new HTML document and name it ui.html and place it in the same directory as the application.xml file. The first thing you’ll want to do is copy over the AIRAliases.js file from the frameworks folder of the SDK and add a link to it within your HTML document.
<script type="text/javascript" src="AIRAliases.js"></script>
The aliases create shorthand links to all of the Flash-based APIs.
Now is probably a good time to explain how to debug your application.
Debugging our application
So, with our XML file created and HTML file started, let’s try testing our ‘application’. We’ll need the ADL application located in BIN folder of the SDK and tell it to run the application.xml file.
/path/to/adl /path/to/application.xml
You can also just drag the XML file onto ADL and it’ll accomplish the same thing. If you just did that and noticed that your blank application didn’t load, you’d be correct. It’s running but isn’t visible. Which at this point means you’ll have to shut down the ADL process. Sorry about that!
Changing the visibility
You have two ways to make your application visible. You can do it automatically by setting the placing true in the visible tag within the application.xml file.
<visible>true</visible>
The other way is to do it programmatically from within your application. You’d want to do it this way if you had other startup tasks to perform before showing the interface. To turn the UI on programmatically, simple set the visible property of nativeWindow to true.
<script type="text/javascript">
nativeWindow.visible = true;
</script>
Sandbox Security
Now that we have an application that we can see when we start it, it’s time to build the to-do list application. In doing so, you’d probably think that using a JavaScript library is a really good idea — and it can be but there are some limitations within AIR that have to be considered.
An HTML document, by default, runs within the application sandbox. You have full access to the AIR APIs but once the onload event of the window has fired, you’ll have a limited ability to make use of eval and other dynamic script injection approaches. This limits the ability of external sources from gaining access to everything the AIR API offers, such as database and local file system access. You’ll still be able to make use of eval for evaluating JSON responses, which is probably the most important if you wish to consume JSON-based services.
If you wish to create a greater wall of security between AIR and your HTML document loading in external resources, you can create a child sandbox. We won’t need to worry about it for our application so I won’t go any further into it but definitely keep this in mind.
Finally, our application
Getting tired of all this preamble? Let’s actually build our to-do list application. I’ll use jQuery because it’s small and should suit our needs nicely. Let’s begin with some structure:
<body>
<input type="text" id="text" value="">
<input type="button" id="add" value="Add">
<ul id="list"></ul>
</body>
Now we need to wire up that button to actually add a new item to our to-do list.
<script type="text/javascript">
$(document).ready(function(){
// make sure the application is visible
nativeWindow.visible = true;
$('#add').click(function(){
var t = $('#text').val();
if(t)
{
// use DOM methods to create the new list item
var li = document.createElement('li');
// the extra space at the end creates a buffer between the text
// and the delete link we're about to add
li.appendChild(document.createTextNode(t + ' '));
// create the delete link
var del = document.createElement('a');
// this makes it a true link. I feel dirty doing this.
del.setAttribute('href', '#');
del.addEventListener('click', function(evt){
this.parentNode.parentNode.removeChild(this.parentNode);
});
del.appendChild(document.createTextNode('[del]'));
li.appendChild(del);
// append everything to the list
$('#list').append(li);
//reset the text box
$('#text').val('');
}
})
});
</script>
And just like that, we’ve got a to-do list! That’s it! Just never close your application and you’ll remember everything. Okay, that’s not very practical. You need to have some way of storing your to-do items until the next time you open up the application.
Storing Data
You’ve essentially got 4 different ways that you can store data:
Using the local database. AIR comes with SQLLite built in. That means you can create tables and insert, update and select data from that database just like on a web server.
Using the file system. You can also create files on the local machine. You have access to a few folders on the local system such as the documents folder and the desktop.
Using EcryptedLocalStore. I like using the EcryptedLocalStore because it allows you to easily save key/value pairs and have that information encrypted. All this within just a couple lines of code.
Sending the data to a remote API. Our to-do list could sync up with Remember the Milk, for example.
To demonstrate some persistence, we’ll use the file system to store our files. In addition, we’ll let the user specify where the file should be saved. This way, we can create multiple to-do lists, keeping them separate and organized.
The application is now broken down into 4 basic tasks:
Load data from the file system.
Perform any interface bindings.
Manage creating and deleting items from the list.
Save any changes to the list back to the file system.
Loading in data from the file system
When the application starts up, we’ll prompt the user to select a file or specify a new to-do list. Within AIR, there are 3 main file objects: File, FileMode, and FileStream. File handles file and path names, FileMode is used as a parameter for the FileStream to specify whether the file should be read-only or for write access. The FileStream object handles all the read/write activity.
The File object has a number of shortcuts to default paths like the documents folder, the desktop, or even the application store. In this case, we’ll specify the documents folder as the default location and then use the browseForSave method to prompt the user to specify a new or existing file. If the user specifies an existing file, they’ll be asked whether they want to overwrite it.
var store = air.File.documentsDirectory;
var fileStream = new air.FileStream();
store.browseForSave("Choose To-do List");
Then we add an event listener for when the user has selected a file. When the file is selected, we check to see if the file exists and if it does, read in the contents, splitting the file on new lines and creating our list items within the interface.
store.addEventListener(air.Event.SELECT, fileSelected);
function fileSelected()
{
air.trace(store.nativePath);
// load in any stored data
var byteData = new air.ByteArray();
if(store.exists)
{
fileStream.open(store, air.FileMode.READ);
fileStream.readBytes(byteData, 0, store.size);
fileStream.close();
if(byteData.length > 0)
{
var s = byteData.readUTFBytes(byteData.length);
oldlist = s.split(“\r\n”);
// create todolist items
for(var i=0; i < oldlist.length; i++)
{
createItem(oldlist[i], (new Date()).getTime() + i );
}
}
}
}
Perform Interface Bindings
This is similar to before where we set the click event on the Add button but we’ve moved the code to save the list into a separate function.
$('#add').click(function(){
var t = $('#text').val();
if(t){
// create an ID using the time
createItem(t, (new Date()).getTime() );
}
})
Manage creating and deleting items from the list
The list management is now in its own function, similar to before but with some extra information to identify list items and with calls to save our list after each change.
function createItem(t, id)
{
if(t.length == 0) return;
// add it to the todo list
todolist[id] = t;
// use DOM methods to create the new list item
var li = document.createElement('li');
// the extra space at the end creates a buffer between the text
// and the delete link we're about to add
li.appendChild(document.createTextNode(t + ' '));
// create the delete link
var del = document.createElement('a');
// this makes it a true link. I feel dirty doing this.
del.setAttribute('href', '#');
del.addEventListener('click', function(evt){
var id = this.id.substr(1);
delete todolist[id]; // remove the item from the list
this.parentNode.parentNode.removeChild(this.parentNode);
saveList();
});
del.appendChild(document.createTextNode('[del]'));
del.id = 'd' + id;
li.appendChild(del);
// append everything to the list
$('#list').append(li);
//reset the text box
$('#text').val('');
saveList();
}
Save changes to the file system
Any time a change is made to the list, we update the file. The file will always reflect the current state of the list and we’ll never have to click a save button. It just iterates through the list, adding a new line to each one.
function saveList(){
if(store.isDirectory) return;
var packet = '';
for(var i in todolist)
{
packet += todolist[i] + '\r\n';
}
var bytes = new air.ByteArray();
bytes.writeUTFBytes(packet);
fileStream.open(store, air.FileMode.WRITE);
fileStream.writeBytes(bytes, 0, bytes.length);
fileStream.close();
}
One important thing to mention here is that we check if the store is a directory first. The reason we do this goes back to our browseForSave call. If the user cancels the dialog without selecting a file first, then the store points to the documentsDirectory that we set it to initially. Since we haven’t specified a file, there’s no place to save the list.
Hopefully by this point, you’ve been thinking of some cool ways to pimp out your list. Now we need to package this up so that we can let other people use it, too.
Creating a Package
Now that we’ve created our application, we need to package it up so that we can distribute it. This is a two step process. The first step is to create a code signing certificate (or you can pay for one from Thawte which will help authenticate you as an AIR application developer).
To create a self-signed certificate, run the following command. This will create a PFX file that you’ll use to sign your application.
adt -certificate -cn todo24ways 1024-RSA todo24ways.pfx mypassword
After you’ve done that, you’ll need to create the package with the certificate
adt -package -storetype pkcs12 -keystore todo24ways.pfx todo24ways.air application.xml .
The important part to mention here is the period at the end of the command. We’re telling it to package up all files in the current directory.
After that, just run the AIR file, which will install your application and run it.
Important things to remember about AIR
When developing an HTML application, the rendering engine is Webkit. You’ll thank your lucky stars that you aren’t struggling with cross-browser issues. (My personal favourites are multiple backgrounds and border radius!)
Be mindful of memory leaks. Things like Ajax calls and event binding can cause applications to slowly leak memory over time. Web pages are normally short lived but desktop applications are often open for hours, if not days, and you may find your little desktop application taking up more memory than anything else on your machine!
The WebKit runtime itself can also be a memory hog, usually taking about 15MB just for itself. If you create multiple HTML windows, it’ll add another 15MB to your memory footprint. Our little to-do list application shouldn’t be much of a concern, though.
The other important thing to remember is that you’re still essentially running within a Flash environment. While you probably won’t notice this working in small applications, the moment you need to move to multiple windows or need to accomplish stuff beyond what HTML and JavaScript can give you, the need to understand some of the Flash-based elements will become more important.
Lastly, the other thing to remember is that HTML links will load within the AIR application. If you want a link to open in the users web browser, you’ll need to capture that event and handle it on your own. The following code takes the HREF from a clicked link and opens it in the default web browser.
air.navigateToURL(new air.URLRequest(this.href));
Only the beginning
Of course, this is only the beginning of what you can do with Adobe AIR. You don’t have the same level of control as building a native desktop application, such as being able to launch other applications, but you do have more control than what you could have within a web application. Check out the Adobe AIR Developer Center for HTML and Ajax for tutorials and other resources.
Now, go forth and create your desktop applications and hopefully you finish all your shopping before Christmas!
Download the example files. |
2007 |
Jonathan Snook |
jonathansnook |
2007-12-19T00:00:00+00:00 |
https://24ways.org/2007/christmas-is-in-the-air/ |
code |
| 192 |
Cleaner Code with CSS3 Selectors |
The parts of CSS3 that seem to grab the most column inches on blogs and in articles are the shiny bits. Rounded corners, text shadow and new ways to achieve CSS layouts are all exciting and bring with them all kinds of possibilities for web design. However what really gets me, as a developer, excited is a bit more mundane.
In this article I’m going to take a look at some of the ways our front and back-end code will be simplified by CSS3, by looking at the ways we achieve certain visual effects now in comparison to how we will achieve them in a glorious, CSS3-supported future. I’m also going to demonstrate how we can use these selectors now with a little help from JavaScript – which can work out very useful if you find yourself in a situation where you can’t change markup that is being output by some server-side code.
The wonder of nth-child
So why does nth-child get me so excited? Here is a really common situation, the designer would like the tables in the application to look like this:
Setting every other table row to a different colour is a common way to enhance readability of long rows. The tried and tested way to implement this is by adding a class to every other row. If you are writing the markup for your table by hand this is a bit of a nuisance, and if you stick a row in the middle you have to change the rows the class is applied to. If your markup is generated by your content management system then you need to get the server-side code to add that class – if you have access to that code.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Striping every other row - using classes</title>
<style type="text/css">
body {
padding: 40px;
margin: 0;
font: 0.9em Arial, Helvetica, sans-serif;
}
table {
border-collapse: collapse;
border: 1px solid #124412;
width: 600px;
}
th {
border: 1px solid #124412;
background-color: #334f33;
color: #fff;
padding: 0.4em;
text-align: left;
}
td {
padding: 0.4em;
}
tr.odd td {
background-color: #86B486;
}
</style>
</head>
<body>
<table>
<tr>
<th>Name</th>
<th>Cards sent</th>
<th>Cards received</th>
<th>Cards written but not sent</th>
</tr>
<tr>
<td>Ann</td>
<td>40</td>
<td>28</td>
<td>4</td>
</tr>
<tr class="odd">
<td>Joe</td>
<td>2</td>
<td>27</td>
<td>29</td>
</tr>
<tr>
<td>Paul</td>
<td>5</td>
<td>35</td>
<td>2</td>
</tr>
<tr class="odd">
<td>Louise</td>
<td>65</td>
<td>65</td>
<td>0</td>
</tr>
</table>
</body>
</html>
View Example 1
This situation is something I deal with on almost every project, and apart from being an extra thing to do, it just isn’t ideal having the server-side code squirt classes into the markup for purely presentational reasons. This is where the nth-child pseudo-class selector comes in. The server-side code creates a valid HTML table for the data, and the CSS then selects the odd rows with the following selector:
tr:nth-child(odd) td {
background-color: #86B486;
}
View Example 2
The odd and even keywords are very handy in this situation – however you can also use a multiplier here. 2n would be equivalent to the keyword ‘odd’ 3n would select every third row and so on.
Browser support
Sadly, nth-child has pretty poor browser support. It is not supported in Internet Explorer 8 and has somewhat buggy support in some other browsers. Firefox 3.5 does have support. In some situations however, you might want to consider using JavaScript to add this support to browsers that don’t have it. This can be very useful if you are dealing with a Content Management System where you have no ability to change the server-side code to add classes into the markup.
I’m going to use jQuery in these examples as it is very simple to use the same CSS selector used in the CSS to target elements with jQuery – however you could use any library or write your own function to do the same job. In the CSS I have added the original class selector to the nth-child selector:
tr:nth-child(odd) td, tr.odd td {
background-color: #86B486;
}
Then I am adding some jQuery to add a class to the markup once the document has loaded – using the very same nth-child selector that works for browsers that support it.
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
$(document).ready(function(){
$("tr:nth-child(odd)").addClass("odd");
});
</script>
View Example 3
We could just add a background colour to the element using jQuery, however I prefer not to mix that information into the JavaScript as if we change the colour on our table rows I would need to remember to change it both in the CSS and in the JavaScript.
Doing something different with the last element
So here’s another thing that we often deal with. You have a list of items all floated left with a right hand margin on each element constrained within a fixed width layout. If each element has the right margin applied the margin on the final element will cause the set to become too wide forcing that last item down to the next row as shown in the below example where I have used a grey border to indicate the fixed width.
Currently we have two ways to deal with this. We can put a negative right margin on the list, the same width as the space between the elements. This means that the extra margin on the final element fills that space and the item doesn’t drop down.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>The last item is different</title>
<style type="text/css">
body {
padding: 40px;
margin: 0;
font: 0.9em Arial, Helvetica, sans-serif;
}
div#wrapper {
width: 740px;
float: left;
border: 5px solid #ccc;
}
ul.gallery {
margin: 0 -10px 0 0;
padding: 0;
list-style: none;
}
ul.gallery li {
float: left;
width: 240px;
margin: 0 10px 10px 0;
}
</style>
</head>
<body>
<div id="wrapper">
<ul class="gallery">
<li><img src="xmas1.jpg" alt="baubles" /></li>
<li><img src="xmas2.jpg" alt="star" /></li>
<li><img src="xmas3.jpg" alt="wreath" /></li>
</ul>
</div>
</body>
</html>
View Example 4
The other solution will be to put a class on the final element and in the CSS remove the margin for this class.
ul.gallery li.last {
margin-right: 0;
}
This second solution may not be easy if the content is generated from server-side code that you don’t have access to change.
It could all be so different. In CSS3 we have marvellously common-sense selectors such as last-child, meaning that we can simply add rules for the last list item.
ul.gallery li:last-child {
margin-right: 0;
}
View Example 5
This removed the margin on the li which is the last-child of the ul with a class of gallery. No messing about sticking classes on the last item, or pushing the width of the item out wit a negative margin.
If this list of items repeated ad infinitum then you could also use nth-child for this task. Creating a rule that makes every 3rd element margin-less.
ul.gallery li:nth-child(3n) {
margin-right: 0;
}
View Example 6
A similar example is where the designer has added borders to the bottom of each element – but the last item does not have a border or is in some other way different. Again, only a class added to the last element will save you here if you cannot rely on using the last-child selector.
Browser support for last-child
The situation for last-child is similar to that of nth-child, in that there is no support in Internet Explorer 8. However, once again it is very simple to replicate the functionality using jQuery. Adding our .last class to the last list item.
$("ul.gallery li:last-child").addClass("last");
We could also use the nth-child selector to add the .last class to every third list item.
$("ul.gallery li:nth-child(3n)").addClass("last");
View Example 7
Fun with forms
Styling forms can be a bit of a trial, made difficult by the fact that any CSS applied to the input element will effect text fields, submit buttons, checkboxes and radio buttons. As developers we are left adding classes to our form fields to differentiate them. In most builds all of my text fields have a simple class of text whereas I wouldn’t dream of adding a class of para to every paragraph element in a document.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Syling form fields</title>
<style type="text/css">
body {
padding: 40px;
margin: 0;
font: 0.9em Arial, Helvetica, sans-serif;
}
form div {
clear: left;
padding: 0 0 0.8em 0;
}
form label {
float: left;
width: 120px;
}
form .text, form textarea {
border:1px solid #333;
padding: 0.2em;
width: 400px;
}
form .button {
border: 1px solid #333;
background-color: #eee;
color: #000;
padding: 0.1em;
}
</style>
</head>
<body>
<h1>Send your Christmas list to Santa</h1>
<form method="post" action="" id="christmas-list">
<div><label for="fName">Name</label>
<input type="text" name="fName" id="fName" class="text" /></div>
<div><label for="fEmail">Email address</label>
<input type="text" name="fEmail" id="fEmail" class="text" /></div>
<div><label for="fList">Your list</label>
<textarea name="fList" id="fList" rows="10" cols="30"></textarea></div>
<div><input type="submit" name="btnSubmit" id="btnSubmit" value="Submit" class="button" ></div>
</form>
</body>
</html>
View Example 8
Attribute selectors provide a way of targeting elements by looking at the attributes of those elements. Unlike the other examples in this article which are CSS3 selectors, the attribute selector is actually a CSS2.1 selector – it just doesn’t get much use because of lack of support in Internet Explorer 6. Using attribute selectors we can write rules for text inputs and form buttons without needing to add any classes to the markup. For example after removing the text and button classes from my text and submit button input elements I can use the following rules to target them:
form input[type="text"] {
border: 1px solid #333;
padding: 0.2em;
width: 400px;
}
form input[type="submit"]{
border: 1px solid #333;
background-color: #eee;
color: #000;
padding: 0.1em;
}
View Example 9
Another problem that I encounter with forms is where I am using CSS to position my labels and form elements by floating the labels. This works fine as long as I want all of my labels to be floated, however sometimes we get a set of radio buttons or a checkbox, and I don’t want the label field to be floated. As you can see in the below example the label for the checkbox is squashed up into the space used for the other labels, yet it makes more sense for the checkbox to display after the text.
I could use a class on this label element however CSS3 lets me to target the label attribute directly by looking at the value of the for attribute.
label[for="fOptIn"] {
float: none;
width: auto;
}
Being able to precisely target attributes in this way is incredibly useful, and once IE6 is no longer an issue this will really help to clean up our markup and save us from having to create all kinds of special cases when generating this markup on the server-side.
Browser support
The news for attribute selectors is actually pretty good with Internet Explorer 7+, Firefox 2+ and all other modern browsers all having support. As I have already mentioned this is a CSS2.1 selector and so we really should expect to be able to use it as we head into 2010! Internet Explorer 7 has slightly buggy support and will fail on the label example shown above however I discovered a workaround in the Sitepoint CSS reference comments. Adding the selector label[htmlFor="fOptIn"] to the correct selector will create a match for IE7.
IE6 does not support these selector but, once again, you can use jQuery to plug the holes in IE6 support. The following jQuery will add the text and button classes to your fields and also add a checks class to the label for the checkbox, which you can use to remove the float and width for this element.
$('form input[type="submit"]').addClass("button");
$('form input[type="text"]').addClass("text");
$('label[for="fOptIn"]').addClass("checks");
View Example 10
The selectors I’ve used in this article are easy to overlook as we do have ways to achieve these things currently. As developers – especially when we have frameworks and existing code that cope with these situations – it is easy to carry on as we always have done.
I think that the time has come to start to clean up our front and backend code and replace our reliance on classes with these more advanced selectors. With the help of a little JavaScript almost all users will still get the full effect and, where we are dealing with purely visual effects, there is definitely a case to be made for not worrying about the very small percentage of people with old browsers and no JavaScript. They will still receive a readable website, it may just be missing some of the finesse offered to the modern browsing experience. |
2009 |
Rachel Andrew |
rachelandrew |
2009-12-20T00:00:00+00:00 |
https://24ways.org/2009/cleaner-code-with-css3-selectors/ |
code |
| 253 |
Clip Paths Know No Bounds |
CSS Shapes are getting a lot of attention as browser support has increased for properties like shape-outside and clip-path. There are a few ways that we can use CSS Shapes, in particular with the clip-path property, that are not necessarily evident at first glance.
The basics of a clip path
Before we dig into specific techniques to expand on clip paths, we should first take a look at a basic shape and clip-path. Clip paths can apply a CSS Shape such as a circle(), ellipse(), inset(), or the flexible polygon() to any element. Everywhere in the element that is not within the bounds of our shape will be visually removed.
Using the polygon shape function, for example, we can create triangles, stars, or other straight-edged shapes as on Bennett Feely’s Clippy. While fixed units like pixels can be used when defining vertices/points (where the sides meet), percentages will give more flexibility to adapt to the element’s dimensions.
See the Pen Clip Path Box by Dan Wilson (@danwilson) on CodePen.
So for an octagon, we can set eight x, y pairs of percentages to define those points. In this case we start 30% into the width of the box for the first x and at the top of the box for the y and go clockwise. The visible area becomes the interior of the shape made by connecting these points with straight lines.
clip-path: polygon(
30% 0%,
70% 0%,
100% 30%,
100% 70%,
70% 100%,
30% 100%,
0% 70%,
0% 30%
);
A shape with less vertices than the eye can see
It’s reasonable to look at the polygon() function and assume that we need to have one pair of x, y coordinates for every point in our shape. However, we gain some flexibility by thinking outside the box — or more specifically when we think outside the range of 0% - 100%.
Our element’s box model will be the ultimate boundary for a clip-path, but we can still define points that exist beyond that natural box for an element.
See the Pen CSS Shapes Know No Bounds by Dan Wilson (@danwilson) on CodePen.
By going beyond the 0% - 100% range we can turn a polygon with three points into a quadrilateral, a pentagon, or a hexagon. In this example the shapes used are all similar triangles defining three points, but due to exceeding the bounds for our element box we visually see one triangle and two pentagons.
Our earlier octagon can similarly be made with only four points.
See the Pen Octagon with four points by Dan Wilson (@danwilson) on CodePen.
Multiple shapes, one clip path
We can lean on this power of going beyond the bounds of our element to also create more than one visual shape with a single polygon().
See the Pen Multiple shapes from one clip-path by Dan Wilson (@danwilson) on CodePen.
Depending on how we lay it out we can make each shape directly, but since we know we can move around in the space beyond the element’s box, we can draw extra lines to help us get where we need to go next as needed.
It can also help us in slicing an element. Combined with CSS Variables, we can work with overlapping elements and clip each one into alternating strips. This example is two elements, each divided into a few rectangles.
See the Pen 24w: Sliced Icon by Dan Wilson (@danwilson) on CodePen.
Different shapes with fill rules
A polygon() is not just a collection of points. There is one more key piece to its puzzle according to the specification — the Fill Rule. The default value we have been using so far is nonzero, and the second option is evenodd. These two values help determine what is considered inside and outside the shape.
See the Pen A Star Multiways by Dan Wilson (@danwilson) on CodePen.
As lines intersect we can get into situations where pieces seemingly on the inside can be considered outside the shape boundary. When using the evenodd fill rule, we can determine if a given point is inside or outside the boundary by drawing a ray from the point in any direction. If the ray crosses an even number of the clip path’s lines, the point is considered outside, and if it crosses an odd number the point is inside.
Order of operations
It is important to note that there are many CSS properties that affect the final composited appearance of an element via CSS Filters, Blend Modes, and more.
These compositing effects are applied in the order:
CSS Filters (e.g. filter: blur(2px))
Clipping (e.g. what this article is about)
Masking (Clipping’s cousin)
Blend Modes (e.g. mix-blend-mode: multiply)
Opacity
This means if we want to have a star shape and blur it, the blur will happen before the clip. And since blurs are most noticeable around the edge of an element box, the effect might be completely lost since we have clipped away the element’s box edges.
See the Pen Order of Filter + Clip by Dan Wilson (@danwilson) on CodePen.
If we want the edges of the star to be blurred, we do have the option to wrap our clipped element in a blurred parent element. The inner element will be rendered first (with its star clip) and then the parent will blur its contents normally.
Revealing content with animation
CSS Shapes can be transitioned and animated, allowing us to animate the visual area of our element without affecting the content within. For example, we can start with visually hidden content (fully clipped) and grow the clip path to reveal the content within. The important caveat for polygon() is that the number of points need to be the same for each keyframe, as well as the fill rule. Otherwise the browser will not have enough information to interpolate the intermediate values.
See the Pen Clip Path Shape Reveal by Dan Wilson (@danwilson) on CodePen.
Don’t keep CSS Shapes in a box
Clip paths give us some interesting new possibilities, especially when we think of them as more than just basic shapes. We may be heavily modifying the visual representation of our elements with clip-path, but the underlying content remains unchanged and accessible which makes this property fairly powerful. |
2018 |
Dan Wilson |
danwilson |
2018-12-20T00:00:00+00:00 |
https://24ways.org/2018/clip-paths-know-no-bounds/ |
code |
| 8 |
Coding Towards Accessibility |
“Can we make it AAA-compliant?” – does this question strike fear into your heart? Maybe for no other reason than because you will soon have to wade through the impenetrable WCAG documentation once again, to find out exactly what AAA-compliant means?
I’m not here to talk about that.
The Web Content Accessibility Guidelines are a comprehensive and peer-reviewed resource which we’re lucky to have at our fingertips. But they are also a pig to read, and they may have contributed to the sense of mystery and dread with which some developers associate the word accessibility.
This Christmas, I want to share with you some thoughts and some practical tips for building accessible interfaces which you can start using today, without having to do a ton of reading or changing your tools and workflow.
But first, let’s clear up a couple of misconceptions.
Dreary, flat experiences
I recently built a front-end framework for the Post Office. This was a great gig for a developer, but when I found out about my client’s stringent accessibility requirements I was concerned that I’d have to scale back what was quite a complex set of visual designs.
Sites like Jakob Neilsen’s old workhorse useit.com and even the pioneering GOV.UK may have to shoulder some of the blame for this. They put a premium on usability and accessibility over visual flourish. (Although, in fairness to Mr Neilsen, his new site nngroup.com is really quite a snazzy affair, comparatively.)
Of course, there are other reasons for these sites’ aesthetics — and it’s not because of the limitations of the form. You can make an accessible site look as glossy or as plain as you want it to look. It’s always our own ingenuity and attention to detail that are going to be the limiting factors.
Synecdoche
We must always guard against the tendency to assume that catering to screen readers means we have the whole accessibility ballgame covered.
There’s so much more to accessibility than assistive technology, as you know. And within the field of assistive technology there are plenty of other devices for us to consider.
Planning to accommodate all these users and devices can be daunting. When I first started working in this field I thought that the breadth of technology was prohibitive. I didn’t even know what a screen reader looked like. (I assumed they were big and heavy, perhaps like an old typewriter, and certainly they would be expensive and difficult to fathom.) This is nonsense, of course. Screen reader emulators are readily available as browser extensions and can be activated in seconds. Chromevox and Fangs are both excellent and you should download one or the other right now.
But the really good news is that you can emulate many other types of assistive technology without downloading a byte. And this is where we move from misconceptions into some (hopefully) useful advice.
The mouse trap
The simplest and most effective way to improve your abilities as a developer of accessible interfaces is to unplug your mouse.
Keyboard operation has its own WCAG chapter, because most users of assistive technology are navigating the web using only their keyboards. You can go some way towards putting yourself into their shoes so easily — just by ditching a peripheral.
Learning this was a lightbulb moment for me. When I build interfaces I am constantly flicking between code and the browser, testing or viewing the changes I have made. Now, instead of checking a new element once, I check it twice: once with my mouse and then again without.
Don’t just :hover
The reality is that when you first start doing this you can find your site becomes unusable straightaway. It’s easy to lose track of which element is in focus as you hit the tab key repeatedly.
One of the easiest changes you can make to your coding practice is to add :focus and :active pseudo-classes to every hover state that you write. I’m still amazed at how many sites fail to provide a decent focus state for links (and despite previous 24 ways authors in 2007 and 2009 writing on this same issue!).
You may find that in some cases it makes sense to have something other than, or in addition to, the hover state on focus, but start with the hover state that your designer has taken the time to provide you with. It’s a tiny change and there is no downside. So instead of this:
.my-cool-link:hover {
background-color: MistyRose ;
}
…try writing this:
.my-cool-link:hover,
.my-cool-link:focus,
.my-cool-link:active {
background-color: MistyRose ;
}
I’ve toyed with the idea of making a Sass mixin to take care of this for me, but I haven’t yet. I worry that people reading my code won’t see that I’m explicitly defining my focus and active states so I take the hit and write my hover rules out longhand.
JavaScript can play, too
This was another revelation for me. Keyboard-only navigation doesn’t necessitate a JavaScript-free experience, and up-to-date screen readers can execute JavaScript. So we’re able to create complex JavaScript-driven interfaces which all users can interact with.
Some of the hard work has already been done for us. First, there are already conventions around keyboard-driven interfaces. Think about the last time you viewed a photo album on Facebook. You can use the arrow keys to switch between photos, and the escape key closes whichever lightbox-y UI thing Facebook is showing its photos in this week. Arrow keys (up/down as well as left/right) for progression through content; Escape to back out of something; Enter or space bar to indicate a positive intention — these are established keyboard conventions which we can apply to our interfaces to improve their accessiblity.
Of course, by doing so we are improving our interfaces in general, giving all users the option to switch between keyboard and mouse actions as and when it suits them.
Second, this guy wants to help you out. Hans Hillen is a developer who has done a great deal of work around accessibility and JavaScript-powered interfaces. Along with The Paciello Group he has created a version of the jQuery UI library which has been fully optimised for keyboard navigation and screen reader use. It’s a fantastic reference which I revisit all the time
I’m not a huge fan of the jQuery UI library. It’s a pain to style and the code is a bit bloated. So I’ve not used this demo as a code resource to copy wholesale. I use it by playing with the various components and seeing how they react to keyboard controls. Each component is also fully marked up with the relevant ARIA roles to improve screen reader announcement where possible (more on this below).
Coding for accessibility promotes good habits
This is a another observation around accessibility and JavaScript. I noticed an improvement in the structure and abstraction of my code when I started adding keyboard controls to my interface elements.
Your code has to become more modular and event-driven, because any number of events could trigger the same interaction. A mouse-click, the Enter key and the space bar could all conceivably trigger the same open function on a collapsed accordion element. (And you want to keep things DRY, don’t you?)
If you aren’t already in the habit of separating out your interface functionality into discrete functions, you will be soon.
var doSomethingCool = function(){
// Do something cool here.
}
// Bind function to a button click - pretty vanilla
$('.myCoolButton').on('click', function(){
doSomethingCool();
return false;
});
// Bind the same function to a range of keypresses
$(document).keyup(function(e){
switch(e.keyCode) {
case 13: // enter
case 32: // spacebar
doSomethingCool();
break;
case 27: // escape
doSomethingElse();
break;
}
});
To be honest, if you’re doing complex UI stuff with JavaScript these days, or if you’ve been building any responsive interfaces which rely on JavaScript, then you are most likely working with an application framework such as Backbone, Angular or Ember, so an abstraced and event-driven application structure will be familar to you. It should be super easy for you to start helping out your keyboard-only users if you aren’t already — just add a few more event bindings into your UI layer!
Manipulating the tab order
So, you’ve adjusted your mindset and now you test every change to your codebase using a keyboard as well as a mouse. You’ve applied all your hover states to :focus and :active so you can see where you’re tabbing on the page, and your interactive components react seamlessly to a mixture of mouse and keyboard commands. Feels good, right?
There’s another level of optimisation to consider: manipulating the tab order. Certain DOM elements are naturally part of the tab order, and others are excluded. Links and input elements are the main elements included in the tab order, and static elements like paragraphs and headings are excluded. What if you want to make a static element ‘tabbable’?
A good example would be in an expandable accordion component. Each section of the accordion should be separated by a heading, and there’s no reason to make that heading into a link simply because it’s interactive.
<div class="accordion-widget">
<h3>Tyrannosaurus</h3>
<p>Tyrannosaurus; meaning "tyrant lizard"...<p>
<h3>Utahraptor</h3>
<p>Utahraptor is a genus of theropod dinosaurs...<p>
<h3>Dromiceiomimus</h3>
<p>Ornithomimus is a genus of ornithomimid dinosaurs...<p>
</div>
Adding the heading elements to the tab order is trivial. We just set their tabindex attribute to zero. You could do this on the server or the client. I prefer to do it with JavaScript as part of the accordion setup and initialisation process.
$('.accordion-widget h3').attr('tabindex', '0');
You can apply this trick in reverse and take elements out of the tab order by setting their tabindex attribute to −1, or change the tab order completely by using other integers. This should be done with great care, if at all. You have to be sure that the markup you remove from the tab order comes out because it genuinely improves the keyboard interaction experience. This is hard to validate without user testing. The danger is that developers will try to sweep complicated parts of the UI under the carpet by taking them out of the tab order. This would be considered a dark pattern — at least on my team!
A farewell ARIA
This is where things can get complex, and I’m no expert on the ARIA specification: I feel like I’ve only dipped my toe into this aspect of coding for accessibility. But, as with WCAG, I’d like to demystify things a little bit to encourage you to look into this area further yourself.
ARIA roles are of most benefit to screen reader users, because they modify and augment screen reader announcements.
Let’s take our dinosaur accordion from the previous section. The markup is semantic, so a screen reader that can’t handle JavaScript will announce all the content within the accordion, no problem.
But modern screen readers can deal with JavaScript, and this means that all the lovely dino information beneath each heading has probably been hidden on document.ready, when the accordion initialised. It might have been hidden using display:none, which prevents a screen reader from announcing content. If that’s as far as you have gone, then you’ve committed an accessibility sin by hiding content from screen readers. Your user will hear a set of headings being announced, with no content in between. It would sound something like this if you were using Chromevox:
> Tyrannosaurus. Heading Three.
> Utahraptor. Heading Three.
> Dromiceiomimus. Heading Three.
We can add some ARIA magic to the markup to improve this, using the tablist role. Start by adding a role of tablist to the widget, and roles of tab and tabpanel to the headings and paragraphs respectively. Set boolean values for aria-selected, aria-hidden and aria-expanded. The markup could end up looking something like this.
<div class="accordion-widget" role="tablist">
<!-- T-rex -->
<h3 role="tab"
tabindex="0"
id="tab-2"
aria-controls="panel-2"
aria-selected="false">Utahraptor</h3>
<p role="tabpanel"
id="panel-2"
aria-labelledby="tab-2"
aria-expanded="false"
aria-hidden="true">Utahraptor is a genus of theropod dinosaurs...</p>
<!-- Dromiceiomimus -->
</div>
Now, if a screen reader user encounters this markup they will hear the following:
> Tyrannosaurus. Tab not selected; one of three.
> Utahraptor. Tab not selected; two of three.
> Dromiceiomimus. Tab not selected; three of three.
You could add arrow key events to help the user browse up and down the tab list items until they find one they like.
Your accordion open() function should update the ARIA boolean values as well as adding whatever classes and animations you have built in as standard. Your users know that unselected tabs are meant to be interacted with, so if a user triggers the open function (say, by hitting Enter or the space bar on the second item) they will hear this:
> Utahraptor. Selected; two of three.
The paragraph element for the expanded item will not be hidden by your CSS, which means it will be announced as normal by the screen reader.
This kind of thing makes so much more sense when you have a working example to play with. Again, I refer you to the fantastic resource that Hans Hillen has put together: this is his take on an accessible accordion, on which much of my example is based.
Conclusion
Getting complex interfaces right for all of your users can be difficult — there’s no point pretending otherwise. And there’s no substitute for user testing with real users who navigate the web using assistive technology every day. This kind of testing can be time-consuming to recruit for and to conduct. On top of this, we now have accessibility on mobile devices to contend with. That’s a huge area in itself, and it’s one which I have not yet had a chance to research properly.
So, there’s lots to learn, and there’s lots to do to get it right. But don’t be disheartened. If you have read this far then I’ll leave you with one final piece of advice: don’t wait.
Don’t wait until you’re building a site which mandates AAA-compliance to try this stuff out. Don’t wait for a client with the will or the budget to conduct the full spectrum of user testing to come along. Unplug your mouse, and start playing with your interfaces in a new way. You’ll be surprised at the things that you learn and the issues you uncover.
And the next time an true accessibility project comes along, you will be way ahead of the game. |
2013 |
Charlie Perrins |
charlieperrins |
2013-12-03T00:00:00+00:00 |
https://24ways.org/2013/coding-towards-accessibility/ |
code |
| 162 |
Conditional Love |
“Browser.” The four-letter word of web design.
I mean, let’s face it: on the good days, when things just work in your target browsers, it’s marvelous. The air smells sweeter, birds’ songs sound more melodious, and both your design and your code are looking sharp.
But on the less-than-good days (which is, frankly, most of them), you’re compelled to tie up all your browsers in a sack, heave them into the nearest river, and start designing all-imagemap websites. We all play favorites, after all: some will swear by Firefox, Opera fans are allegedly legion, and others still will frown upon anything less than the latest WebKit nightly.
Thankfully, we do have an out for those little inconsistencies that crop up when dealing with cross-browser testing: CSS patches.
Spare the Rod, Hack the Browser
Before committing browsercide over some rendering bug, a designer will typically reach for a snippet of CSS fix the faulty browser. Historically referred to as “hacks,” I prefer Dan Cederholm’s more client-friendly alternative, “patches”.
But whatever you call them, CSS patches all work along the same principle: supply the proper property value to the good browsers, while giving higher maintenance other browsers an incorrect value that their frustrating idiosyncratic rendering engine can understand.
Traditionally, this has been done either by exploiting incomplete CSS support:
#content {
height: 1%; // Let's force hasLayout for old versions of IE.
line-height: 1.6;
padding: 1em;
}
html>body #content {
height: auto; // Modern browsers get a proper height value.
}
or by exploiting bugs in their rendering engine to deliver alternate style rules:
#content p {
font-size: .8em;
/* Hide from Mac IE5 \*/
font-size: .9em;
/* End hiding from Mac IE5 */
}
We’ve even used these exploits to serve up whole stylesheets altogether:
@import url("core.css");
@media tty {
i{content:"\";/*" "*/}} @import 'windows-ie5.css'; /*";}
}/* */
The list goes on, and on, and on. For every browser, for every bug, there’s a patch available to fix some rendering bug.
But after some time working with standards-based layouts, I’ve found that CSS patches, as we’ve traditionally used them, become increasingly difficult to maintain. As stylesheets are modified over the course of a site’s lifetime, inline fixes we’ve written may become obsolete, making them difficult to find, update, or prune out of our CSS. A good patch requires a constant gardener to ensure that it adds more than just bloat to a stylesheet, and inline patches can be very hard to weed out of a decently sized CSS file.
Giving the Kids Separate Rooms
Since I joined Airbag Industries earlier this year, every project we’ve worked on has this in the head of its templates:
<link rel="stylesheet" href="-/css/screen/main.css" type="text/css" media="screen, projection" />
<!--[if lt IE 7]>
<link rel="stylesheet" href="-/css/screen/patches/win-ie-old.css" type="text/css" media="screen, projection" />
<![endif]-->
<!--[if gte IE 7]>
<link rel="stylesheet" href="-/css/screen/patches/win-ie7-up.css" type="text/css" media="screen, projection" />
<![endif]-->
The first element is, simply enough, a link element that points to the project’s main CSS file. No patches, no hacks: just pure, modern browser-friendly style rules. Which, nine times out of ten, will net you a design that looks like spilled eggnog in various versions of Internet Explorer.
But don’t reach for the mulled wine quite yet. Immediately after, we’ve got a brace of conditional comments wrapped around two other link elements. These odd-looking comments allow us to selectively serve up additional stylesheets just to the version of IE that needs them. We’ve got one for IE 6 and below:
<!--[if lt IE 7]>
<link rel="stylesheet" href="-/css/screen/patches/win-ie-old.css" type="text/css" media="screen, projection" />
<![endif]-->
And another for IE7 and above:
<!--[if gte IE 7]>
<link rel="stylesheet" href="-/css/screen/patches/win-ie7-up.css" type="text/css" media="screen, projection" />
<![endif]-->
Microsoft’s conditional comments aren’t exactly new, but they can be a valuable alternative to cooking CSS patches directly into a master stylesheet. And though they’re not a W3C-approved markup structure, I think they’re just brilliant because they innovate within the spec: non-IE devices will assume that the comments are just that, and ignore the markup altogether.
This does, of course, mean that there’s a little extra markup in the head of our documents. But this approach can seriously cut down on the unnecessary patches served up to the browsers that don’t need them. Namely, we no longer have to write rules like this in our main stylesheet:
#content {
height: 1%; // Let's force hasLayout for old versions of IE.
line-height: 1.6;
padding: 1em;
}
html>body #content {
height: auto; // Modern browsers get a proper height value.
}
Rather, we can simply write an un-patched rule in our core stylesheet:
#content {
line-height: 1.6;
padding: 1em;
}
And now, our patch for older versions of IE goes in—you guessed it—the stylesheet for older versions of IE:
#content {
height: 1%;
}
The hasLayout patch is applied, our design’s repaired, and—most importantly—the patch is only seen by the browser that needs it. The “good” browsers don’t have to incur any added stylesheet weight from our IE patches, and Internet Explorer gets the conditional love it deserves.
Most importantly, this “compartmentalized” approach to CSS patching makes it much easier for me to patch and maintain the fixes applied to a particular browser. If I need to track down a bug for IE7, I don’t need to scroll through dozens or hundreds of rules in my core stylesheet: instead, I just open the considerably slimmer IE7-specific patch file, make my edits, and move right along.
Even Good Children Misbehave
While IE may occupy the bulk of our debugging time, there’s no denying that other popular, modern browsers will occasionally disagree on how certain bits of CSS should be rendered. But without something as, well, pimp as conditional comments at our disposal, how do we bring the so-called “good browsers” back in line with our design?
Assuming you’re loving the “one patch file per browser” model as much as I do, there’s just one alternative: JavaScript.
function isSaf() {
var isSaf = (document.childNodes && !document.all && !navigator.taintEnabled && !navigator.accentColorName) ? true : false;
return isSaf;
}
function isOp() {
var isOp = (window.opera) ? true : false;
return isOp;
}
Instead of relying on dotcom-era tactics of parsing the browser’s user-agent string, we’re testing here for support for various DOM objects, whose presence or absence we can use to reasonably infer the browser we’re looking at. So running the isOp() function, for example, will test for Opera’s proprietary window.opera object, and thereby accurately tell you if your user’s running Norway’s finest browser.
With scripts such as isOp() and isSaf() in place, you can then reasonably test which browser’s viewing your content, and insert additional link elements as needed.
function loadPatches(dir) {
if (document.getElementsByTagName() && document.createElement()) {
var head = document.getElementsByTagName("head")[0];
if (head) {
var css = new Array();
if (isSaf()) {
css.push("saf.css");
} else if (isOp()) {
css.push("opera.css");
}
if (css.length) {
var link = document.createElement("link");
link.setAttribute("rel", "stylesheet");
link.setAttribute("type", "text/css");
link.setAttribute("media", "screen, projection");
for (var i = 0; i < css.length; i++) {
var tag = link.cloneNode(true);
tag.setAttribute("href", dir + css[0]);
head.appendChild(tag);
}
}
}
}
}
Here, we’re testing the results of isSaf() and isOp(), one after the other. For each function that returns true, then the name of a new stylesheet is added to the oh-so-cleverly named css array. Then, for each entry in css, we create a new link element, point it at our patch file, and insert it into the head of our template.
Fire it up using your favorite onload or DOMContentLoaded function, and you’re good to go.
Scripteat Emptor
At this point, some of the audience’s more conscientious ‘scripters may be preparing to lob figgy pudding at this author’s head. And that’s perfectly understandable; relying on JavaScript to patch CSS chafes a bit against the normally clean separation we have between our pages’ content, presentation, and behavior layers.
And beyond the philosophical concerns, this approach comes with a few technical caveats attached:
Browser detection? So un-133t.
Browser detection is not something I’d typically recommend. Whenever possible, a proper DOM script should check for the support of a given object or method, rather than the device with which your users view your content.
It’s JavaScript, so don’t count on it being available.
According to one site, roughly four percent of Internet users don’t have JavaScript enabled. Your site’s stats might be higher or lower than this number, but still: don’t expect that every member of your audience will see these additional stylesheets, and ensure that your content’s still accessible with JS turned off.
Be a constant gardener.
The sample isSaf() and isOp() functions I’ve written will tell you if the user’s browser is Safari or Opera. As a result, stylesheets written to patch issues in an old browser may break when later releases repair the relevant CSS bugs.
You can, of course, add logic to these simple little scripts to serve up version-specific stylesheets, but that way madness may lie. In any event, test your work vigorously, and keep testing it when new versions of the targeted browsers come out. Make sure that a patch written today doesn’t become a bug tomorrow.
Patching Firefox, Opera, and Safari isn’t something I’ve had to do frequently: still, there have been occasions where the above script’s come in handy. Between conditional comments, careful CSS auditing, and some judicious JavaScript, browser-based bugs can be handled with near-surgical precision.
So pass the ‘nog. It’s patchin’ time. |
2007 |
Ethan Marcotte |
ethanmarcotte |
2007-12-15T00:00:00+00:00 |
https://24ways.org/2007/conditional-love/ |
code |
| 271 |
Creating Custom Font Stacks with Unicode-Range |
Any web designer or front-end developer worth their salt will be familiar with the CSS @font-face rule used for embedding fonts in a web page. We’ve all used it — either directly in our code ourselves, or via one of the web font services like Fontdeck, Typekit or Google Fonts.
If you’re like me, however, you’ll be used to just copying and pasting in a specific incantation of lines designed to get different formats of fonts working in different browsers, and may not have really explored all the capabilities of @font-face properties as defined by the spec.
One such property — the unicode-range descriptor — sounds pretty dull and is easily overlooked. It does, however, have some fairly interesting possibilities when put to use in creative ways.
Unicode-range
The unicode-range descriptor is designed to help when using fonts that don’t have full coverage of the characters used in a page. By adding a unicode-range property to a @font-face rule it is possible to specify the range of characters the font covers.
@font-face {
font-family: BBCBengali;
src: url(fonts/BBCBengali.ttf) format("opentype");
unicode-range: U+00-FF;
}
In this example, the font is to be used for characters in the range of U+00 to U+FF which runs from the unexciting control characters at the start of the Unicode table (symbols like the exclamation mark start at U+21) right through to ÿ at U+FF – the extent of the Basic Latin character range.
By adding multiple @font-face rules for the same family but with different ranges, you can build up complete coverage of the characters your page uses by using different fonts.
When I say that it’s possible to specify the range of characters the font covers, that’s true, but what you’re really doing with the unicode-range property is declaring which characters the font should be used for. This becomes interesting, because instead of merely working with the technical constraints of available characters in a given font, we can start picking and choosing characters to use and selectively mix fonts together.
The best available ampersand
A few years back, Dan Cederholm wrote a post encouraging designers to use the best available ampersand. Dan went on to outline how this can be achieved by wrapping our ampersands in a <span> element with a class applied:
<span class="amp">&</span>
A CSS rule can then be written to select the <span> and apply a different font:
span.amp {
font-family: Baskerville, Palatino, "Book Antiqua", serif;
}
That’s a perfectly serviceable technique, but the drawbacks are clear — you have to add extra markup which is borderline presentational, and you also have to be able to add that markup, which isn’t always possible when working with a CMS.
Perhaps we could do this with unicode-range.
A better best available ampersand
The Unicode code point for an ampersand is U+26, so the ampersand font stack above can be created like so:
@font-face {
font-family: 'Ampersand';
src: local('Baskerville'), local('Palatino'), local('Book Antiqua');
unicode-range: U+26;
}
What we’ve done here is specify a new family called Ampersand and created a font stack for it with the user’s locally installed copies of Baskerville, Palatino or Book Antiqua. We’ve then limited it to a single character range — the ampersand. Of course, those don’t need to be local fonts — they could be web font files, too. If you have a font with a really snazzy ampersand, go for your life.
We can then use that new family in a regular font stack.
h1 {
font-family: Ampersand, Arial, sans-serif;
}
With this in place, any <h1> elements in our page will use the Ampersand family (Baskerville, Palatino or Book Antiqua) for ampersands, and Arial for all other characters. If the user doesn’t have any of the Ampersand family fonts available, the ampersand will fall back to the next item in the font stack, Arial.
You didn’t think it was that easy, did you?
Oh, if only it were so. The problem comes, as ever, with the issue of browser support. The unicode-range property has good support in WebKit browsers (like Safari and Chrome, and the browsers on most popular smartphone platforms) and in recent versions of Internet Explorer. The big stumbling block comes in the form of Firefox, which has no support at all.
If you’re familiar with how CSS works when it comes to unsupported properties, you’ll know that if a browser encounters a property it doesn’t implement, it just skips that declaration and moves on to the next. That works perfectly for things like border-radius — if the browser can’t round off the corners, the declaration is skipped and the user sees square corners instead. Perfect.
Less perfect when it comes to unicode-range, because if no range is specified then the default is that the font is applied for all characters — the whole range. If you’re using a fancy font for flamboyant ampersands, you probably don’t want that applied to all your text if unicode-range isn’t supported. That would be bad. Really bad.
Ensuring good fallbacks
As ever, the trick is to make sure that there’s a sensible fallback in place if a browser doesn’t have support for whatever technology you’re trying to use. This is where being a super nerd about understanding the spec you’re working with really pays off.
We can make use of the rules of the CSS cascade to make sure that if unicode-range isn’t supported we get a sensible fallback font. What would be ideal is if we were able to follow up the @font-face rule with a second rule to override it if Unicode ranges aren’t implemented.
@font-face {
font-family: 'Ampersand';
src: local('Baskerville'), local('Palatino'), local('Book Antiqua');
unicode-range: U+26;
}
@font-face {
font-family: 'Ampersand';
src: local('Arial');
}
In theory, this code should make sense for all browsers. For those that support unicode-range the two rules become cumulative. They specify different ranges for the same family, and in WebKit browsers this has the expected result of using Arial for most characters, but Baskerville and friends for the ampersand. For browsers that don’t have support, the second rule should just supersede the first, setting the font to Arial.
Unfortunately, this code causes current versions of Firefox to freak out and use the first rule, applying Baskerville to the entire range. That’s both unexpected and unfortunate. Bad Firefox. On your rug.
If that doesn’t work, what can we do? Well, we know that if given a unicode-range Firefox will ignore the range and apply the font to all characters. That’s really what we’re trying to achieve. So what if we specified a range for the fallback font, but made sure it only covers some obscure high-value Unicode character we’re never going to use in our page? Then it wouldn’t affect the outcome for browsers that do support ranges.
@font-face {
font-family: 'Ampersand';
src: local('Baskerville'), local('Palatino'), local('Book Antiqua');
unicode-range: U+26;
}
@font-face {
/* Ampersand fallback font */
font-family: 'Ampersand';
src: local('Arial');
unicode-range: U+270C;
}
By specifying a range on the fallback font, Firefox appears to correctly override the first based on the cascade sort order. Browsers that do support ranges take the second rule in addition, and apply Arial for that obscure character we’re not using in any of our pages — U+270C.
So we get our nice ampersands in browsers that support unicode-range and, thanks to our styling of an obscure Unicode character, the font falls back to a perfectly acceptable Arial in browsers that do not offer support. Perfect!
That obscure character, my friends, is what Unicode defines as the VICTORY HAND.
✌
So, how can we use this?
Ampersands are a neat trick, and it works well in browsers that support ranges, but that’s not really the point of all this. Styling ampersands is fun, but they’re only really scratching the surface. Consider more involved examples, such as substituting a different font for numerals, or symbols, or even caps. Things certainly begin to get a bit more interesting.
How do you know what the codes are for different characters? Richard Ishida has a handy online conversion tool available where you can type in the characters and get the Unicode code points out the other end.
Of course, the fact remains that browser support for unicode-range is currently limited, so any application needs to have fallbacks that you’re still happy for a significant proportion of your visitors to see. In some cases, such as dedicated pages for mobile devices in an HTML-based phone app, this is immediately useful as support in WebKit browsers is already very good. In other cases, you’ll have to use your own best judgement based on your needs and audience.
One thing to keep in mind is that if you’re using web fonts, the entire font will be downloaded even if only one character is used. That said, the font shouldn’t be downloaded if none of the characters within the Unicode range are present in a given page.
As ever, there are pros and cons to using unicode-range as well as varied but increasing support in browsers. It remains a useful tool to understand and have in your toolkit for when the right moment comes along. |
2011 |
Drew McLellan |
drewmclellan |
2011-12-01T00:00:00+00:00 |
https://24ways.org/2011/creating-custom-font-stacks-with-unicode-range/ |
code |
| 242 |
Creating My First Chrome Extension |
Writing a Chrome Extension isn’t as scary at it seems!
Not too long ago, I used a Chrome extension called 20 Cubed. I’m far-sighted, and being a software engineer makes it difficult to maintain distance vision. So I used 20 Cubed to remind myself to look away from my screen and rest my eyes. I loved its simple interface and design. I loved it so much, I often forgot to turn it off in the middle of presentations, where it would take over my entire screen. Oops.
Unfortunately, the developer stopped updating the extension and removed it from Chrome’s extension library. I was so sad. None of the other eye rest extensions out there matched my design aesthetic, so I decided to create my own! Want to do the same?
Fortunately, Google has some respectable documentation on how to create an extension. And remember, Chrome extensions are just HTML, CSS, and JavaScript. You can add libraries and frameworks, or you can just code the “old-fashioned” way. Sky’s the limit!
Setup
But first, some things you’ll need to know about before getting started:
Callbacks
Timeouts
Chrome Dev Tools
Developing with Chrome extension methods requires a lot of callbacks. If you’ve never experienced the joy of callback hell, creating a Chrome extension will introduce you to this concept. However, things can get confusing pretty quickly. I’d highly recommend brushing up on that subject before getting started.
Hyperbole and a Half
Timeouts and Intervals are another thing you might want to brush up on. While creating this extension, I didn’t consider the fact that I’d be juggling three timers. And I probably would’ve saved time organizing those and reading up on the Chrome extension Alarms documentation beforehand. But more on that in a bit.
On the note of organization, abstraction is important! You might have any combination of the following:
The Chrome extension options page
The popup from the Chrome Menu
The windows or tabs you create
The background scripts
And that can get unwieldy. You might also edit the existing tabs or windows in the browser, which you’ll probably want as a separate script too. Note that this tutorial only covers creating your own customized window rather than editing existing windows or tabs.
Alright, now that you know all that up front, let’s get going!
Documentation
TL;DR READ THE DOCS.
A few things to get started:
Read Google’s primer on browser extensions
Have a look at their Getting started tutorial
Check out their overview on Chrome Extensions
This overview discusses the Chrome extension files, architecture, APIs, and communication between pages. Funnily enough, I only discovered the Overview page after creating my extension.
The manifest.json file gives the browser information about the extension, including general information, where to find your extension files and icons, and API permissions required. Here’s what my manifest.json looked like, for example:
https://github.com/jennz0r/eye-rest/blob/master/manifest.json
Because I’m a visual learner, I found the images that describe the extension’s architecture most helpful.
To clarify this diagram, the background.js file is the extension’s event handler. It’s constantly listening for browser events, which you’ll feed to it using the Chrome Extension API. Google says that an effective background script is only loaded when it is needed and unloaded when it goes idle.
The Popup is the little window that appears when you click on an extension’s icon in the Chrome Menu. It consists of markup and scripts, and you can tell the browser where to find it in the manifest.json under page_action: { "default_popup": FILE_NAME_HERE }.
The Options page is exactly as it says. This displays customizable options only visible to the user when they either right-click on the Chrome menu and choose “Options” under an extension. This also consists of markup and scripts, and you can tell the browser where to find it in the manifest.json under options_page: FILE_NAME_HERE.
Content scripts are any scripts that will interact with any web windows or tabs that the user has open. These scripts will also interact with any tabs or windows opened by your extension.
Debugging
A quick note: don’t forget the debugging tutorial!
Just like any other Chrome window, every piece of an extension has an inspector and dev tools. If (read: when) you run into errors (as I did), you’re likely to have several inspector windows open – one for the background script, one for the popup, one for the options, and one for the window or tab the extension is interacting with.
For example, I kept seeing the error “This request exceeds the MAX_WRITE_OPERATIONS_PER_HOUR quota.” Well, it turns out there are limitations on how often you can sync stored information.
Another error I kept seeing was “Alarm delay is less than minimum of 1 minutes. In released .crx, alarm “ALARM_NAME_HERE” will fire in approximately 1 minutes”. Well, it turns out there are minimum interval times for alarms.
Chrome Extension creation definitely benefits from debugging skills. Especially with callbacks and listeners, good old fashioned console.log can really help!
Me adding a ton of `console.log`s while trying to debug my alarms.
Eye Rest Functionality
Ok, so what is the extension I created? Again, it’s a way to rest your eyes every twenty minutes for twenty seconds. So, the basic functionality should look like the following:
If the extension is running AND
If the user has not clicked Pause in the Popup HTML AND
If the counter in the Popup HTML is down to 00:00 THEN
Open a new window with Timer HTML AND
Start a 20 sec countdown in Timer HTML AND
Reset the Popup HTML counter to 20:00
If the Timer HTML is down to 0 sec THEN
Close that window. Rinse. Repeat.
Sounds simple enough, but wow, these timers became convoluted! Of all the Chrome extensions I decided to create, I decided to make one that’s heavily dependent on time, intervals, and having those in sync with each other. In other words, I made this unnecessarily complicated and didn’t realize until I started coding.
For visual reference of my confusion, check out the GitHub repository for Eye Rest. (And yes, it’s a pun.)
API
Now let’s discuss the APIs that I used to build this extension.
Alarms
What even are alarms? I didn’t know either.
Alarms are basically Chrome’s setTimeout and setInterval. They exist because, as Google says…
DOM-based timers, such as window.setTimeout() or window.setInterval(), are not honored in non-persistent background scripts if they trigger when the event page is dormant.
For more information, check out this background migration doc.
One interesting note about alarms in Chrome extensions is that they are persistent. Garbage collection with Chrome extension alarms seems unreliable at best. I didn’t have much luck using the clearAll method to remove alarms I created on previous extension loads or installs. A workaround (read: hack) is to specify a unique alarm name every time your extension is loaded and clearing any other alarms without that unique name.
Background Scripts
For Eye Rest, I have two background scripts. One is my actual initializer and event listener, and the other is a helpers file.
I wanted to share a couple of functions between my Background and Popup scripts. Specifically, the clearAndCreateAlarm function. I wanted my background script to clear any existing alarms, create a new alarm, and add remaining time until the next alarm to local storage immediately upon extension load. To make the function available to the Background script, I added helpers.js as the first item under background > scripts in my manifest.json.
I also wanted my Popup script to do the same things when the user has unpaused the extension’s functionality. To make the function available to the Popup script, I just include the helpers script in the Popup HTML file.
Other APIs
Windows
I use the Windows API to create the Timer window when the time of my alarm is up. The window creation is initiated by my Background script.
One day, while coding late into the evening, I found it very confusing that the window.create method included url as an option. I assumed it was meant to be an external web address. A friend pondered that there must be an option to specify the window’s HTML. Until then, it hadn’t dawned on me that the url could be relative. Duh. I was tired!
I pass the timer.html as the url option, as well as type, size, position, and other visual options.
Storage
Maybe you want to pass information back and forth between the Background script and your Popup script? You can do that using Chrome or local storage. One benefit of using local storage over Chrome’s storage is avoiding quotas and write operation maximums.
I wanted to pass the time at which the latest alarm was set, the time to the next alarm, and whether or not the timer is paused between the Background and Popup scripts. Because the countdown should change every second, it’s quite complicated and requires lots of writes. That’s why I went with the user’s local storage. You can see me getting and setting those variables in my Background, Helper, and Popup scripts. Just search for date, nextAlarmTime, and isPaused.
Declarative Content
The Declarative Content API allows you to show your extension’s page action based on several type of matches, without needing to take a host permission or inject a content script. So you’ll need this to get your extension to work in the browser!
You can see me set this in my Background script. Because I want my extension’s popup to appear on every page one is browsing, I leave the page matchers empty.
There are many more APIs for Chrome apps and extensions, so make sure to surf around and see what features are available!
The Extension
Here’s what my original Popup looked like before I added styles.
And here’s what it looks like with new styles. I guess I’m going for a Nickelodeon feel.
And here’s the Timer window and Popup together!
Publishing
Publishing is a cinch. You just zip up your files, create a new or use an existing Google Developer account, upload the files, add some details, and pay a one time $5 fee. That’s all! Then your extension will be available on the Chrome extension store! Neato :D
My extension is now available for you to install.
Conclusion
I thought creating a time based Chrome Extension would be quick and easy. I was wrong. It was more complicated than I thought! But it’s definitely achievable with some time, persistence, and good ole Google searches.
Eventually, I’d like to add more interactive elements to Eye Rest. For example, hitting the YouTube API to grab a silly or cute video as a reward for looking away during the 20 sec countdown and not closing the timer window. This harkens back to one of my first web projects, Toothtimer, from 2012. Or maybe a way to change the background colors of the Timer and Popup!
Either way, with Eye Rest’s framework built out, I’m feeling fearless about future feature adds! Building this Chrome extension took some broken nails, achy shoulders, and tired eyes, but now Eye Rest can tell me to give my eyes a break every 20 minutes. |
2018 |
Jennifer Wong |
jenniferwong |
2018-12-05T00:00:00+00:00 |
https://24ways.org/2018/my-first-chrome-extension/ |
code |
| 83 |
Cut Copy Paste |
Long before I got into this design thing, I was heavily into making my own music inspired by the likes of Coldcut and Steinski. I would scour local second-hand record shops in search of obscure beats, loops and bits of dialogue in the hope of finding that killer sample I could then splice together with other things to make a huge hit that everyone would love. While it did eventually lead to a record contract and getting to release a few 12″ singles, ultimately I knew I’d have to look for something else to pay the bills.
I may not make my own records any more, but the approach I took back then – finding (even stealing) things, cutting and pasting them into interesting combinations – is still at the centre of how I work, only these days it’s pretty much bits of code rather than bits of vinyl. Over the years I’ve stored these little bits of code (some I’ve found, some I’ve created myself) in Evernote, ready to be dialled up whenever I need them.
So when Drew got in touch and asked if I’d like to do something for this year’s 24 ways I thought it might be kind of cool to share with you a few of these snippets that I find really useful. Think of these as a kind of coding mix tape; but remember – don’t just copy as is: play around, combine and remix them into other wonderful things.
Some of this stuff is dirty; some of it will make hardcore programmers feel ill. For those people, remember this – while you were complaining about the syntax, I made something.
Create unique colours
Let’s start right away with something I stole. Well, actually it was given away at the time by Matt Biddulph who was then at Dopplr before Nokia destroyed it. Imagine you have thousands of words and you want to assign each one a unique colour. Well, Matt came up with a crazily simple but effective way to do that using an MD5 hash. Just encode said word using an MD5 hash, then take the first six characters of the string you get back to create a hexadecimal colour representation.
I can’t guarantee that it will be a harmonious colour palette, but it’s still really useful. The thing I love the most about this technique is the left-field thinking of using an encryption system to create colours! Here’s an example using JavaScript:
// requires the MD5 library available at http://pajhome.org.uk/crypt/md5
function MD5Hex(str){
result = MD5.hex(str).substring(0, 6);
return result;
}
Make something breathe using a sine wave
I never paid attention in school, especially during double maths. As a matter of fact, the only time I received corporal punishment – several strokes of the ruler – was in maths class. Anyway, if they had shown me then how beautiful mathematics actually is, I might have paid more attention. Here’s a little example of how a sine wave can be used to make something appear to breathe.
I recently used this on an Arduino project where an LED ring surrounding a button would gently breathe. Because of that it felt much more inviting. I love mathematics.
for(int i = 0; i<360; i++){
float rad = DEG_TO_RAD * i;
int sinOut = constrain((sin(rad) * 128) + 128, 0, 255);
analogWrite(LED, sinOut);
delay(10);
}
Snap position to grid
This is so elegant I love it, and it was shown to me by Gary Burgess, or Boom Boom as myself and others like to call him. It snaps a position, in this case the X-position, to a grid. Just define your grid size (say, twenty pixels) and you’re good.
snappedXpos = floor( xPos / gridSize) * gridSize;
Calculate the distance between two objects
For me, interaction design is about the relationship between two objects: you and another object; you and another person; or simply one object to another. How close these two things are to each other can be a handy thing to know, allowing you to react to that information within your design. Here’s how to calculate the distance between two objects in a 2-D plane:
deltaX = round(p2.x-p1.x);
deltaY = round(p2.y-p1.y);
diff = round(sqrt((deltaX*deltaX)+(deltaY*deltaY)));
Find the X- and Y-position between two objects
What if you have two objects and you want to place something in-between them? A little bit of interruption and disruption can be a good thing. This small piece of code will allow you to place an object in-between two other objects:
// set the position: 0.5 = half-way
float position = 0.5;
float x = x1 + (x2 - x1) *position;
float y = y1 + (y2 - y1) *position;
Distribute objects equally around a circle
More fun with maths, this time adding cosine to our friend sine. Let’s say you want to create a circular navigation of arbitrary elements (yeah, Jakob, you heard), or you want to place images around a circle. Well, this piece of code will do just that. You can adjust the size of the circle by changing the distance variable and alter the number of objects with the numberOfObjects variable. Example below is for use in Processing.
// Example for Processing available for free download at processing.org
void setup() {
size(800,800);
int numberOfObjects = 12;
int distance = 100;
float inc = (TWO_PI)/numberOfObjects;
float x,y;
float a = 0;
for (int i=0; i < numberOfObjects; i++) {
x = (width/2) + sin(a)*distance;
y = (height/2) + cos(a)*distance;
ellipse(x,y,10,10);
a += inc;
}
}
Use modulus to make a grid
The modulus operator, represented by %, returns the remainder of a division. Fallen into a coma yet? Hold on a minute – this seemingly simple function is very powerful in lots of ways. At a simple level, you can use it to determine if a number is odd or even, great for creating alternate row colours in a table for instance:
boolean checkForEven(numberToCheck) {
if (numberToCheck % 2 == 0)
return true;
} else {
return false;
}
}
That’s all well and good, but here’s a use of modulus that might very well blow your mind. Construct a grid with only a few lines of code. Again the example is in Processing but can easily be ported to any other language.
void setup() {
size(600,600);
int numItems = 120;
int numOfColumns = 12;
int xSpacing = 40;
int ySpacing = 40;
int totalWidth = xSpacing*numOfColumns;
for (int i=0; i < numItems; i++) {
ellipse(floor((i*xSpacing)%totalWidth),floor((i*xSpacing)/totalWidth)*ySpacing,10,10);
}
}
Not all the bits of code I keep around are for actual graphical output. I also have things that are very utilitarian, but which I still consider part of the design process. Here’s a couple of things that I’ve found really handy lately in my design workflow. They may be a little specific, but I hope they demonstrate that it’s not about working harder, it’s about working smarter.
Merge CSV files into one file
Recently, I’ve had to work with huge – about 1GB – CSV text files that I then needed to combine into one master CSV file so I could then process the data. Opening up each text file and then copying and pasting just seemed really dumb, not to mention slow, so I thought there must be a better way. After some Googling I found this command line script that would combine .txt files into one file and add a new line after each:
awk 1 *.txt > finalfile.txt
But that wasn’t what I was ideally after. I wanted to merge the CSV files, keeping the first row of the first file (the column headings) and then ignore the first row of subsequent files. Sure enough I found the answer after some Googling and it worked like a charm. Apologies to the original author but I can’t remember where I found it, but you, sir or madam, are awesome. Save this as a shell script:
FIRST=
for FILE in *.csv
do
exec 5<"$FILE" # Open file
read LINE <&5 # Read first line
[ -z "$FIRST" ] && echo "$LINE" # Print it only from first file
FIRST="no"
cat <&5 # Print the rest directly to standard output
exec 5<&- # Close file
# Redirect stdout for this section into file.out
done > file.out
Create a symbolic link to another file or folder
Oftentimes, I’ll find myself hunting through a load of directories to load a file to be processed, like a CSV file. Use a symbolic link (in the Terminal) to place a link on your desktop or wherever is most convenient and it’ll save you loads of time. Especially great if you’re going through a Java file dialogue box in Processing or something that doesn’t allow the normal Mac dialog box or aliases.
cd /DirectoryYouWantShortcutToLiveIn
ln -s /Directory/You/Want/ShortcutTo/ TheShortcut
You can do it, in the mix
I hope you’ve found some of the above useful and that they’ve inspired a few ideas here and there. Feel free to tell me better ways of doing things or offer up any other handy pieces of code. Most of all though, collect, remix and combine the things you discover to make lovely new things. |
2012 |
Brendan Dawes |
brendandawes |
2012-12-17T00:00:00+00:00 |
https://24ways.org/2012/cut-copy-paste/ |
code |
| 320 |
DOM Scripting Your Way to Better Blockquotes |
Block quotes are great. I don’t mean they’re great for indenting content – that would be an abuse of the browser’s default styling. I mean they’re great for semantically marking up a chunk of text that is being quoted verbatim. They’re especially useful in blog posts.
<blockquote>
<p>Progressive Enhancement, as a label for a strategy for Web design,
was coined by Steven Champeon in a series of articles and presentations
for Webmonkey and the SxSW Interactive conference.</p>
</blockquote>
Notice that you can’t just put the quoted text directly between the <blockquote> tags. In order for your markup to be valid, block quotes may only contain block-level elements such as paragraphs.
There is an optional cite attribute that you can place in the opening <blockquote> tag. This should contain a URL containing the original text you are quoting:
<blockquote cite="http://en.wikipedia.org/wiki/Progressive_Enhancement">
<p>Progressive Enhancement, as a label for a strategy for Web design,
was coined by Steven Champeon in a series of articles and presentations
for Webmonkey and the SxSW Interactive conference.</p>
</blockquote>
Great! Except… the default behavior in most browsers is to completely ignore the cite attribute. Even though it contains important and useful information, the URL in the cite attribute is hidden.
You could simply duplicate the information with a hyperlink at the end of the quoted text:
<blockquote cite="http://en.wikipedia.org/wiki/Progressive_Enhancement">
<p>Progressive Enhancement, as a label for a strategy for Web design,
was coined by Steven Champeon in a series of articles and presentations
for Webmonkey and the SxSW Interactive conference.</p>
<p class="attribution">
<a href="http://en.wikipedia.org/wiki/Progressive_Enhancement">source</a>
</p>
</blockquote>
But somehow it feels wrong to have to write out the same URL twice every time you want to quote something. It could also get very tedious if you have a lot of quotes.
Well, “tedious” is no problem to a programming language, so why not use a sprinkling of DOM Scripting? Here’s a plan for generating an attribution link for every block quote with a cite attribute:
Write a function called prepareBlockquotes.
Begin by making sure the browser understands the methods you will be using.
Get all the blockquote elements in the document.
Start looping through each one.
Get the value of the cite attribute.
If the value is empty, continue on to the next iteration of the loop.
Create a paragraph.
Create a link.
Give the paragraph a class of “attribution”.
Give the link an href attribute with the value from the cite attribute.
Place the text “source” inside the link.
Place the link inside the paragraph.
Place the paragraph inside the block quote.
Close the for loop.
Close the function.
Here’s how that translates to JavaScript:
function prepareBlockquotes() {
if (!document.getElementsByTagName || !document.createElement || !document.appendChild) return;
var quotes = document.getElementsByTagName("blockquote");
for (var i=0; i<quotes.length; i++) {
var source = quotes[i].getAttribute("cite");
if (!source) continue;
var para = document.createElement("p");
var link = document.createElement("a");
para.className = "attribution";
link.setAttribute("href",source);
link.appendChild(document.createTextNode("source"));
para.appendChild(link);
quotes[i].appendChild(para);
}
}
Now all you need to do is trigger that function when the document has loaded:
window.onload = prepareBlockquotes;
Better yet, use Simon Willison’s handy addLoadEvent function to queue this function up with any others you might want to execute when the page loads.
That’s it. All you need to do is save this function in a JavaScript file and reference that file from the head of your document using <script> tags.
You can style the attribution link using CSS. It might look good aligned to the right with a smaller font size.
If you’re looking for something to do to keep you busy this Christmas, I’m sure that this function could be greatly improved. Here are a few ideas to get you started:
Should the text inside the generated link be the URL itself?
If the block quote has a title attribute, how would you take its value and use it as the text inside the generated link?
Should the attribution paragraph be placed outside the block quote? If so, how would you that (remember, there is an insertBefore method but no insertAfter)?
Can you think of other instances of useful information that’s locked away inside attributes? Access keys? Abbreviations? |
2005 |
Jeremy Keith |
jeremykeith |
2005-12-05T00:00:00+00:00 |
https://24ways.org/2005/dom-scripting-your-way-to-better-blockquotes/ |
code |
| 31 |
Dealing with Emergencies in Git |
The stockings were hung by the chimney with care,
In hopes that version control soon would be there.
This summer I moved to the UK with my partner, and the onslaught of the Christmas holiday season began around the end of October (October!). It does mean that I’ve had more than a fair amount of time to come up with horrible Git analogies for this article. Analogies, metaphors, and comparisons help the learner hook into existing mental models about how a system works. They only help, however, if the learner has enough familiarity with the topic at hand to make the connection between the old and new information.
Let’s start by painting an updated version of Clement Clarke Moore’s Christmas living room. Empty stockings are hung up next to the fireplace, waiting for Saint Nicholas to come down the chimney and fill them with small treats. Holiday treats are scattered about. A bowl of mixed nuts, the holiday nutcracker, and a few clementines. A string of coloured lights winds its way up an evergreen.
Perhaps a few of these images are familiar, or maybe they’re just settings you’ve seen in a movie. It doesn’t really matter what the living room looks like though. The important thing is to ground yourself in your own experiences before tackling a new subject. Instead of trying to brute-force your way into new information, as an adult learner constantly ask yourself: ‘What is this like? What does this remind me of? What do I already know that I can use to map out this new territory?’ It’s okay if the map isn’t perfect. As you refine your understanding of a new topic, you’ll outgrow the initial metaphors, analogies, and comparisons.
With apologies to Mr. Moore, let’s give it a try.
Getting Interrupted in Git
When on the roof there arose such a clatter!
You’re happily working on your software project when all of a sudden there are freaking reindeer on the roof! Whatever you’ve been working on is going to need to wait while you investigate the commotion.
If you’ve got even a little bit of experience working with Git, you know that you cannot simply change what you’re working on in times of emergency. If you’ve been doing work, you have a dirty working directory and you cannot change branches, or push your work to a remote repository while in this state.
Up to this point, you’ve probably dealt with emergencies by making a somewhat useless commit with a message something to the effect of ‘switching branches for a sec’. This isn’t exactly helpful to future you, as commits should really contain whole ideas of completed work. If you get interrupted, especially if there are reindeer on the roof, the chances are very high that you weren’t finished with what you were working on.
You don’t need to make useless commits though. Instead, you can use the stash command. This command allows you to temporarily set aside all of your changes so that you can come back to them later. In this sense, stash is like setting your book down on the side table (or pushing the cat off your lap) so you can go investigate the noise on the roof. You aren’t putting your book away though, you’re just putting it down for a moment so you can come back and find it exactly the way it was when you put it down.
Let’s say you’ve been working in the branch waiting-for-st-nicholas, and now you need to temporarily set aside your changes to see what the noise was on the roof:
$ git stash
After running this command, all uncommitted work will be temporarily removed from your working directory, and you will be returned to whatever state you were in the last time you committed your work.
With the book safely on the side table, and the cat safely off your lap, you are now free to investigate the noise on the roof. It turns out it’s not reindeer after all, but just your boss who thought they’d help out by writing some code on the project you’ve been working on. Bless. Rolling your eyes, you agree to take a look and see what kind of mischief your boss has gotten themselves into this time.
You fetch an updated list of branches from the remote repository, locate the branch your boss had been working on, and checkout a local copy:
$ git fetch
$ git branch -r
$ git checkout -b helpful-boss-branch origin/helpful-boss-branch
You are now in a local copy of the branch where you are free to look around, and figure out exactly what’s going on.
You sigh audibly and say, ‘Okay. Tell me what was happening when you first realised you’d gotten into a mess’ as you look through the log messages for the branch.
$ git log --oneline
$ git log
By using the log command you will be able to review the history of the branch and find out the moment right before your boss ended up stuck on your roof.
You may also want to compare the work your boss has done to the main branch for your project. For this article, we’ll assume the main branch is named master.
$ git diff master
Looking through the commits, you may be able to see that things started out okay but then took a turn for the worse.
Checking out a single commit
Using commands you’re already familiar with, you can rewind through history and take a look at the state of the code at any moment in time by checking out a single commit, just like you would a branch.
Using the log command, locate the unique identifier (commit hash) of the commit you want to investigate. For example, let’s say the unique identifier you want to checkout is 25f6d7f.
$ git checkout 25f6d7f
Note: checking out '25f6d7f'.
You are in 'detached HEAD' state. You can look around,
make experimental changes and commit them, and you can
discard any commits you make in this state without
impacting any branches by performing another checkout.
If you want to create a new branch to retain commits you create, you may do so (now or later) by using @-b@ with the checkout command again. Example:
$ git checkout -b new_branch_name
HEAD is now at 25f6d7f... Removed first paragraph.
This is usually where people start to panic. Your boss screwed something up, and now your HEAD is detached. Under normal circumstances, these words would be a very good reason to panic.
Take a deep breath. Nothing bad is going to happen. Being in a detached HEAD state just means you’ve temporarily disconnected from a known chain of events. In other words, you’re currently looking at the middle of a story (or branch) about what happened – and you’re not at the endpoint for this particular story.
Git allows you to view the history of your repository as a timeline (technically it’s a directed acyclic graph). When you make commits which are not associated with a branch, they are essentially inaccessible once you return to a known branch. If you make commits while you’re in a detached HEAD state, and then try to return to a known branch, Git will give you a warning and tell you how to save your work.
$ git checkout master
Warning: you are leaving 1 commit behind, not connected to
any of your branches:
7a85788 Your witty holiday commit message.
If you want to keep them by creating a new branch, this may be a good time to do so with:
$ git branch new_branch_name 7a85788
Switched to branch 'master'
Your branch is up-to-date with 'origin/master'.
So, if you want to save the commits you’ve made while in a detached HEAD state, you simply need to put them on a new branch.
$ git branch saved-headless-commits 7a85788
With this trick under your belt, you can jingle around in history as much as you’d like. It’s not like sliding around on a timeline though. When you checkout a specific commit, you will only have access to the history from that point backwards in time. If you want to move forward in history, you’ll need to move back to the branch tip by checking out the branch again.
$ git checkout helpful-boss-branch
You’re now back to the present. Your HEAD is now pointing to the endpoint of a known branch, and so it is no longer detached. Any changes you made while on your adventure are safely stored in a new branch, assuming you’ve followed the instructions Git gave you. That wasn’t so scary after all, now, was it?
Back to our reindeer problem.
If your boss is anything like the bosses I’ve worked with, chances are very good that at least some of their work is worth salvaging. Depending on how your repository is structured, you’ll want to capture the good work using one of several different methods.
Back in the living room, we’ll use our bowl of nuts to illustrate how you can rescue a tiny bit of work.
Saving just one commit
About that bowl of nuts. If you’re like me, you probably had some favourite kinds of nuts from an assorted collection. Walnuts were generally the most satisfying to crack open. So, instead of taking the entire bowl of nuts and dumping it into a stocking (merging the stocking and the bowl of nuts), we’re just going to pick out one nut from the bowl. In Git terms, we’re going to cherry-pick a commit and save it to another branch.
First, checkout the main branch for your development work. From this branch, create a new branch where you can copy the changes into.
$ git checkout master
$ git checkout -b rescue-the-boss
From your boss’s branch, helpful-boss-branch locate the commit you want to keep.
$ git log --oneline helpful-boss-branch
Let’s say the commit ID you want to keep is e08740b. From your rescue branch, use the command cherry-pick to copy the changes into your current branch.
$ git cherry-pick e08740b
If you review the history of your current branch again, you will see you now also have the changes made in the commit in your boss’s branch.
At this point you might need to make a few additional fixes to help your boss out. (You’re angling for a bonus out of all this. Go the extra mile.) Once you’ve made your additional changes, you’ll need to add that work to the branch as well.
$ git add [filename(s)]
$ git commit -m "Building on boss's work to improve feature X."
Go ahead and test everything, and make sure it’s perfect. You don’t want to introduce your own mistakes during the rescue mission!
Uploading the fixed branch
The next step is to upload the new branch to the remote repository so that your boss can download it and give you a huge bonus for helping you fix their branch.
$ git push -u origin rescue-the-boss
Cleaning up and getting back to work
With your boss rescued, and your bonus secured, you can now delete the local temporary branches.
$ git branch --delete rescue-the-boss
$ git branch --delete helpful-boss-branch
And settle back into your chair to wait for Saint Nicholas with your book, your branch, and possibly your cat.
$ git checkout waiting-for-st-nicholas
$ git stash pop
Your working directory has been returned to exactly the same state you were in at the beginning of the article.
Having fun with analogies
I’ve had a bit of fun with analogies in this article. But sometimes those little twists on ideas can really help someone pick up a new idea (git stash: it’s like when Christmas comes around and everyone throws their fashion sense out the window and puts on a reindeer sweater for the holiday party; or git bisect: it’s like trying to find that one broken light on the string of Christmas lights). It doesn’t matter if the analogy isn’t perfect. It’s just a way to give someone a temporary hook into a concept in a way that makes the concept accessible while the learner becomes comfortable with it. As the learner’s comfort increases, the analogies can drop away, making room for the technically correct definition of how something works.
Or, if you’re like me, you can choose to never grow old and just keep mucking about in the analogies. I’d argue it’s a lot more fun to play with a string of Christmas lights and some holiday cheer than a directed acyclic graph anyway. |
2014 |
Emma Jane Westby |
emmajanewestby |
2014-12-02T00:00:00+00:00 |
https://24ways.org/2014/dealing-with-emergencies-in-git/ |
code |
| 202 |
Design Systems and CSS Grid |
Recently, my client has been looking at creating a few new marketing pages for their website. They currently have a design system in place but they’re looking to push this forward into 2018 with some small and possibly some larger changes.
To start with we are creating a couple of new marketing pages. As well as making use of existing components within the design systems component library there are a couple of new components. Looking at the first couple of sketch files I felt this would be a great opportunity to use CSS Grid, to me the newer components need to be laid out on that page and grid would help with this perfectly.
As well as this layout of the new components and the text within it, imagery would be used that breaks out of the grid and pushes itself into the spaces where the text is aligned.
The existing grid system
When the site was rebuilt in 2015 the team decided to make use of Sass and Susy, a “lightweight grid-layout engine using Sass”. It was built separating the grid system from the components that would be laid out on the page with a container, a row, an optional column, and a block.
To make use of the grid system on a page for a component that would take the full width of the row you would have to write something like this:
<div class="grid-container">
<div class="grid-row">
<div class="grid-column-4">
<div class="grid-block">
<!-- component code here -->
</div>
</div>
</div>
</div>
Using a grid system similar to this can easily create quite the tag soup. It could fill the HTML full of divs that may become complex to understand and difficult to edit.
Although there is this reliance on several <div>s to lay out the components on a page it does allow a tidy way to place the component code within that page. It abstracts the layout of the page to its own code, its own system, so the components can ‘fit’ where needed.
The requirements of the new grid system
Moving forward I set myself some goals for what I’d like to have achieved in this new grid system:
It needs to behave like the existing grid systems
We are not ripping up the existing grid system, it would be too much work, for now, to retrofit all of the existing components to work in a grid that has a different amount of columns, and spacing at various viewport widths.
Allow full-width components
Currently the grid system is a 14 column grid that becomes centred on the page when viewport is wide enough. We have, in the past, written some CSS that would allow for a full-width component, but his had always felt like a hack. We want the option to have a full-width element as part of the new grid system, not something that needs CSS to fight against.
Less of a tag soup
Ideally we want to end up writing less HTML to layout the page. Although the existing system can be quite clear as to what each element is doing, it can also become a little laborious in working out what each grid row or block is doing where.
I would like to move the layout logic to CSS as much as is possible, potentially creating some utility classes or additional ‘layout classes’ for the components.
Easier for people to use and author
With many people using the existing design systems codebase we need to create a new grid system that is as easy or easier to use than the existing one. I think and hope this would be helped by removing as many <div>s as needed and would require new documentation and examples, and potentially some initial training.
Separating layout from style
There still needs to be a separation of layout from the styles for the component. To allow for the component itself to be placed wherever needed in the page we need to make sure that the CSS for the layout is a separate entity to the CSS for that styling.
With these base requirements I took to CodePen and started working on some throwaway code to get started.
Making the new grid(s)
The Full-Width Grid
To start with I created a grid that had three columns, one for the left, one for the middle, and one for the right. This would give the full-width option to components.
Thankfully, one of Rachel Andrew’s many articles on Grid discussed this exact requirement of the new grid system to break out with Grid.
I took some of the code in the examples and edited to make grid we needed.
.container {
display: grid;
grid-template-columns:
[full-start]
minmax(.75em, 1fr)
[main-start]
minmax(0, 1008px)
[main-end]
minmax(.75em, 1fr)
[full-end];
}
We are declaring a grid, we have four grid column lines which we name and we define how the three columns they create react to the viewport width. We have a left and right column that have a minimum of 12px, and a central column with a maximum width of 1008px.
Both left and right columns fill up any additional space if the viewport is wider that 1032px wide. We are also not declaring any gutters to this grid, the left and right columns would act as gutters at smaller viewports.
At this point I noticed that older versions of Sass cannot parse the brackets in this code. To combat this I used Sass’ unquote method to wrap around the value of the grid-template-column.
.container {
display: grid;
grid-template-columns:
unquote("
[full-start]
minmax(.75em, 1fr)
[main-start]
minmax(0, 1008px)
[main-end]
minmax(.75em, 1fr)
[full-end]
");
}
The existing codebase makes use of Sass variables, mixins and functions so to remove that would be a problem, but luckily the version of Sass used is up-to-date (note: example CodePens will be using CSS).
The initial full-width grid displays on a webpage as below:
The 14 column grid
I decided to work out the 14 column grid as a separate prototype before working out how it would fit within the full-width grid. This grid is very similar to the 12 column grids that have been used in web design. Here we need 14 columns with a gutter between each one.
Along with the many other resources on Grid, Mozilla’s MDN site had a page on common layouts using CSS Grid. This gave me the perfect CSS I needed to create my grid and I edited it as required:
.inner {
display: grid;
grid-template-columns: repeat(14, [col-start] 1fr);
grid-gap: .75em;
}
We, again, are declaring a grid, and we are splitting up the available space by creating 14 columns with 1 fr-unit and giving each one a starting line named col-start.
This grid would display on web page as below:
Bringing the grids together
Now that we have got the two grids we need to help fulfil our requirements we need to put them together so that they are actually we we need.
The subgrid
There is no subgrid in CSS, yet. To workaround this for the new grid system we could nest the 14 column grid inside the full-width grid.
In the HTML we nest the 14 column inner grid inside the full-width container.
<div class="container">
<div class="inner">
</div>
</div>
So that the inner knows where to be laid out within the container we tell it what column to start and end with, with this code it would be the start and end of the main column.
.inner {
display: grid;
grid-column: main-start / main-end;
grid-template-columns: repeat(14, [col-start] 1fr);
grid-gap: .75em;
}
The CSS for the container remains unchanged.
This works, but we have added another div to our HTML. One of our requirements is to try and remove the potential for tag soup.
The faux subgrid subgrid
I wanted to see if it would be possible to place the CSS for the 14 column grid within the CSS for the full-width grid. I replaced the CSS for the main grid and added the grid-column-gap to the .container.
.container {
display: grid;
grid-gap: .75em;
grid-template-columns:
[full-start]
minmax(.75em, 1fr)
[main-start]
repeat(14, [col-start] 1fr)
[main-end]
minmax(.75em, 1fr)
[full-end];
}
What this gave me was a 16 column grid. I was unable to find a way to tell the main grid, the grid betwixt main-start and main-end to be a maximum of 1008px as required.
I trawled the internet to find if it was possible to create our main requirement, a 14 column grid which also allows for full-width components. I found that we could not reverse minmax to minmax(1fr, 72px) as 1fr is not allowed as a minimum if there is a maximum. I tried working out if we could make the min larger than its max but in minmax it would be ignored.
I was struggling, I was hoping for a cleaner version of the grid system we currently use but getting to the point where needing that extra <div> would be a necessity.
At 3 in the morning, when I was failing to get to sleep, my mind happened upon an question: “Could you use calc?”
At some point I drifted back to sleep so the next day I set upon seeing if this was possible. I knew that the maximum width of the central grid needed to be 1008px. The left and right columns needed to be however many pixels were left in the viewport divided by 2. In CSS it looked like I would need to use calc twice. The first time to takeaway 1008px from 100% of the viewport width and the second to divide that result by 2.
calc(calc(100% - 1008px) / 2)
The CSS above was part of the value that I would need to include in the declaration for the grid.
.container {
display: grid;
grid-gap: .75em;
grid-template-columns:
[full-start]
minmax(calc(calc(100% - 1008px) / 2), 1fr)
[main-start]
repeat(14, [col-start] 1fr)
[main-end]
minmax(calc(calc(100% - 1008px) / 2), 1fr)
[full-end];
}
We have created the grid required. A full-width grid, with a central 14 column grid, using fewer <div> elements.
See the Pen Design Systems and CSS Grid, 6 by Stuart Robson (@sturobson) on CodePen.
Success!
Progressive enhancement
Now that we have created the grid system required we need to back-track a little.
Not all browsers support Grid, over the last 9 months or so this has gotten a lot better. However there will still be browsers that visit that potentially won’t have support. The effort required to make the grid system fall back for these browsers depends on your product or sites browser support.
To determine if we will be using Grid or not for a browser we will make use of feature queries. This would mean that any version of Internet Explorer will not get Grid, as well as some mobile browsers and older versions of other browsers.
@supports (display: grid) {
/* Styles for browsers that support Grid */
}
If a browser does not pass the requirements for @supports we will fallback to using flexbox where possible, and if that is not supported we are happy for the page to be laid out in one column.
A website doesn’t have to look the same in every browser after all.
A responsive grid
We started with the big picture, how the grid would be at a large viewport and the grid system we have created gets a little silly when the viewport gets smaller.
At smaller viewports we have a single column layout where every item of content, every component stacks atop each other. We don’t start to define a grid before we the viewport gets to 700px wide. At this point we have an 8 column grid and if the viewport gets to 1100px or wider we have our 14 column grid.
/*
* to start with there is no 'grid' just a single column
*/
.container {
padding: 0 .75em;
}
/*
* when we get to 700px we create an 8 column grid with
* a left and right area to breakout of the grid.
*/
@media (min-width: 700px) {
.container {
display: grid;
grid-gap: .75em;
grid-template-columns:
[full-start]
minmax(calc(calc(100% - 1008px) / 2), 1fr)
[main-start]
repeat(8, [col-start] 1fr)
[main-end]
minmax(calc(calc(100% - 1008px) / 2), 1fr)
[full-end];
padding: 0;
}
}
/*
* when we get to 1100px we create an 14 column grid with
* a left and right area to breakout of the grid.
*/
@media (min-width: 1100px) {
.container {
grid-template-columns:
[full-start]
minmax(calc(calc(100% - 1008px) / 2), 1fr)
[main-start]
repeat(14, [col-start] 1fr)
[main-end]
minmax(calc(calc(100% - 1008px) / 2), 1fr)
[full-end];
}
}
Being explicit in creating this there is some repetition that we could avoid, we will define the number of columns for the inner grid by using a Sass variable or CSS custom properties (more commonly termed as CSS variables).
Let’s use CSS custom properties. We need to declare the variable first by adding it to our stylesheet.
:root {
--inner-grid-columns: 8;
}
We then need to edit a few more lines. First make use of the variable for this line.
repeat(8, [col-start] 1fr)
/* replace with */
repeat(var(--inner-grid-columns), [col-start] 1fr)
Then at the 1100px breakpoint we would only need to change the value of the —inner-grid-columns value.
@media (min-width: 1100px) {
.container {
grid-template-columns:
[full-start]
minmax(calc(calc(100% - 1008px) / 2), 1fr)
[main-start]
repeat(14, [col-start] 1fr)
[main-end]
minmax(calc(calc(100% - 1008px) / 2), 1fr)
[full-end];
}
}
/* replace with */
@media (min-width: 1100px) {
.container {
--inner-grid-columns: 14;
}
}
See the Pen Design Systems and CSS Grid, 8 by Stuart Robson (@sturobson) on CodePen.
The final grid system
We have finally created our new grid for the design system. It stays true to the existing grid in place, adds the ability to break-out of the grid, removes a <div> that could have been needed for the nested 14 column grid.
We can move on to the new component.
Creating a new component
Back to the new components we are needing to create.
To me there are two components one of which is a slight variant of the first. This component contains a title, subtitle, a paragraph (potentially paragraphs) of content, a list, and a call to action.
To start with we should write the HTML for the component, something like this:
<article class="features">
<h3 class="features__title"></h3>
<p class="features__subtitle"></p>
<div class="features__content">
<p class="features__paragraph"></p>
</div>
<ul class="features__list">
<li></li>
<li></li>
</ul>
<a href="" class="features__button"></a>
</article>
To place the component on the existing grid is fine, but as child elements are not affected by the container grid we need to define another grid for the features component.
As the grid doesn’t get invoked until 700px it is possible to negate the need for a media query.
.features {
grid-column: col-start 1 / span 6;
}
@supports (display: grid) {
@media (min-width: 1100px) {
.features {
grid-column-end: 9;
}
}
}
We can also avoid duplication of declarations by making use of the grid-column shorthand and longhand. We need to write a little more CSS for the variant component, the one that will sit on the right side of the page too.
.features:nth-of-type(even) {
grid-column-start: 4;
grid-row: 2;
}
@supports (display: grid) {
@media (min-width: 1100px) {
.features:nth-of-type(even) {
grid-column-start: 9;
grid-column-end: 16;
}
}
}
We cannot place the items within features on the container grid as they are not direct children. To make this work we have to define a grid for the features component.
We can do this by defining the grid at the first breakpoint of 700px making use of CSS custom properties again to define how many columns there will need to be.
.features {
grid-column: col-start 1 / span 6;
--features-grid-columns: 5;
}
@supports (display: grid) {
@media (min-width: 700px) {
.features {
display: grid;
grid-gap: .75em;
grid-template-columns: repeat(var(--features-grid-columns), [col-start] 1fr);
}
}
}
@supports (display: grid) {
@media (min-width: 1100px) {
.features {
grid-column-end: 9;
--features-grid-columns: 7;
}
}
}
See the Pen Design Systems and CSS Grid, 10 by Stuart Robson (@sturobson) on CodePen.
Laying out the parts
Looking at the spec and reading several articles I feel there are two ways that I could layout the text of this component on the grid.
We could use the grid-column shorthand that incorporates grid-column-start and grid-column-end or we can make use of grid-template-areas.
grid-template-areas allow for a nice visual way of representing how the parts of the component would be laid out. We can take the the mock of the features on the grid and represent them in text in our CSS.
Within the .features rule we can add the relevant grid-template-areas value to represent the above.
.features {
display: grid;
grid-template-columns: repeat(var(--features-grid-columns), [col-start] 1fr);
grid-template-areas:
". title title title title title title"
". subtitle subtitle subtitle subtitle subtitle . "
". content content content content . . "
". list list list . . . "
". . . . link link link ";
}
In order to make the variant of the component we would have to create the grid-template-areas for that component too.
We then need to tell each element of the component in what grid-area it should be placed within the grid.
.features__title { grid-area: title; }
.features__subtitle { grid-area: subtitle; }
.features__content { grid-area: content; }
.features__list { grid-area: list; }
.features__link { grid-area: link; }
See the Pen Design Systems and CSS Grid, 12 by Stuart Robson (@sturobson) on CodePen.
The other way would be to use the grid-column shorthand and the grid-column-start and grid-column-end we have used previously.
.features .features__title {
grid-column: col-start 2 / span 6;
}
.features .features__subtitle {
grid-column: col-start 2 / span 5;
}
.features .features__content {
grid-column: col-start 2 / span 4;
}
.features .features__list {
grid-column: col-start 2 / span 4;
}
.features .features__link {
grid-column: col-start 5 / span 3;
}
For the variant of the component we can use the grid-column-start property as it will inherit the span defined in the grid-column shorthand.
.features:nth-of-type(even) .features__title {
grid-column-start: col-start 1;
}
.features:nth-of-type(even) .features__subtitle {
grid-column-start: col-start 1;
}
.features:nth-of-type(even) .features__content {
grid-column-start: col-start 3;
}
.features:nth-of-type(even) .features__list {
grid-column-start: col-start 3;
}
.features:nth-of-type(even) .features__link {
grid-column-start: col-start 1;
}
See the Pen Design Systems and CSS Grid, 14 by Stuart Robson (@sturobson) on CodePen.
I think, for now, we will go with using grid-column properties rather than grid-template-areas. The repetition needed for creating the variant feels too much where we can change the grid-column-start instead, keeping the components elements layout properties tied a little closer to the elements rather than the grid.
Some additional decisions
The current component library has existing styles for titles, subtitles, lists, paragraphs of text and calls to action. These are name-spaced so that they shouldn’t clash with any other components. Looking forward there will be a chance that other products adopt the component library, but they may bring their own styles for titles, subtitles, etc.
One way that we could write our code now for that near future possibility is to make sure our classes are working hard. Using class-attribute selectors we can target part of the class attributes that we know the elements in the component will have using *=.
.features [class*="title"] {
grid-column: col-start 2 / span 6;
}
.features [class*="subtitle"] {
grid-column: col-start 2 / span 5;
}
.features [class*="content"] {
grid-column: col-start 2 / span 4;
}
.features [class*="list"] {
grid-column: col-start 2 / span 4;
}
.features [class*="link"] {
grid-column: col-start 5 / span 3;
}
See the Pen Design Systems and CSS Grid, 15 by Stuart Robson (@sturobson) on CodePen.
Although the component we have created have a title, subtitle, paragraphs, a list, and a call to action there may be a time where one ore more of these is not required or available. One thing I found out is that if the element doesn’t exist then grid will not create space for it. This may be obvious, but it can be really helpful in making a nice malleable component.
We have only looked at columns, as existing components have their own spacing for the vertical rhythm of the page we don’t really want to have them take up equal space in the component and just take up the space as needed. We can do this by adding grid-auto-rows: min-content; to our .features. This is useful if you also need your component to take up a height that is more than the component itself.
The grid of the future
From prototyping this new grid and components in CSS Grid, I’ve found it a fantastic way to reimagine how we can create a layout or grid system for our sites. It gives us options to create the same layouts in differing ways that could suit a project and its needs.
It allows us to carry on – if we choose to – using a <div>-based grid but swapping out floats for CSS Grid or to tie it to our components so they have specific places to go depending on what component is being used. Or we could have several ‘grid components’ in our design system that we could use to layout various components throughout a page.
If you find yourself tasked with creating some new components for your design system try it. If you are starting from scratch I believe you really should start with CSS Grid for your layout.
It really feels like the possibilities are endless in terms of layout for the web.
Resources
Here are just a few resources I have pawed over these last few weeks whilst getting acquainted with CSS Grid.
A collection of CodePens from this article
Grid by Example from Rachel Andrew
A Complete Guide to CSS Grid on Codrops from Hui Jing Chen
Rachel Andrew’s Blog Archive tagged: cssgrid
CSS Grid Layout Examples
MDN’s CSS Grid Layout
A Complete Guide to Grid from CSS-Tricks
CSS Grid Layout Module Level 1 Specification |
2017 |
Stuart Robson |
stuartrobson |
2017-12-12T00:00:00+00:00 |
https://24ways.org/2017/design-systems-and-css-grid/ |
code |
| 246 |
Designing Your Site Like It’s 1998 |
It’s 20 years to the day since my wife and I started Stuff & Nonsense, our little studio and my outlet for creative ideas on the web. To celebrate this anniversary—and my fourteenth contribution to 24 ways— I’d like to explain how I would’ve developed a design for Planes, Trains and Automobiles, one of my favourite Christmas films.
My design for Planes, Trains and Automobiles is fixed at 800px wide.
Developing a <frameset> framework
I’ll start by using frames to set up the framework for this new website. Frames are individual pages—one for navigation, the other for my content—pulled together to form a frameset. Space is limited on lower-resolution screens, so by using frames I can ensure my navigation always remains visible. I can include any number of frames inside a <frameset> element.
I add two rows to my <frameset>; the first is for my navigation and is 50px tall, the second is for my content and will resize to fill any available space. As I don’t want frame borders or any space between my frames, I set frameborder and framespacing attributes to 0:
<frameset frameborder="0" framespacing="0" rows="50,*">
[…]
</frameset>
Next I add the source of my two frame documents. I don’t want people to be able to resize or scroll my navigation, so I add the noresize attribute to that frame:
<frameset frameborder="0" framespacing="0" rows="50,*">
<frame noresize scrolling="no" src="nav.html">
<frame src="content.html">
</frameset>
I do want links from my navigation to open in the content frame, so I give each <frame> a name so I can specify where I want links to open:
<frameset frameborder="0" framespacing="0" rows="50,*">
<frame name="navigation" noresize scrolling="no" src="nav.html">
<frame name="content" src="content.html">
</frameset>
The framework for this website is simple as it contains only two horizontal rows. Should I need a more complex layout, I can nest as many framesets—and as many individual documents—as I need:
<frameset rows="50,*">
<frame name="navigation">
<frameset cols="25%,*">
<frame name="sidebar">
<frame name="content">
</frameset>
</frameset>
Letterbox framesets were common way to deal with multiple screen sizes. In a letterbox, the central frameset had a fixed height and width, while the frames on the top, right, bottom, and left expanded to fill any remaining space.
Handling older browsers
Sadly not every browser supports frames, so I should send a helpful message to people who use older browsers asking them to upgrade. Happily, I can do that using noframes content:
<noframes>
<body>
<p>This page uses frames, but your browser doesn’t support them.
Please upgrade your browser.</p>
</body>
</noframes>
Forcing someone back into a frame
Sometimes, someone may follow a link to a page from a portal or search engine, or they might attempt to open it in a new window or tab. If that page properly belongs inside a <frameset>, people could easily miss out on other parts of a design. This short script will prevent this happening and because it’s vanilla Javascript, it doesn’t require a library such as jQuery:
<script type="text/javascript">
if (top == self) {
location = 'frameset.html';
}
</script>
Laying out my page
Before starting my layout, I add a few basic background and colour styles. I must include these attributes in every page on my website:
<body background="img/container.jpg" bgcolor="#fef7fb"
link="#245eab" alink="#245eab" vlink="#3c146e" text="#000000">
I want absolute control over how people experience my design and don’t want to allow it to stretch, so I first need a <table> which limits the width of my layout to 800px. The align attribute will keep this <table> in the centre of someone’s screen:
<table width="800" align="center">
<tr>
<td>[…]</td>
</tr>
</table>
Although they were developed for displaying tabular information, the cells and rows which make up the <table> element make it ideal for the precise implementation of a design. I need several tables—often nested inside each other—to implement my design. These include tables for a banner and three rows of content:
<table width="800" align="center">
<table>[…]</table>
<table>
<table>
<table>[…]</table>
</table>
</table>
<table>[…]</table>
<table>[…]</table>
</table>
The width of the first table—used for my banner—is fixed to match the logo it contains. As I don’t need borders, padding, or spacing between these cells, I use attributes to remove them:
<table border="0" cellpadding="0" cellspacing="0" width="587" align="center">
<tr>
<td><img src="logo.gif" border="0" width="587" alt="Logo"></td>
</tr>
</table>
The next table—which contains the largest image, introduction, and a call-to-action—is one of the most complex parts of my design, so I need to ensure its layout is pixel perfect. To do that I add an extra row at the top of this table and fill each of its cells with tiny transparent images:
<tr>
<td><img src="spacer.gif" width="593" height="1"></td>
<td><img src="spacer.gif" width="207" height="1"></td>
</tr>
The height and width of these “shims” or “spacers” is only 1px but they will stretch to any size without increasing their weight on the page. This makes them perfect for performant website development.
For the hero of this design, I splice up the large image into three separate files and apply each slice as a background to the table cells. I also match the height of those cells to the background images:
<tr>
<td background="slice-1.jpg" height="473"> </td>
<td background="slice-2.jpg" height="473">[…]</td>
</tr>
<tr>
<td background="slice-3.jpg" height="388"> </td>
</tr>
I use tables and spacer images throughout the rest of this design to lay out the various types of content with perfect precision. For example, to add a single-pixel border around my two columns of content, I first apply a blue background to an outer table along with 1px of cellspacing, then simply nest an inner table—this time with a white background—inside it:
<table border="0" cellpadding="1" cellspacing="0">
<tr>
<td>
<table bgcolor="#ffffff" border="0" cellpadding="0" cellspacing="0">
[…]
</table>
</td>
</tr>
</table>
Adding details
Tables are fabulous tools for laying out a page, but they’re also useful for implementing details on those pages. I can use a table to add a gradient background, rounded corners, and a shadow to the button which forms my “Buy the DVD” call-to-action. First, I splice my button graphic into three slices; two fixed-width rounded ends, plus a narrow gradient which stretches and makes this button responsive. Then, I add those images as backgrounds and use spacers to perfectly size my button:
<table border="0" cellpadding="0" cellspacing="0">
<tr>
<td background="btn-1.jpg" border="0" height="48" width="30"><img src="spacer.gif" width="30" height="1"></td>
<td background="btn-2.jpg" border="0" height="48">
<center>
<a href="" target="_blank"><b>Buy the DVD</b></a>
</center>
</td>
<td background="btn-3.jpg" border="0" height="48" width="30"><img src="spacer.gif" width="30" height="1"></td>
</tr>
</table>
I use those same elements to add details to headlines and lists too. Adding a “bullet” to each item in a list needs only two additional table cells, a circular graphic, and a spacer:
<table border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="10"><img src="li.gif" border="0" width="8" height="8"> </td>
<td><img src="spacer.gif" width="10" height="1"> </td>
<td>Directed by John Hughes</td>
</tr>
</table>
Implementing a typographic hierarchy
So far I’ve explained how to use frames, tables, and spacers to develop a layout for my content, but what about styling that content? I use <font> elements to change the typeface from the browser’s default to any font installed on someone’s device:
<font face="Arial">Planes, Trains and Automobiles is a comedy film […]</font>
To adjust the size of those fonts, I use the size attribute and a value between the smallest (1) and the largest (7) where 3 is the browser’s default. I use a size of 4 for this headline and 2 for the text which follows:
<font face="Arial" size="4"><b>Steve Martin</b></font>
<font face="Arial" size="2">An American actor, comedian, writer, producer, and musician.</font>
When I need to change the typeface, perhaps from a sans-serif like Arial to a serif like Times New Roman, I must change the value of the face attribute on every element on all pages on my website.
NB: I use as many <br> elements as needed to create space between headlines and paragraphs.
View the final result (and especially the source.)
My modern day design for Planes, Trains and Automobiles.
I can imagine many people reading this and thinking “This is terrible advice because we don’t develop websites like this in 2018.” That’s true.
We have the ability to embed any number of web fonts into our products and websites and have far more control over type features, leading, ligatures, and sizes:
font-variant-caps: titling-caps;
font-variant-ligatures: common-ligatures;
font-variant-numeric: oldstyle-nums;
Grid has simplified the implementation of even the most complex compound grid down to just a few lines of CSS:
body {
display: grid;
grid-template-columns: 3fr 1fr 2fr 2fr 1fr 3fr;
grid-template-rows: auto;
grid-column-gap: 2vw;
grid-row-gap: 1vh;
}
Flexbox has made it easy to develop flexible components such as navigation links:
nav ul { display: flex; }
nav li { flex: 1; }
Just one line of CSS can create multiple columns of fluid type:
main { column-width: 12em; }
CSS Shapes enable text to flow around irregular shapes including polygons:
[src*="main-img"] {
float: left;
shape-outside: polygon(…);
}
Today, we wouldn’t dream of using images and a table to add a gradient, rounded corners, and a shadow to a button or link, preferring instead:
.btn {
background: linear-gradient(#8B1212, #DD3A3C);
border-radius: 1em;
box-shadow: 0 2px 4px 0 rgba(0,0,0,0.50), inset 0 -1px 1px 0 rgba(0,0,0,0.50);
}
CSS Custom Properties, feature and media queries, filters, pseudo-elements, and SVG; the list of advances in HTML, CSS, and other technologies goes on. So does our understanding of how best to use them by separating content, structure, presentation, and behaviour. As 2018 draws to a close, we’re certain we know how to design and develop products and websites better than we did at the end of 1998.
Strange as it might seem looking back, in 1998 we were also certain our techniques and technologies were the best for the job. That’s why it’s dangerous to believe with absolute certainty that the frameworks and tools we increasingly rely on today—tools like Bootstrap, Bower, and Brunch, Grunt, Gulp, Node, Require, React, and Sass—will be any more relevant in the future than <font> elements, frames, layout tables, and spacer images are today.
I have no prediction for what the web will be like twenty years from now. However, I want to believe we’ll build on what we’ve learned during these past two decades about the importance of accessibility, flexibility, and usability, and that the mistakes we made while infatuated by technologies won’t be repeated.
Head over to my website if you’d like to read about how I’d implement my design for ‘Planes, Trains and Automobiles’ today. |
2018 |
Andy Clarke |
andyclarke |
2018-12-23T00:00:00+00:00 |
https://24ways.org/2018/designing-your-site-like-its-1998/ |
code |
| 231 |
Designing for iOS: Life Beyond Media Queries |
Although not a new phenomenon, media queries seem to be getting a lot attention online recently and for the right reasons too – it’s great to be able to adapt a design with just a few lines of CSS – but many people are relying only on them to create an iPhone-specific version of their website.
I was pleased to hear at FOWD NYC a few weeks ago that both myself and Aral Balkan share the same views on why media queries aren’t always going to be the best solution for mobile. Both of us specialise in iPhone design ourselves and we opt for a different approach to media queries. The trouble is, regardless of what you have carefully selected to be display:none; in your CSS, the iPhone still loads everything in the background; all that large imagery for your full scale website also takes up valuable mobile bandwidth and time.
You can greatly increase the speed of your website by creating a specific site tailored to mobile users with just a few handy pointers – media queries, in some instances, might be perfectly suitable but, in others, here’s what you can do.
Redirect your iPhone/iPod Touch users
To detect whether someone is viewing your site on an iPhone or iPod Touch, you can either use JavaScript or PHP.
The JavaScript
if((navigator.userAgent.match(/iPhone/i)) || (navigator.userAgent.match(/iPod/i))) {
if (document.cookie.indexOf("iphone_redirect=false") == -1) window.location = "http://mobile.yoursitehere.com";
}
The PHP
if(strstr($_SERVER['HTTP_USER_AGENT'],'iPhone') || strstr($_SERVER['HTTP_USER_AGENT'],'iPod'))
{
header('Location: http://mobile.yoursitehere.com');
exit();
}
Both of these methods redirect the user to a site that you have made specifically for the iPhone. At this point, be sure to provide a link to the full version of the website, in case the user wishes to view this and not be thrown into an experience they didn’t want, with no way back.
Tailoring your site
So, now you’ve got 320 × 480 pixels of screen to play with – and to create a style sheet for, just as you would for any other site you build. There are a few other bits and pieces that you can add to your code to create a site that feels more like a fully immersive iPhone app rather than a website.
Retina display
When building your website specifically tailored to the iPhone, you might like to go one step further and create a specific style sheet for iPhone 4’s Retina display. Because there are four times as many pixels on the iPhone 4 (640 × 960 pixels), you’ll find specifics such as text shadows and borders will have to be increased.
<link rel="stylesheet"
media="only screen and (-webkit-min-device-pixel-ratio: 2)"
type="text/css" href="../iphone4.css" />
(Credit to Thomas Maier)
Prevent user scaling
This declaration, added into the <head>, stops the user being able to pinch-zoom in and out of your design, which is perfect if you are designing to the exact pixel measurements of the iPhone screen.
<meta name="viewport"
content="width=device-width; initial-scale=1.0; maximum-scale=1.0;">
Designing for orientation
As iPhones aren’t static devices, you’ll also need to provide a style sheet for horizontal orientation. We can do this by inserting some JavaScript into the <head> as follows:
<script type="text/javascript">
function orient() {
switch(window.orientation) {
case 0:
document.getElementById("orient_css").href = "css/iphone_portrait.css";
break;
case -90:
document.getElementById("orient_css").href = "css/iphone_landscape.css";
break;
case 90:
document.getElementById("orient_css").href = "css/iphone_landscape.css";
break;
}
}
window.onload = orient();
</script>
You can also specify orientation styles using media queries. This is absolutely fine, as by this point you’ll already be working with mobile-specific graphics and have little need to set a lot of things to display:none;
<link rel="stylesheet"
media="only screen and (max-device-width: 480px)" href="/iphone.css">
<link rel="stylesheet"
media="only screen and (orientation: portrait)" href="/portrait.css">
<link rel="stylesheet"
media="only screen and (orientation: landscape)” href="/landscape.css">
Remove the address and status bars, top and bottom
To give you more room on-screen and to make your site feel more like an immersive web app, you can place the following declaration into the <head> of your document’s code to remove the address and status bars at the top and bottom of the screen.
<meta name="apple-mobile-web-app-capable" content="yes" />
Making the most of inbuilt functions
Similar to mailto: e-mail links, the iPhone also supports another two handy URI schemes which are great for enhancing contact details. When tapped, the following links will automatically bring up the appropriate call or text interface:
<a href="tel:01234567890">Call us</a>
<a href="sms:01234567890">Text us</a>
iPhone-specific Web Clip icon
Although I believe them to be fundamentally flawed, since they rely on the user bookmarking your site, iPhone Web Clip icons are still a nice touch. You need just two declarations, again in the <head> of your document:
<link rel="apple-touch-icon" href="icons/regular_icon.png" />
<link rel="apple-touch-icon" sizes="114x114" href="icons/retina_icon.png" />
For iPhone 4 you’ll need to create a 114 × 114 pixels icon; for a non-Retina display, a 57 × 57 pixels icon will do the trick.
Precomposed
Apple adds its standard gloss ‘moon’ over the top of any icon. If you feel this might be too much for your particular icon and would prefer a matte finish, you can add precomposed to the end of the apple-touch-icon declaration to remove the standard gloss.
<link rel="apple-touch-icon-precomposed" href="/images/touch-icon.png" />
Wrapping up
Media queries definitely have their uses. They make it easy to build a custom experience for your visitor, regardless of their browser’s size. For more complex sites, however, or where you have lots of imagery and other content that isn’t necessary on the mobile version, you can now use these other methods to help you out. Remember, they are purely for presentation and not optimisation; for busy people on the go, optimisation and faster-running mobile experiences can only be a good thing.
Have a wonderful Christmas fellow Webbies! |
2010 |
Sarah Parmenter |
sarahparmenter |
2010-12-17T00:00:00+00:00 |
https://24ways.org/2010/life-beyond-media-queries/ |
code |
| 256 |
Develop Your Naturalist Superpowers with Observable Notebooks and iNaturalist |
We’re going to level up your knowledge of what animals you might see in an area at a particular time of year - a skill every naturalist* strives for - using technology! Using iNaturalist and Observable Notebooks we’re going to prototype seasonality graphs for particular species in an area, and automatically create a guide to what animals you might see in each month.
*(a Naturalist is someone who likes learning about nature, not someone who’s a fan of being naked, that’s a ‘Naturist’… different thing!)
Looking for critters in rocky intertidal habitats
One of my favourite things to do is going rockpooling, or as we call it over here in California, ‘tidepooling’. Amounting to the same thing, it’s going to a beach that has rocks where the tide covers then uncovers little pools of water at different times of the day. All sorts of fun creatures and life can be found in this ‘rocky intertidal habitat’
A particularly exciting creature that lives here is the Nudibranch, a type of super colourful ‘sea slug’. There are over 3000 species of Nudibranch worldwide. (The word “nudibranch” comes from the Latin nudus, naked, and the Greek βρανχια / brankhia, gills.)
They are however quite tricky to find! Even though they are often brightly coloured and interestingly shaped, some of them are very small, and in our part of the world in the Bay Area in California their appearance in our rockpools is seasonal. We see them more often in Summer months, despite the not-as-low tides as in our Winter and Spring seasons.
My favourite place to go tidepooling here is Pillar Point in Half Moon bay (at other times of the year more famously known for the surf competition ‘Mavericks’). The rockpools there are rich in species diversity, of varied types and water-coverage habitat zones as well as being relatively accessible.
I was rockpooling at Pillar Point recently with my parents and we talked to a lady who remarked that she hadn’t seen any Nudibranchs on her visit this time. I realised that having an idea of what species to find where, and at what time of year is one of the many superpower goals of every budding Naturalist.
Using technology and the croudsourced species observations of the iNaturalist community we can shortcut our way to this superpower!
Finding nearby animals with iNaturalist
We’re going to be getting our information about what animals you can see in Pillar Point using iNaturalist. iNaturalist is a really fun platform that helps connect people to nature and report their findings of life in the outdoors. It is also a community of nature-loving people who help each other identify and confirm those observations. iNaturalist is a project run as a joint initiative by the California Academy of Sciences and the National Geographic Society.
I’ve been using iNaturalist for over two years to record and identify plants and animals that I’ve found in the outdoors. I use their iPhone app to upload my pictures, which then uses machine learning algorithms to make an initial guess at what it is I’ve seen. The community is really active, and I often find someone else has verified or updated my species guess pretty soon after posting.
This process is great because once an observation has been identified by at least two people it becomes ‘verified’ and is considered research grade. Research grade observations get exported and used by scientists, as well as being indexed by the Global Biodiversity Information Facility, GBIF.
iNaturalist has a great API and API explorer, which makes interacting and prototyping using iNaturalist data really fun. For example, if you go to the API explorer and expand the Observations : Search and fetch section and then the GET /observations API, you get a selection of input boxes that allow you to play with options that you can then pass to the API when you click the ‘Try it out’ button.
You’ll then get a URL that looks a bit like
https://api.inaturalist.org/v1/observations?captive=false &geo=true&verifiable=true&taxon_id=47113&lat=37.495461&lng=-122.499584 &radius=5&order=desc&order_by=created_at
which you can call and interrrogate using a programming language of your choice.
If you would like to see an all-JavaScript application that uses the iNaturalist API, take a look at OwlsNearMe.com which Simon and I built one weekend earlier this year. It gets your location and shows you all iNaturalist observations of owls near you and lists which species you are likely to see (not adjusted for season).
Rapid development using Observable Notebooks
We’re going to be using Observable Notebooks to prototype our examples, pulling data down from iNaturalist. I really like using visual notebooks like Observable, they are great for learning and building things quickly. You may be familiar with Jupyter notebooks for Python which is similar but takes a bit of setup to get going - I often use these for prototyping too. Observable is amazing for querying and visualising data with JavaScript and since it is a hosted product it doesn’t require any setup at all.
You can follow along and play with this example on my Observable notebook. If you create an account there you can fork my notebook and create your own version of this example.
Each ‘notebook’ consists of a page with a column of ‘cells’, similar to what you get in a spreadsheet. A cell can contain Markdown text or JavaScript code and the output of evaluating the cell appears above the code that generated it. There are lots of tutorials out there on Observable Notebooks, I like this code introduction one from Observable (and D3) creator Mike Bostock.
Developing your Naturalist superpowers
If you have an idea of what plants and critters you might see in a place at the time you visit, you can hone in on what you want to study and train your Naturalist eye to better identify the life around you.
For our example, we care about wildlife we can see at Pillar Point, so we need a way of letting the iNaturalist API know which area we are interested in.
We could use a latitide, longitude and radius for this, but a rectangular bounding box is a better shape for the reef. We can use this tool to draw the area we want to search within: boundingbox.klokantech.com
The tool lets you export the bounding box in several forms using the dropdown at the bottom left under the map givese We are going to use the ‘DublinCore’ format as it’s closest to the format needed by the iNaturalist API.
westlimit=-122.50542; southlimit=37.492805; eastlimit=-122.492738; northlimit=37.499811
A quick map primer:
The higher the latitude the more north it is
The lower the latitude the more south it is
Latitude 0 = the equator
The higher the longitude the more east it is of Greenwich
The lower the longitude the more west it is of Greenwich
Longitude 0 = Greenwich
In the iNaturalst API we want to use the parameters nelat, nelng, swlat, swlng to create a query that looks inside a bounding box of Pillar Point near Half Moon Bay in California:
nelat = highest latitude = north limit = 37.499811
nelng = highest longitude = east limit = -122.492738
swlat = smallest latitude = south limit = 37.492805
swlng = smallest longitude = west limit = 122.50542
As API parameters these look like this:
?nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=122.50542
These parameters in this format can be used for most of the iNaturalist API methods.
Nudibranch seasonality in Pillar Point
We can use the iNaturalist observation_histogram API to get a count of Nudibranch observations per week-of-year across all time and within our Pillar Point bounding box.
In addition to the geographic parameters that we just worked out, we are also sending the taxon_id of 47113, which is iNaturalists internal number associated with the Nudibranch taxon. By using this we can get all species which are under the parent ‘Order Nudibranchia’.
Another useful piece of naturalist knowledge is understanding the biological classification scheme of Taxanomic Rank - roughly, when a species has a Latin name of two words eg ‘Glaucus Atlanticus’ the first Latin word is the ‘Genus’ like a family name ‘Glaucus’, and the second word identifies that particular species, like a given name ‘Atlanticus’.
The two Latin words together indicate a specific species, the term we use colloquially to refer to a type of animal often differs wildly region to region, and sometimes the same common name in two countries can refer to two different species. The common names for the Glaucus Atlanticus (which incidentally is my favourite sea slug) include: sea swallow, blue angel, blue glaucus, blue dragon, blue sea slug and blue ocean slug! Because this gets super confusing, Scientists like using this Latin name format instead.
The following piece of code asks the iNaturalist Histogram API to return per-week counts for verified observations of Nudibranchs within our Pillar Point bounding box:
pillar_point_counts_per_week = fetch(
"https://api.inaturalist.org/v1/observations/histogram?taxon_id=47113&nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=-122.50542&date_field=observed&interval=week_of_year&verifiable=true"
).then(response => {
return response.json();
})
Our next step is to take this data and draw a graph! We’ll be using Vega-Lite for this, which is a fab JavaScript graphing libary that is also easy and fun to use with Observable Notebooks.
(Here is a great tutorial on exploring data and drawing graphs with Observable and Vega-Lite)
The iNaturalist API returns data that looks like this:
{
"total_results": 53,
"page": 1,
"per_page": 53,
"results": {
"week_of_year": {
"1": 136,
"2": 20,
"3": 150,
"4": 65,
"5": 186,
"6": 74,
"7": 47,
"8": 87,
"9": 64,
"10": 56,
But for our Vega-Lite graph we need data that looks like this:
[{
"week": "01",
"value": 136
}, {
"week": "02",
"value": 20
}, ...]
We can convert what we get back from the API to the second format using a loop that iterates over the object keys:
objects_to_plot = {
let objects = [];
Object.keys(pillar_point_counts_per_week.results.week_of_year).map(function(week_index) {
objects.push({
week: `Wk ${week_index.toString()}`,
observations: pillar_point_counts_per_week.results.week_of_year[week_index]
});
})
return objects;
}
We can then plug this into Vega-Lite to draw us a graph:
vegalite({
data: {values: objects_to_plot},
mark: "bar",
encoding: {
x: {field: "week", type: "nominal", sort: null},
y: {field: "observations", type: "quantitative"}
},
width: width * 0.9
})
It’s worth noting that we have a lot of observations of Nudibranchs particularly at Pillar Point due in no small part to the intertidal monitoring research that Alison Young and Rebecca Johnson facilitate for the California Achademy of Sciences.
So, what if we want to look for the seasonality of observations of a particular species of adorable sea slug? We want our interface to have a select box with a list of all the species you might find at any time of year. We can do this using the species_counts API to create us an object with the iNaturalist species ID and common & Latin names.
pillar_point_nudibranches = {
let api_results = await fetch(
"https://api.inaturalist.org/v1/observations/species_counts?taxon_id=47113&nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=-122.50542&date_field=observed&verifiable=true"
).then(r => r.json())
let species_list = api_results.results.map(i => ({
value: i.taxon.id,
label: `${i.taxon.preferred_common_name} (${i.taxon.name})`
}));
return species_list
}
We can create an interactive select box by importing code from Jeremy Ashkanas’ Observable Notebook: add import {select} from "@jashkenas/inputs" to a cell anywhere in our notebook. Observable is magic: like a spreadsheet, the order of the cells doesn’t matter - if one cell is referenced by any other cell then when that cell updates all the other cells refresh themselves. You can also import and reference one notebook from another!
viewof select_species = select({
title: "Which Nudibranch do you want to see seasonality for?",
options: [{value: "", label: "All the Nudibranchs!"}, ...pillar_point_nudibranches],
value: ""
})
Then we go back to our old favourite, the histogram API just like before, only this time we are calling it with the value created by our select box ${select_species} as taxon_id instead of the number 47113.
pillar_point_counts_per_month_per_species = fetch(
`https://api.inaturalist.org/v1/observations/histogram?taxon_id=${select_species}&nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=-122.50542&date_field=observed&interval=month_of_year&verifiable=true`
).then(r => r.json())
Now for the fun graph bit! As we did before, we re-format the result of the API into a format compatible with Vega-Lite:
objects_to_plot_species_month = {
let objects = [];
Object.keys(pillar_point_counts_per_month_per_species.results.month_of_year).map(function(month_index) {
objects.push({
month: (new Date(2018, (month_index - 1), 1)).toLocaleString("en", {month: "long"}),
observations: pillar_point_counts_per_month_per_species.results.month_of_year[month_index]
});
})
return objects;
}
(Note that in the above code we are creating a date object with our specific month in, and using toLocalString() to get the longer English name for the month. Because the JavaScript Date object counts January as 0, we use month_index -1 to get the correct month)
And we draw the graph as we did before, only now if you interact with the select box in Observable the graph will dynamically update!
vegalite({
data: {values: objects_to_plot_species_month},
mark: "bar",
encoding: {
x: {field: "month", type: "nominal", sort:null},
y: {field: "observations", type: "quantitative"}
},
width: width * 0.9
})
Now we can see when is the best time of year to plan to go tidepooling in Pillar Point if we want to find a specific species of Nudibranch.
This tool is great for planning when we to go rockpooling at Pillar Point, but what about if you are going this month and want to pre-train your eye with what to look for in order to impress your friends with your knowledge of Nudibranchs?
Well… we can create ourselves a dynamic guide that you can with a list of the species, their photo, name and how many times they have been observed in that month of the year!
Our select box this time looks as follows, simpler than before but assigning the month value to the variable selected_month.
viewof selected_month = select({
title: "When do you want to see Nudibranchs?",
options: [
{ label: "Whenever", value: "" },
{ label: "January", value: "1" },
{ label: "February", value: "2" },
{ label: "March", value: "3" },
{ label: "April", value: "4" },
{ label: "May", value: "5" },
{ label: "June", value: "6" },
{ label: "July", value: "7" },
{ label: "August", value: "8" },
{ label: "September", value: "9" },
{ label: "October", value: "10" },
{ label: "November", value: "11" },
{ label: "December", value: "12" },
],
value: ""
})
We then can use the species_counts API to get all the relevant information about which species we can see in month=${selected_month}. We’ll be able to reference this response object and its values later with the variable we just created, eg: all_species_data.results[0].taxon.name.
all_species_data = fetch(
`https://api.inaturalist.org/v1/observations/species_counts?taxon_id=47113&month=${selected_month}&nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=-122.50542&verifiable=true`
).then(r => r.json())
You can render HTML directly in a notebook cell using Observable’s html tagged template literal:
<style>
.collection { margin-top: 2em }
.collection .species { display: inline-block; width: 9em; margin-bottom: 2em; }
.collection .species-name { font-size: 1em; margin: 0; padding: 0 }
.collection .species-count { margin: 0 0 0.3em 0; padding: 0; font-size: 0.75em; color: #999; font-style: italic; }
.collection img { display: block; width: 100% }
.collection select { font-size: 1.5em; }
</style>
<h2>If you go to Pillar Point ${
{"": "",
"1":"in January",
"2":"in Febrary",
"3":"in March",
"4":"in April",
"5":"in May",
"6":"in June",
"7":"in July",
"8":"in August",
"9":"in September",
"10":"in October",
"11":"in November",
"12":"in December",
}[selected_month]
} you might see…</h2>
<div class="collection">
${all_species_data.results.map(s => `<div class="species"><h3 class="species-name">${s.taxon.name}</h3>
<p class="species-count">Seen ${s.count} times</p>
<img src="${s.taxon.default_photo.medium_url}"></div>
`)}
</div>
These few lines of HTML are all you need to get this exciting dynamic guide to what Nudibranchs you will see in each month!
Play with it yourself in this Observable Notebook.
Conclusion
I hope by playing with these examples you have an idea of how powerful it can be to prototype using Observable Notebooks and how you can use the incredible crowdsourced community data and APIs from iNaturalist to augment your naturalist skills and impress your friends with your new ‘knowledge of nature’ superpower.
Lastly I strongly encourage you to get outside on a low tide to explore your local rocky intertidal habitat, and all the amazing critters that live there.
Here is a great introduction video to tidepooling / rockpooling, by Rebecca Johnson and Alison Young from the California Academy of Sciences. |
2018 |
Natalie Downe |
nataliedowne |
2018-12-18T00:00:00+00:00 |
https://24ways.org/2018/observable-notebooks-and-inaturalist/ |
code |
| 89 |
Direction, Distance and Destinations |
With all these new smartphones in the hands of lost and confused owners, we need a better way to represent distances and directions to destinations. The immediate examples that jump to mind are augmented reality apps which let you see another world through your phone’s camera. While this is interesting, there is a simpler way: letting people know how far away they are and if they are getting warmer or colder.
In the app world, you can easily tap into the phone’s array of sensors such as the GPS and compass, but what people rarely know is that you can do the same with HTML. The native versus web app debate will never subside, but at least we can show you how to replicate some of the functionality progressively in HTML and JavaScript.
In this tutorial, we’ll walk through how to create a simple webpage listing distances and directions of a few popular locations around the world. We’ll use JavaScript to access the device’s geolocation API and also attempt to access the compass to get a heading. Both of these APIs are documented, to be included in the W3C geolocation API specification, and can be used on both desktop and mobile devices today.
To get started, we need a list of a few locations around the world. I have chosen the highest mountain peak on each continent so you can see a diverse set of distances and directions.
Mountain
°Latitude
°Longitude
Kilimanjaro
-3.075833
37.353333
Vinson Massif
-78.525483
-85.617147
Puncak Jaya
-4.078889
137.158333
Everest
27.988056
86.925278
Elbrus
43.355
42.439167
Mount McKinley
63.0695
-151.0074
Aconcagua
-32.653431
-70.011083
Source: Wikipedia
We can put those into an HTML list to be styled and accessed by JavaScript to create some distance and directions calculations.
The next thing we need to do is check to see if the browser and operating system have geolocation support. To do this we test to see if the function is available or not using a single JavaScript if statement.
<script>
// If this is true, then the method is supported and we can try to access the location
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(geo_success, geo_error);
}
</script>
The if statement will be false if geolocation support is not present, and then it is up to you to do something else instead as a fallback. For this example, we’ll do nothing since our page should work as is and only get progressively better if more functionality is available.
The if statement will be true if there is support and therefore will continue inside the curly brackets to try to get the location. This should prompt the reader to accept or deny the request to get their location. If they say no, the second function callback is processed, in this case a function called geo_error; whereas if the location is available, it fires the geo_success function callback.
The function geo_error(){ } isn’t that exciting. You can handle this in any way you see fit. The success function is more interesting. We get a position object passed into the function which contains a series of exciting attributes, namely the latitude and longitude of the device’s current location.
function geo_success(position){
gLat = position.coords.latitude;
gLon = position.coords.longitude;
}
Now, in the variables gLat and gLon we have the user’s approximate geographical position. We can use this information to start to calculate some distances between where they are and all the destinations.
At the time of writing, you can also get position.coords.heading, but on Windows and iOS devices this returned NULL. In the future, if and when this is supported, this is also where you can easily grab the compass information.
Inside the geo_success function, we want to loop through the HTML to get all of the mountain peaks’ latitudes and longitudes and compute the distance.
...
$('.geo').each(function(){
// Get the lat/lon from the HTML
tLat = $(this).find('.lat').html()
tLon = $(this).find('.lon').html()
// compute the distances between the current location and this points location
dist = distance(tLat,tLon,gLat,gLon);
// set the return values into something useful
d = parseInt(dist[0]*10)/10;
a = parseFloat(dist[1]);
// display the value in the HTML and style the arrow
$(this).find('.distance').html(d+' km away');
$(this).find('.direction').css('-webkit-transform','rotate(-' + a + 'deg)');
// store the arc for later use if compass is available
$(this).attr('data-arc',a);
}
In the variable d we have the distance between the current location and the location of the mountain peak based on the Haversine Formula. The variable a is the arc, which has a value from 0 to 359.99. This will be useful later if we have compass support. Given these two values we have a distance and a heading to style the HTML.
The next thing we want to do is check to see if the device has a compass and then get access to the the current heading. As we’ll see, there are several ways to do this, some of which work on certain devices but not others. The W3C geolocation spec says that, along with the coordinates, there are several other attributes: accuracy; altitude; and heading. Heading is the direction to true north, which is different than magnetic north! WebKit and Windows return NULL for the heading value, but WebKit has an experimental method to fetch the heading. If you get into accessing these sensors, you’ll have to try to catch a few of these methods to finally get a value. Assuming you do, we can move on to the more interesting display opportunities.
In an ideal world, this would succeed and set a variable we’ll call compassHeading to get a value between 0 and 359.99 degrees. Now we know which direction north is, we also know the direction relative to north of the path to our destination, so we can can subtract the two values to get an arrow to display on the screen. But we’re not finished yet: we also need to get the device’s orientation (landscape or portrait) and subtract the correct amount from the angle for the arrow. Once we have a value, we can use CSS to rotate the arrow the correct number of degrees.
-webkit-transform: rotate(-180deg)
Not all devices support a standard way to access compass information, so in the meantime we need to use a work around. On iOS, you can use the experimental event method e.webkitCompassHeading. We want the compass to update in real time as the device is moved around, so we’ll put this inside an event listener.
window.addEventListener('deviceorientation', function(e) {
// Loop through all the locations on the page
$('.geo').each(function(){
// get the arc value from north we computed and stored earlier
destination_arc = parseInt($(this).attr('data-arc'))
compassHeading = e.webkitCompassHeading + window.orientation + destination_arc;
// find the arrow element and rotate it accordingly
$(this).find('.direction').css('-webkit-transform','rotate(-' + compassHeading + 'deg)');
}
}
As the device is rotated, the compass arrow will constantly be updated. If you want to see an example, you can have a look at this page which shows the distances to all the peaks on each continent.
With progressive enhancement, we slowly layer on additional functionality as we go. The reader will first see the list of locations with a latitude and longitude. If the device is capable and permissions allow, it will then compute the distance. If a compass is available, with the correct permissions it will then add the final layer which is direction.
You should consider this code a stub for your projects. If you are making a hyperlocal webpage with restaurant locations, for example, then consider adding these features. Knowing not only how far away a place is, but also the direction can be hugely important, and since the compass is always active, it acts as a guide to the location.
Future developments
Improvements to this could include setting a timer and recalling the navigator.geolocation.getCurrentPosition() function and updating the distances. I chose very distant mountains so kilometres made sense, but you can divide again by 1,000 to convert to metres if you are dealing with much nearer places. Walking or driving would change the distances so the ability to refresh would be important.
It is outside the scope of this article, but if you manage to get this HTML to work offline, then you can make a nice web app which sits on your devices’ homescreens and works even without an internet connection. This could be ideal for travellers in an unknown city looking for your destination. Just with offline storage, base64 encoding and data URIs, it is possible to embed plenty of design and functionality into a small offline webpage.
Now you know how to use JavaScript to look up a destination’s location and figure out the distance and direction – never get lost again. |
2012 |
Brian Suda |
briansuda |
2012-12-19T00:00:00+00:00 |
https://24ways.org/2012/direction-distance-and-destinations/ |
code |
| 288 |
Displaying Icons with Fonts and Data- Attributes |
Traditionally, bitmap formats such as PNG have been the standard way of delivering iconography on websites. They’re quick and easy, and it also ensures they’re as pixel crisp as possible. Bitmaps have two drawbacks, however: multiple HTTP requests, affecting the page’s loading performance; and a lack of scalability, noticeable when the page is zoomed or viewed on a screen with a high pixel density, such as the iPhone 4 and 4S.
The requests problem is normally solved by using CSS sprites, combining the icon set into one (physically) large image file and showing the relevant portion via background-position. While this works well, it can get a bit fiddly to specify all the positions. In particular, scalability is still an issue. A vector-based format such as SVG sounds ideal to solve this, but browser support is still patchy.
The rise and adoption of web fonts have given us another alternative. By their very nature, they’re not only scalable, but resolution-independent too. No need to specify higher resolution graphics for high resolution screens!
That’s not all though:
Browser support: Unlike a lot of new shiny techniques, they have been supported by Internet Explorer since version 4, and, of course, by all modern browsers. We do need several different formats, however!
Design on the fly: The font contains the basic graphic, which can then be coloured easily with CSS – changing colours for themes or :hover and :focus styles is done with one line of CSS, rather than requiring a new graphic. You can also use CSS3 properties such as text-shadow to add further effects. Using -webkit-background-clip: text;, it’s possible to use gradient and inset shadow effects, although this creates a bitmap mask which spoils the scalability.
Small file size: specially designed icon fonts, such as Drew Wilson’s Pictos font, can be as little as 12Kb for the .woff font. This is because they contain fewer characters than a fully fledged font. You can see Pictos being used in the wild on sites like Garrett Murray’s Maniacal Rage.
As with all formats though, it’s not without its disadvantages:
Icons can only be rendered in monochrome or with a gradient fill in browsers that are capable of rendering CSS3 gradients. Specific parts of the icon can’t be a different colour.
It’s only appropriate when there is an accompanying text to provide meaning. This can be alleviated by wrapping the text label in a tag (I like to use <b> rather than <span>, due to the fact that it’s smaller and isn’ t being used elsewhere) and then hiding it from view with text-indent:-999em.
Creating an icon font can be a complex and time-consuming process. While font editors can carry out hinting automatically, the best results are achieved manually.
Unless you’re adept at creating your own fonts, you’re restricted to what is available in the font. However, fonts like Pictos will cover the most common needs, and icons are most effective when they’re using familiar conventions.
The main complaint about using fonts for icons is that it can mean adding a meaningless character to our markup. The good news is that we can overcome this by using one of two methods – CSS generated content or the data-icon attribute – in combination with the :before and :after pseudo-selectors, to keep our markup minimal and meaningful.
Our simple markup looks like this:
<a href="/basket" class="icon basket">View Basket</a>
Note the multiple class attributes. Next, we’ll import the Pictos font using the @font-face web fonts property in CSS:
@font-face {
font-family: 'Pictos';
src: url('pictos-web.eot');
src: local('☺'),
url('pictos-web.woff') format('woff'),
url('pictos-web.ttf') format('truetype'),
url('pictos-web.svg#webfontIyfZbseF') format('svg');
}
This rather complicated looking set of rules is (at the time of writing) the most bulletproof way of ensuring as many browsers as possible load the font we want. We’ll now use the content property applied to the :before pseudo-class selector to generate our icon. Once again, we’ll use those multiple class attribute values to set common icon styles, then specific styles for .basket. This helps us avoid repeating styles:
.icon {
font-family: 'Pictos';
font-size: 22px:
}
.basket:before {
content: "$";
}
What does the :before pseudo-class do? It generates the dollar character in a browser, even when it’s not present in the markup. Using the generated content approach means our markup stays simple, but we’ll need a new line of CSS, defining what letter to apply to each class attribute for every icon we add.
data-icon is a new alternative approach that uses the HTML5 data- attribute in combination with CSS attribute selectors. This new attribute lets us add our own metadata to elements, as long as its prefixed by data- and doesn’t contain any uppercase letters. In this case, we want to use it to provide the letter value for the icon. Look closely at this markup and you’ll see the data-icon attribute.
<a href="/basket" class="icon" data-icon="$">View Basket</a>
We could add others, in fact as many as we like.
<a href="/" class="icon" data-icon="k">Favourites</a>
<a href="/" class="icon" data-icon="t">History</a>
<a href="/" class="icon" data-icon="@">Location</a>
Then, we need just one CSS attribute selector to style all our icons in one go:
.icon:before {
content: attr(data-icon);
/* Insert your fancy colours here */
}
By placing our custom attribute data-icon in the selector in this way, we can enable CSS to read the value of that attribute and display it before the element (in this case, the anchor tag). It saves writing a lot of CSS rules. I can imagine that some may not like the extra attribute, but it does keep it out of the actual content – generated or not.
This could be used for all manner of tasks, including a media player and large simple illustrations. See the demo for live examples. Go ahead and zoom the page, and the icons will be crisp, with the exception of the examples that use -webkit-background-clip: text as mentioned earlier.
Finally, it’s worth pointing out that with both generated content and the data-icon method, the letter will be announced to people using screen readers. For example, with the shopping basket icon above, the reader will say “dollar sign view basket”. As accessibility issues go, it’s not exactly the worst, but could be confusing. You would need to decide whether this method is appropriate for the audience. Despite the disadvantages, icon fonts have huge potential. |
2011 |
Jon Hicks |
jonhicks |
2011-12-12T00:00:00+00:00 |
https://24ways.org/2011/displaying-icons-with-fonts-and-data-attributes/ |
code |
| 188 |
Don't Lose Your :focus |
For many web designers, accessibility conjures up images of blind users with screenreaders, and the difficulties in making sites accessible to this particular audience. Of course, accessibility covers a wide range of situations that go beyond the extreme example of screenreader users. And while it’s true that making a complex site accessible can often be a daunting prospect, there are also many small things that don’t take anything more than a bit of judicious planning, are very easy to test (without having to buy expensive assistive technology), and can make all the difference to certain user groups.
In this short article we’ll focus on keyboard accessibility and how careless use of CSS can potentially make your sites completely unusable.
Keyboard Access
Users who for whatever reason can’t use a mouse will employ a keyboard (or keyboard-like custom interface) to navigate around web pages. By default, they will use TAB and SHIFT + TAB to move from one focusable element (links, form controls and area) of a page to the next.
Note: in OS X, you’ll first need to turn on full keyboard access under System Preferences > Keyboard and Mouse > Keyboard Shortcuts. Safari under Windows needs to have the option Press Tab to highlight each item on a webpage in Preferences > Advanced enabled. Opera is the odd one out, as it has a variety of keyboard navigation options – the most relevant here being spatial navigation via Shift+Down, Shift+Up, Shift+Left, and Shift+Right).
But I Don’t Like Your Dotted Lines…
To show users where they are within a page, browsers place an outline around the element that currently has focus. The “problem” with these default outlines is that some browsers (Internet Explorer and Firefox) also display them when a user clicks on a focusable element with the mouse. Particularly on sites that make extensive use of image replacement on links with “off left” techniques this can create very unsightly outlines that stretch from the replaced element all the way to the left edge of the browser.
Outline bleeding off to the left (image-replacement example from carsonified.com)
There is a trivial workaround to prevent outlines from “spilling over” by adding a simple overflow:hidden, which keeps the outline in check around the clickable portion of the image-replaced element itself.
Outline tamed with overflow:hidden
But for many designers, even this is not enough. As a final solution, many actively suppress outlines altogether in their stylesheets. Controversially, even Eric Meyer’s popular reset.css – an otherwise excellent set of styles that levels the playing field of varying browser defaults – suppresses outlines.
html, body, div, span, applet, object, iframe ... {
...
outline: 0;
...
}
/* remember to define focus styles! */
:focus {
outline: 0;
}
Yes, in his explanation (and in the CSS itself) Eric does remind designers to define relevant styles for :focus… but judging by the number of sites that seem to ignore this (and often remove the related comment from the stylesheet altogether), the message doesn’t seem to have sunk in.
Anyway… hurrah! No more unsightly dotted lines on our lovely design. But what about keyboard users? Although technically they can still TAB from one element to the next, they now get no default cue as to where they are within the page (one notable exception here is Opera, where the outline is displayed regardless of stylesheets)… and if they’re Safari users, they won’t even get an indication of a link’s target in the status bar, like they would if they hovered over it with the mouse.
Only Suppress outline For Mouse Users
Is there a way to allow users navigating with the keyboard to retain the standard outline behaviour they’ve come to expect from their browser, while also ensuring that it doesn’t show display for mouse users?
Testing some convoluted style combinations
After playing with various approaches (see Better CSS outline suppression for more details), the most elegant solution also seemed to be the simplest: don’t remove the outline on :focus, do it on :active instead – after all, :active is the dynamic pseudo-class that deals explicitly with the styles that should be applied when a focusable element is clicked or otherwise activated.
a:active { outline: none; }
The only minor issues with this method: if a user activates a link and then uses the browser’s back button, the outline becomes visible. Oh, and old versions of Internet Explorer notoriously get confused by the exact meaning of :focus, :hover and :active, so this method fails in IE6 and below. Personally, I can live with both of these.
Note: at the last minute before submitting this article, I discovered a fatal flaw in my test. It appears that outline still manages to appear in the time between activating a link and the link target loading (which in hindsight is logical – after activation, the link does indeed receive focus). As my test page only used in-page links, this issue never came up before. The slightly less elegant solution is to also suppress the outline on :hover.
a:hover, a:active { outline: none; }
In Conclusion
Of course, many web designers may argue that they know what’s best, even for their keyboard-using audience. Maybe they’ve removed the default outline and are instead providing some carefully designed :focus styles. If they know for sure that these custom styles are indeed a reliable alternative for their users, more power to them… but, at the risk of sounding like Jakob “blue underlined links” Nielsen, I’d still argue that sometimes the default browser behaviours are best left alone. Complemented, yes (and if you’re already defining some fancy styles for :hover, by all means feel free to also make them display on :focus)… but not suppressed. |
2009 |
Patrick Lauke |
patricklauke |
2009-12-09T00:00:00+00:00 |
https://24ways.org/2009/dont-lose-your-focus/ |
code |
| 326 |
Don't be eval() |
JavaScript is an interpreted language, and like so many of its peers it includes the all powerful eval() function. eval() takes a string and executes it as if it were regular JavaScript code. It’s incredibly powerful and incredibly easy to abuse in ways that make your code slower and harder to maintain. As a general rule, if you’re using eval() there’s probably something wrong with your design.
Common mistakes
Here’s the classic misuse of eval(). You have a JavaScript object, foo, and you want to access a property on it – but you don’t know the name of the property until runtime. Here’s how NOT to do it:
var property = 'bar';
var value = eval('foo.' + property);
Yes it will work, but every time that piece of code runs JavaScript will have to kick back in to interpreter mode, slowing down your app. It’s also dirt ugly.
Here’s the right way of doing the above:
var property = 'bar';
var value = foo[property];
In JavaScript, square brackets act as an alternative to lookups using a dot. The only difference is that square bracket syntax expects a string.
Security issues
In any programming language you should be extremely cautious of executing code from an untrusted source. The same is true for JavaScript – you should be extremely cautious of running eval() against any code that may have been tampered with – for example, strings taken from the page query string. Executing untrusted code can leave you vulnerable to cross-site scripting attacks.
What’s it good for?
Some programmers say that eval() is B.A.D. – Broken As Designed – and should be removed from the language. However, there are some places in which it can dramatically simplify your code. A great example is for use with XMLHttpRequest, a component of the set of tools more popularly known as Ajax. XMLHttpRequest lets you make a call back to the server from JavaScript without refreshing the whole page. A simple way of using this is to have the server return JavaScript code which is then passed to eval(). Here is a simple function for doing exactly that – it takes the URL to some JavaScript code (or a server-side script that produces JavaScript) and loads and executes that code using XMLHttpRequest and eval().
function evalRequest(url) {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState==4 && xmlhttp.status==200) {
eval(xmlhttp.responseText);
}
}
xmlhttp.open("GET", url, true);
xmlhttp.send(null);
}
If you want this to work with Internet Explorer you’ll need to include this compatibility patch. |
2005 |
Simon Willison |
simonwillison |
2005-12-07T00:00:00+00:00 |
https://24ways.org/2005/dont-be-eval/ |
code |
| 264 |
Dynamic Social Sharing Images |
Way back when social media was new, you could be pretty sure that whatever you posted would be read by those who follow you. If you’d written a blog post and you wanted to share it with those who follow you, you could post a link and your followers would see it in their streams. Oh heady days!
With so many social channels and a proliferation of content and promotions flying past in everyone’s streams, it’s no longer enough to share content on social media, you have to actively sell it if you want it to be seen. You really need to make the most of every opportunity to catch a reader’s attention if you’re trying to get as many eyes as possible on that sweet, sweet social content.
One of the best ways to grab attention with your posts or tweets is to include an image. There’s heaps of research that says that having images in your posts helps them stand out to followers. Reports I found showed figures from anything from 35% to 150% improvement from just having image in a post. Unfortunately, the details were surrounded with gross words like engagement and visual marketing assets and so I had to close the page before I started to hate myself too much.
So without hard stats to quote, we’ll call it a rule of thumb. The rule of thumb is that posts with images will grab more attention than those without, so it makes sense that when adding pages to a website, you should make sure that they have social media sharing images associated with them.
Adding sharing images
The process for declaring an image to be used in places like Facebook and Twitter is very simple, and at this point is familiar to many of us. You add a meta tag to the head of the page to point to the location of the image to use. When a link to the page is added to a post, the social network will fetch the page, look for the meta tag and then use the image you specified.
<meta property="og:image" content="https://example.com/my_image.jpg">
There’s a good post on this over at CSS-Tricks if you need to bone up on the details of this and other similar meta tags for social media sharing.
This is all fine and well for content that has a very obvious choice of image to go along with it, but what if you don’t necessarily have an image? One approach is to use stock photography, but that’s not going to be right for every situation.
This was something we faced with 24 ways in 2017. We wanted to add images to the tweets we post each day announcing a new article. Some articles have images, but not all, and there tended not to be any consistency in terms of imagery from one article to the next. We always have an author photograph, but those don’t usually lend themselves directly to being the main ‘hero’ image for an article.
Putting his thinking cap on, Paul came up with a design for an image that used the author photo along with a quote extracted from the article.
One of the hand-made sharing images from 2017
Each day we would pick a quote from the article, and Paul would manually compose an image to be uploaded to the site. The results were great, but the whole process was a bit too labour intensive and relied on an individual (Paul) being available each day to do the work. I thought we could probably improve this.
Hatching a new plan
One initial idea I came up with was to script the image editor to dynamically build a new image by pulling content from our database. Sketch has plugins available to pull JSON content into a design, and our CMS can easily output JSON data, so that was one possibility.
The more I thought about this and how much I wish graphic design tools worked just a little bit more like CSS, the obvious solution hit me. We should just build it with CSS!
In fact, as the author name and image already exist in our CMS, and the visual styling is based on the design of the website, couldn’t this just be another page on the site generated by the CMS?
Breaking it down, I figured the steps needed would be something like:
Create the CSS to lay out a component that could be turned into an image
Add a new field to articles in the CMS to hold a handpicked quote
Build a new article template in the CMS to output the author name and quote dynamically for any article
… um … screenshot?
I thought I’d get cracking and see if I could figure out the final steps later.
Building the page
The first thing to tackle was the basic HTML and CSS to lay out the components for our image. That bit was really easy, as I just asked Paul to do it. Everyone should have a Paul.
Paul’s code uses a fixed dimension container in the HTML, set to 600 × 315px. This is to make it the correct aspect ratio for Facebook’s recommended image size. It’s useful to remember here that it doesn’t need to be responsive or robust, as the page only needs to lay out correctly for a screenshot and a fixed size in a known browser.
With the markup and CSS in place, I turned this into a new template. Our CMS can easily display content through any number of templates, so I created a version of the article template that was totally stripped down. It only included the author details and the quote, along with Paul’s markup.
I also added the quote as a new field on the article in the CMS, so each ‘image’ could be quickly and easily customised in the editing process.
I added a new field to the article template to capture the quote.
With very little effort, we quickly had a page to dynamically generate our ‘image’ right from the CMS. You can see any of them by adding /sharing onto the end of an article URL for any 2018 article.
Our automatically generated layout direct from the CMS
It soon became clear that the elusive Step 4 was going to be the tricky part. I can create a small page on the site that looks like an image, but how should I go about turning it into one? An obvious route is to screenshot the page by hand, but that’s going back to some of the manual steps I was trying to eliminate, and also opens up a possibility for errors to be made. But it did lead me to the thought… how could I automatically take a screenshot?
Enter Puppeteer
Puppeteer is a Node.js library that provides a nice API onto Headless Chrome. What is Headless Chrome, you ask? It’s just a version of the Chrome browser than runs from the command line without ever drawing anything to a user interface window. It loads pages, renders CSS, runs JavaScript, pretty much every normal thing that Chrome on the desktop does, but without a clicky user interface.
Headless Chrome can be used for all sorts of things such as running automated tests on front-end code after making changes, or… get this… rendering pages that can be used for screenshots. The actual process of writing some code to control Chrome and to take the screenshot is where Puppeteer comes in. Puppeteer puts a friendly layer in front of big old scary Chrome to enable us to interact with it using simple JavaScript code running in Node.
Using Puppeteer, I can write a small script that will repeatably turn a URL into an image. So simple is it to do this, that’s it’s actually Puppeteer’s ‘hello world’ example.
First you install Puppeteer. It downloads a compatible headless browser (actually Chromium) as a dependancy, so you don’t need to worry about installing that. At the command line:
npm i puppeteer
Then save a new file as example.js with this code:
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('https://example.com');
await page.screenshot({path: 'example.png'});
await browser.close();
})();
and then run it using Node:
node example.js
This will output an image file example.png to disk, which contains a screenshot of, in this case https://example.com. The logic of the code is reasonably easy to follow:
Launch a browser
Open up a new page
Goto a URL
Take a screenshot
Close the browser
The async function and await keywords are a way to have the script pause and wait for normally asynchronous code to return before proceeding. That’s useful with actions like loading a web page that might take some time to complete. They’re used with Promises, and the effect is to make asynchronous code behave as if it’s synchronous. You can read more about async and await at MDN if you’re interested.
That’s a good proof-of-concept using the basic Puppeteer example. I can take a screenshot of a URL! But what happens if I put the URL of my new special page in there?
Our content is up in the corner of the image with lots of empty space.
That’s not great. It’s okay, but not great. It looks like that, by default, Puppeteer takes a screenshot with a resolution of 800 × 600, so we need to find out how to adjust that. Fortunately, the docs aren’t the worst and I was able to find the page.setViewport() method pretty easily.
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('https://24ways.org/2018/clip-paths-know-no-bounds/sharing');
await page.setViewport({
width: 600,
height: 315
});
await page.screenshot({path: 'example.png'});
await browser.close();
})();
This worked! The screenshot is now 600 × 315 as expected. That’s exactly what we asked for. Trouble is, that’s a bit low res and it is nearly 2019 after all. While in those docs, I noticed the deviceScaleFactor option that can be passed to page.setViewport(). Setting that to 2 gives us an image of the same area of the screen, but with twice as many pixels.
await page.setViewport({
width: 600,
height: 315,
deviceScaleFactor: 2
});
Perfect! We now have a programmatic way of turning a URL into an image.
Improving the script
Rather than having a script with a fixed URL in it that outputs an image called example.png, the next step is to make that a bit more dynamic. The aim here is to have a script that we can run with a URL as an argument and have it output an image for that one page. That way we can run it manually, or hook it into part of our site’s build process to automate the generation of the image.
Our goal is to call the script like this:
node shoot-sharing-image.js https://24ways.org/2018/clip-paths-know-no-bounds/
And I want the image to come out with the name clip-paths-know-no-bounds.png. To do that, I need to have my script look for command arguments, and then to split the URL up to grab the slug from it.
// Get the URL and the slug segment from it
const url = process.argv[2];
const segments = url.split('/');
// Get the second-to-last segment (the slug)
const slug = segments[segments.length-2];
We can then use these variables later in the script, remembering to add sharing back onto the end of the URL to get our dedicated page.
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto(url + 'sharing');
await page.setViewport({
width: 600,
height: 315,
deviceScaleFactor: 2
});
await page.screenshot({path: slug + '.png'});
await browser.close();
})();
Once you’re generating the image with Node, there’s all sorts of things you can do with it. An obvious step is to move it to the correct location within your site or project.
You can also run optimisations on the file. I’m using imagemin with pngquant to reduce the file size a little.
const imagemin = require('imagemin');
const imageminPngquant = require('imagemin-pngquant');
await imagemin([slug + '.png'], 'build', {
plugins: [
imageminPngquant({quality: '75-90'})
]
});
You can see the completed example as a gist.
Integrating it with your CMS
So we now have a command we can run to take a URL and generate a custom image for that URL. It’s in a format that can be called by any sort of build script, or triggered from a publishing hook in a CMS. Exactly how you do that is going to depend on the way your site is built and the technology stack you’re using, but it’s likely not too hard as long as you can run a command as part of the process.
For 24 ways this year, I’ve been running the script by hand once each article is ready. My script adds the file to a git repo and pushes to a deployment remote that is configured to automatically deploy static assets to our server. Along with our theme of making incremental improvements, next year I’ll look to automate this one step further.
We may also look at having a few slightly different layouts to choose from, so that each day isn’t exactly the same as the last. Interestingly, we could even try some A/B tests to see if there’s any particular format of image or type of quote that does a better job of grabbing attention. There are lots of possibilities!
By using a bit of ingenuity, some custom CMS templates, and the very useful Puppeteer project, we’ve been able to reliably produce dynamic social media sharing images for all of our articles. In doing so, we reduced the dependancy on any individual for producing those images, and opened up a world of possibilities in how we use those images.
I hope you’ll give it a try! |
2018 |
Drew McLellan |
drewmclellan |
2018-12-24T00:00:00+00:00 |
https://24ways.org/2018/dynamic-social-sharing-images/ |
code |
| 314 |
Easy Ajax with Prototype |
There’s little more impressive on the web today than a appropriate touch of Ajax. Used well, Ajax brings a web interface much closer to the experience of a desktop app, and can turn a bear of an task into a pleasurable activity.
But it’s really hard, right? It involves all the nasty JavaScript that no one ever does often enough to get really good at, and the browser support is patchy, and urgh it’s just so much damn effort. Well, the good news is that – ta-da – it doesn’t have to be a headache. But man does it still look impressive. Here’s how to amaze your friends.
Introducing prototype.js
Prototype is a JavaScript framework by Sam Stephenson designed to help make developing dynamic web apps a whole lot easier. In basic terms, it’s a JavaScript file which you link into your page that then enables you to do cool stuff.
There’s loads of capability built in, a portion of which covers our beloved Ajax. The whole thing is freely distributable under an MIT-style license, so it’s good to go. What a nice man that Mr Stephenson is – friends, let us raise a hearty cup of mulled wine to his good name. Cheers! sluurrrrp.
First step is to download the latest Prototype and put it somewhere safe. I suggest underneath the Christmas tree.
Cutting to the chase
Before I go on and set up an example of how to use this, let’s just get to the crux. Here’s how Prototype enables you to make a simple Ajax call and dump the results back to the page:
var url = 'myscript.php';
var pars = 'foo=bar';
var target = 'output-div';
var myAjax = new Ajax.Updater(target, url, {method: 'get', parameters: pars});
This snippet of JavaScript does a GET to myscript.php, with the parameter foo=bar, and when a result is returned, it places it inside the element with the ID output-div on your page.
Knocking up a basic example
So to get this show on the road, there are three files we need to set up in our site alongside prototype.js. Obviously we need a basic HTML page with prototype.js linked in. This is the page the user interacts with. Secondly, we need our own JavaScript file for the glue between the interface and the stuff Prototype is doing. Lastly, we need the page (a PHP script in my case) that the Ajax is going to make its call too.
So, to that basic HTML page for the user to interact with. Here’s one I found whilst out carol singing:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>Easy Ajax</title>
<script type="text/javascript" src="prototype.js"></script>
<script type="text/javascript" src="ajax.js"></script>
</head>
<body>
<form method="get" action="greeting.php" id="greeting-form">
<div>
<label for="greeting-name">Enter your name:</label>
<input id="greeting-name" type="text" />
<input id="greeting-submit" type="submit" value="Greet me!" />
</div>
<div id="greeting"></div>
</form>
</body>
</html>
As you can see, I’ve linked in prototype.js, and also a file called ajax.js, which is where we’ll be putting our glue. (Careful where you leave your glue, kids.)
Our basic example is just going to take a name and then echo it back in the form of a seasonal greeting. There’s a form with an input field for a name, and crucially a DIV (greeting) for the result of our call. You’ll also notice that the form has a submit button – this is so that it can function as a regular form when no JavaScript is available. It’s important not to get carried away and forget the basics of accessibility.
Meanwhile, back at the server
So we need a script at the server which is going to take input from the Ajax call and return some output. This is normally where you’d hook into a database and do whatever transaction you need to before returning a result. To keep this as simple as possible, all this example here will do is take the name the user has given and add it to a greeting message. Not exactly Web 2-point-HoHoHo, but there you have it.
Here’s a quick PHP script – greeting.php – that Santa brought me early.
<?php
$the_name = htmlspecialchars($_GET['greeting-name']);
echo "<p>Season's Greetings, $the_name!</p>";
?>
You’ll perhaps want to do something a little more complex within your own projects. Just sayin’.
Gluing it all together
Inside our ajax.js file, we need to hook this all together. We’re going to take advantage of some of the handy listener routines and such that Prototype also makes available. The first task is to attach a listener to set the scene once the window has loaded. He’s how we attach an onload event to the window object and get it to call a function named init():
Event.observe(window, 'load', init, false);
Now we create our init() function to do our evil bidding. Its first job of the day is to hide the submit button for those with JavaScript enabled. After that, it attaches a listener to watch for the user typing in the name field.
function init(){
$('greeting-submit').style.display = 'none';
Event.observe('greeting-name', 'keyup', greet, false);
}
As you can see, this is going to make a call to a function called greet() onkeyup in the greeting-name field. That function looks like this:
function greet(){
var url = 'greeting.php';
var pars = 'greeting-name='+escape($F('greeting-name'));
var target = 'greeting';
var myAjax = new Ajax.Updater(target, url, {method: 'get', parameters: pars});
}
The key points to note here are that any user input needs to be escaped before putting into the parameters so that it’s URL-ready. The target is the ID of the element on the page (a DIV in our case) which will be the recipient of the output from the Ajax call.
That’s it
No, seriously. That’s everything. Try the example. Amaze your friends with your 1337 Ajax sk1llz. |
2005 |
Drew McLellan |
drewmclellan |
2005-12-01T00:00:00+00:00 |
https://24ways.org/2005/easy-ajax-with-prototype/ |
code |
| 315 |
Edit-in-Place with Ajax |
Back on day one we looked at using the Prototype library to take all the hard work out of making a simple Ajax call. While that was fun and all, it didn’t go that far towards implementing something really practical. We dipped our toes in, but haven’t learned to swim yet.
So here is swimming lesson number one. Anyone who’s used Flickr to publish their photos will be familiar with the edit-in-place system used for quickly amending titles and descriptions on photographs. Hovering over an item turns its background yellow to indicate it is editable. A simple click loads the text into an edit box, right there on the page.
Prototype includes all sorts of useful methods to help reproduce something like this for our own projects. As well as the simple Ajax GETs we learned how to do last time, we can also do POSTs (which we’ll need here) and a whole bunch of manipulations to the user interface – all through simple library calls. Here’s what we’re building, so let’s do it.
Getting Started
There are two major components to this process; the user interface manipulation and the Ajax call itself. Our set-up is much the same as last time (you may wish to read the first article if you’ve not already done so). We have a basic HTML page which links in the prototype.js file and our own editinplace.js. Here’s what Santa dropped down my chimney:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>Edit-in-Place with Ajax</title>
<link href="editinplace.css" rel="Stylesheet" type="text/css" />
<script src="prototype.js" type="text/javascript"></script>
<script src="editinplace.js" type="text/javascript"></script>
</head>
<body>
<h1>Edit-in-place</h1>
<p id="desc">Dashing through the snow on a one horse open sleigh.</p>
</body>
</html>
So that’s our page. The editable item is going to be the <p> called desc. The process goes something like this:
Highlight the area onMouseOver
Clear the highlight onMouseOut
If the user clicks, hide the area and replace with a <textarea> and buttons
Remove all of the above if the user cancels the operation
When the Save button is clicked, make an Ajax POST and show that something’s happening
When the Ajax call comes back, update the page with the new content
Events and Highlighting
The first step is to offer feedback to the user that the item is editable. This is done by shading the background colour when the user mouses over. Of course, the CSS :hover pseudo class is a straightforward way to do this, but for three reasons, I’m using JavaScript to switch class names.
:hover isn’t supported on many elements in Internet Explorer for Windows
I want to keep control over when the highlight switches off after an update, regardless of mouse position
If JavaScript isn’t available we don’t want to end up with the CSS suggesting it might be
With this in mind, here’s how editinplace.js starts:
Event.observe(window, 'load', init, false);
function init(){
makeEditable('desc');
}
function makeEditable(id){
Event.observe(id, 'click', function(){edit($(id))}, false);
Event.observe(id, 'mouseover', function(){showAsEditable($(id))}, false);
Event.observe(id, 'mouseout', function(){showAsEditable($(id), true)}, false);
}
function showAsEditable(obj, clear){
if (!clear){
Element.addClassName(obj, 'editable');
}else{
Element.removeClassName(obj, 'editable');
}
}
The first line attaches an onLoad event to the window, so that the function init() gets called once the page has loaded. In turn, init() sets up all the items on the page that we want to make editable. In this example I’ve just got one, but you can add as many as you like.
The function madeEditable() attaches the mouseover, mouseout and click events to the item we’re making editable. All showAsEditable does is add and remove the class name editable from the object. This uses the particularly cunning methods Element.addClassName() and Element.removeClassName() which enable you to cleanly add and remove effects without affecting any styling the object may otherwise have.
Oh, remember to add a rule for .editable to your style sheet:
.editable{
color: #000;
background-color: #ffffd3;
}
The Switch
As you can see above, when the user clicks on an editable item, a call is made to the function edit(). This is where we switch out the static item for a nice editable textarea. Here’s how that function looks.
function edit(obj){
Element.hide(obj);
var textarea ='<div id="' + obj.id + '_editor">
<textarea id="' + obj.id + '_edit" name="' + obj.id + '" rows="4" cols="60">'
+ obj.innerHTML + '</textarea>';
var button = '<input id="' + obj.id + '_save" type="button" value="SAVE" /> OR
<input id="' + obj.id + '_cancel" type="button" value="CANCEL" /></div>';
new Insertion.After(obj, textarea+button);
Event.observe(obj.id+'_save', 'click', function(){saveChanges(obj)}, false);
Event.observe(obj.id+'_cancel', 'click', function(){cleanUp(obj)}, false);
}
The first thing to do is to hide the object. Prototype comes to the rescue with Element.hide() (and of course, Element.show() too). Following that, we build up the textarea and buttons as a string, and then use Insertion.After() to place our new editor underneath the (now hidden) editable object.
The last thing to do before we leave the user to edit is it attach listeners to the Save and Cancel buttons to call either the saveChanges() function, or to cleanUp() after a cancel.
In the event of a cancel, we can clean up behind ourselves like so:
function cleanUp(obj, keepEditable){
Element.remove(obj.id+'_editor');
Element.show(obj);
if (!keepEditable) showAsEditable(obj, true);
}
Saving the Changes
This is where all the Ajax fun occurs. Whilst the previous article introduced Ajax.Updater() for simple Ajax calls, in this case we need a little bit more control over what happens once the response is received. For this purpose, Ajax.Request() is perfect. We can use the onSuccess and onFailure parameters to register functions to handle the response.
function saveChanges(obj){
var new_content = escape($F(obj.id+'_edit'));
obj.innerHTML = "Saving...";
cleanUp(obj, true);
var success = function(t){editComplete(t, obj);}
var failure = function(t){editFailed(t, obj);}
var url = 'edit.php';
var pars = 'id=' + obj.id + '&content=' + new_content;
var myAjax = new Ajax.Request(url, {method:'post',
postBody:pars, onSuccess:success, onFailure:failure});
}
function editComplete(t, obj){
obj.innerHTML = t.responseText;
showAsEditable(obj, true);
}
function editFailed(t, obj){
obj.innerHTML = 'Sorry, the update failed.';
cleanUp(obj);
}
As you can see, we first grab in the contents of the textarea into the variable new_content. We then remove the editor, set the content of the original object to “Saving…” to show that an update is occurring, and make the Ajax POST.
If the Ajax fails, editFailed() sets the contents of the object to “Sorry, the update failed.” Admittedly, that’s not a very helpful way to handle the error but I have to limit the scope of this article somewhere. It might be a good idea to stow away the original contents of the object (obj.preUpdate = obj.innerHTML) for later retrieval before setting the content to “Saving…”. No one likes a failure – especially a messy one.
If the Ajax call is successful, the server-side script returns the edited content, which we then place back inside the object from editComplete, and tidy up.
Meanwhile, back at the server
The missing piece of the puzzle is the server-side script for committing the changes to your database. Obviously, any solution I provide here is not going to fit your particular application. For the purposes of getting a functional demo going, here’s what I have in PHP.
<?php
$id = $_POST['id'];
$content = $_POST['content'];
echo htmlspecialchars($content);
?>
Not exactly rocket science is it? I’m just catching the content item from the POST and echoing it back. For your application to be useful, however, you’ll need to know exactly which record you should be updating. I’m passing in the ID of my <div>, which is not a fat lot of use. You can modify saveChanges() to post back whatever information your app needs to know in order to process the update.
You should also check the user’s credentials to make sure they have permission to edit whatever it is they’re editing. Basically the same rules apply as with any script in your application.
Limitations
There are a few bits and bobs that in an ideal world I would tidy up. The first is the error handling, as I’ve already mentioned. The second is that from an idealistic standpoint, I’d rather not be using innerHTML. However, the reality is that it’s presently the most efficient way of making large changes to the document. If you’re serving as XML, remember that you’ll need to replace these with proper DOM nodes.
It’s also important to note that it’s quite difficult to make something like this universally accessible. Whenever you start updating large chunks of a document based on user interaction, a lot of non-traditional devices don’t cope well. The benefit of this technique, though, is that if JavaScript is unavailable none of the functionality gets implemented at all – it fails silently. It is for this reason that this shouldn’t be used as a complete replacement for a traditional, universally accessible edit form. It’s a great time-saver for those with the ability to use it, but it’s no replacement.
See it in action
I’ve put together an example page using the inert PHP script above. That is to say, your edits aren’t committed to a database, so the example is reset when the page is reloaded. |
2005 |
Drew McLellan |
drewmclellan |
2005-12-23T00:00:00+00:00 |
https://24ways.org/2005/edit-in-place-with-ajax/ |
code |
| 238 |
Everything You Wanted To Know About Gradients (And a Few Things You Didn’t) |
Hello. I am here to discuss CSS3 gradients. Because, let’s face it, what the web really needed was more gradients.
Still, despite their widespread use (or is it overuse?), the smartly applied gradient can be a valuable contributor to a designer’s vocabulary. There’s always been a tension between the inherently two-dimensional nature of our medium, and our desire for more intensity, more depth in our designs. And a gradient can evoke so much: the splay of light across your desk, the slow decrease in volume toward the end of your favorite song, the sunset after a long day. When properly applied, graded colors bring a much needed softness to our work.
Of course, that whole ‘proper application’ thing is the tricky bit.
But given their place in our toolkit and their prominence online, it really is heartening to see we can create gradients directly with CSS. They’re part of the draft images module, and implemented in two of the major rendering engines.
Still, I’ve always found CSS gradients to be one of the more confusing aspects of CSS3. So if you’ll indulge me, let’s take a quick look at how to create CSS gradients—hopefully we can make them seem a bit more accessible, and bring a bit more art into the browser.
Gradient theory 101 (I hope that’s not really a thing)
Right. So before we dive into the code, let’s cover a few basics. Every gradient, no matter how complex, shares a few common characteristics. Here’s a straightforward one:
I spent seconds hours designing this gradient. I hope you like it.
At either end of our image, we have a final color value, or color stop: on the left, our stop is white; on the right, black. And more color-rich gradients are no different:
(Don’t ever really do this. Please. I beg you.)
It’s visually more intricate, sure. But at the heart of it, we have just seven color stops (red, orange, yellow, and so on), making for a fantastic gradient all the way.
Now, color stops alone do not a gradient make. Between each is a transition point, the fail-over point between the two stops. Now, the transition point doesn’t need to fall exactly between stops: it can be brought closer to one stop or the other, influencing the overall shape of the gradient.
A tale of two syntaxes
Armed with our new vocabulary, let’s look at a CSS gradient in the wild. Behold, the simple input button:
There’s a simple linear gradient applied vertically across the button, moving from a bright sunflowerish hue (#FAA51A, for you hex nuts in the audience) to a much richer orange (#F47A20). And here’s the CSS that makes it happen:
input[type=submit] {
background-color: #F47A20;
background-image: -moz-linear-gradient(
#FAA51A,
#F47A20
);
background-image: -webkit-gradient(linear, 0 0, 0 100%,
color-stop(0, #FAA51A),
color-stop(1, #F47A20)
);
}
I’ve borrowed David DeSandro’s most excellent formatting suggestions for gradients to make this snippet a bit more legible but, still, the code above might have turned your stomach a bit. And that’s perfectly understandable—heck, it sort of turned mine. But let’s step through the CSS slowly, and see if we can’t make it a little less terrifying.
Verbose WebKit is verbose
Here’s the syntax for our little gradient on WebKit:
background-image: -webkit-gradient(linear, 0 0, 0 100%,
color-stop(0, #FAA51A),
color-stop(1, #F47A20)
);
Woof. Quite a mouthful, no? Well, here’s what we’re looking at:
WebKit has a single -webkit-gradient property, which can be used to create either linear or radial gradients.
The next two values are the starting and ending positions for our gradient (0 0 and 0 100%, respectively). Linear gradients are simply drawn along the path between those two points, which allows us to change the direction of our gradient simply by altering its start and end points.
Afterward, we specify our color stops with the oh-so-aptly named color-stop parameter, which takes the stop’s position on the gradient (0 being the beginning, and 100% or 1 being the end) and the color itself.
For a simple two-color gradient like this, -webkit-gradient has a bit of shorthand notation to offer us:
background-image: -webkit-gradient(linear, 0 0, 0 100%,
from(#FAA51A),
to(#FAA51A)
);
from(#FAA51A) is equivalent to writing color-stop(0, #FAA51A), and to(#FAA51A) is the same as color-stop(1, #FAA51A) or color-stop(100%, #FAA51A)—in both cases, we’re simply declaring the first and last color stops in our gradient.
Terse Gecko is terse
WebKit proposed its syntax back in 2008, heavily inspired by the way gradients are drawn in the canvas specification. However, a different, leaner syntax came to the fore, eventually appearing in a draft module specification in CSS3.
Naturally, because nothing on the web was meant to be easy, this is the one that Mozilla has implemented.
Here’s how we get gradient-y in Gecko:
background-image: -moz-linear-gradient(
#FAA51A,
#F47A20
);
Wait, what? Done already? That’s right. By default, -moz-linear-gradient assumes you’re trying to create a vertical gradient, starting from the top of your element and moving to the bottom. And, if that’s the case, then you simply need to specify your color stops, delimited with a few commas.
I know: that was almost… painless. But the W3C/Mozilla syntax also affords us a fair amount of flexibility and control, by introducing features as we need them.
We can specify an origin point for our gradient:
background-image: -moz-linear-gradient(50% 100%,
#FAA51A,
#F47A20
);
As well as an angle, to give it a direction:
background-image: -moz-linear-gradient(50% 100%, 45deg,
#FAA51A,
#F47A20
);
And we can specify multiple stops, simply by adding to our comma-delimited list:
background-image: -moz-linear-gradient(50% 100%, 45deg,
#FAA51A,
#FCC,
#F47A20
);
By adding a percentage after a given color value, we can determine its position along the gradient path:
background-image: -moz-linear-gradient(50% 100%, 45deg,
#FAA51A,
#FCC 20%,
#F47A20
);
So that’s some of the flexibility implicit in the W3C/Mozilla-style syntax.
Now, I should note that both syntaxes have their respective fans. I will say that the W3C/Mozilla-style syntax makes much more sense to me, and lines up with how I think about creating gradients. But I can totally understand why some might prefer WebKit’s more verbose approach to the, well, looseness behind the -moz syntax. À chacun son gradient syntax.
Still, as the language gets refined by the W3C, I really hope some consensus is reached by the browser vendors. And with Opera signaling that it will support the W3C syntax, I suppose it falls on WebKit to do the same.
Reusing color stops for fun and profit
But CSS gradients aren’t all simple colors and shapes and whatnot: by getting inventive with individual color stops, you can create some really complex, compelling effects.
Tim Van Damme, whose brain, I believe, should be posthumously donated to science, has a particularly clever application of gradients on The Box, a site dedicated to his occasional podcast series. Now, there are a fair number of gradients applied throughout the UI, but it’s the feature image that really catches the eye.
You see, there’s nothing that says you can’t reuse color stops. And Tim’s exploited that perfectly.
He’s created a linear gradient, angled at forty-five degrees from the top left corner of the photo, starting with a fully transparent white (rgba(255, 255, 255, 0)). At the halfway mark, he’s established another color stop at an only slightly more opaque white (rgba(255, 255, 255, 0.1)), making for that incredibly gradual brightening toward the middle of the photo.
But then he has set another color stop immediately on top of it, bringing it back down to rgba(255, 255, 255, 0) again. This creates that fantastically hard edge that diagonally bisects the photo, giving the image that subtle gloss.
And his final color stop ends at the same fully transparent white, completing the effect. Hot? I do believe so.
Rocking the radials
We’ve been looking at linear gradients pretty exclusively. But I’d be remiss if I didn’t at least mention radial gradients as a viable option, including a modest one as a link accent on a navigation bar:
And here’s the relevant CSS:
background: -moz-radial-gradient(50% 100%, farthest-side,
rgb(204, 255, 255) 1%,
rgb(85, 85, 85) 15%,
rgba(85, 85, 85, 0)
);
background: -webkit-gradient(radial, 50% 100%, 0, 50% 100%, 15,
from(rgb(204, 255, 255)),
to(rgba(85, 85, 85, 0))
);
Now, the syntax builds on what we’ve already learned about linear gradients, so much of it might be familiar to you, picking out color stops and transition points, as well as the two syntaxes’ reliance on either a separate property (-moz-radial-gradient) or parameter (-webkit-gradient(radial, …)) to shift into circular mode.
Mozilla introduces another stand-alone property (-moz-radial-gradient), and accepts a starting point (50% 100%) from which the circle radiates. There’s also a size constant defined (farthest-side), which determines the reach and shape of our gradient.
WebKit is again the more verbose of the two syntaxes, requiring both starting and ending points (50% 100% in both cases). Each also accepts a radius in pixels, allowing you to control the skew and breadth of the circle.
Again, this is a fairly modest little radial gradient. Time and article length (and, let’s be honest, your author’s completely inadequate grasp of geometry) prevent me from covering radial gradients in much more detail, because they are incredibly powerful. For those interested in learning more, I can’t recommend the references at Mozilla and Apple strongly enough.
Leave no browser behind
But no matter the kind of gradients you’re working with, there is a large swathe of browsers that simply don’t support gradients. Thankfully, it’s fairly easy to declare a sensible fallback—it just depends on the kind of fallback you’d like. Essentially, gradient-blind browsers will disregard any properties containing references to either -moz-linear-gradient, -moz-radial-gradient, or -webkit-gradient, so you simply need to keep your fallback isolated from those properties.
For example: if you’d like to fall back to a flat color, simply declare a separate background-color:
.nav {
background-color: #000;
background-image: -moz-linear-gradient(rgba(0, 0, 0, 0), rgba(255, 255, 255, 0.45));
background-image: -webkit-gradient(linear, 0 0, 0 100%, from(rgba(0, 0, 0, 0)), to(rgba(255, 255, 255, 0.45)));
}
Or perhaps just create three separate background properties.
.nav {
background: #000;
background: #000 -moz-linear-gradient(rgba(0, 0, 0, 0), rgba(255, 255, 255, 0.45));
background: #000 -webkit-gradient(linear, 0 0, 0 100%, from(rgba(0, 0, 0, 0)), to(rgba(255, 255, 255, 0.45)));
}
We can even build on this to fall back to a non-gradient image:
.nav {
background: #000 <strong>url("faux-gradient-lol.png") repeat-x</strong>;
background: #000 -moz-linear-gradient(rgba(0, 0, 0, 0), rgba(255, 255, 255, 0.45));
background: #000 -webkit-gradient(linear, 0 0, 0 100%, from(rgba(0, 0, 0, 0)), to(rgba(255, 255, 255, 0.45)));
}
No matter the approach you feel most appropriate to your design, it’s really just a matter of keeping your fallback design quarantined from its CSS3-ified siblings.
(If you’re feeling especially masochistic, there’s even a way to get simple linear gradients working in IE via Microsoft’s proprietary filters. Of course, those come with considerable performance penalties that even Microsoft is quick to point out, so I’d recommend avoiding those.
And don’t tell Andy Clarke I told you, or he’ll probably unload his Derringer at me. Or something.)
Go forth and, um, gradientify!
It’s entirely possible your head’s spinning. Heck, mine is, but that might be the effects of the ’nog. But maybe you’re wondering why you should care about CSS gradients. After all, images are here right now, and work just fine.
Well, there are some quick benefits that spring to mind: fewer HTTP requests are needed; CSS3 gradients are easily made scalable, making them ideal for variable widths and heights; and finally, they’re easily modifiable by tweaking a few CSS properties. Because, let’s face it, less time spent yelling at Photoshop is a very, very good thing.
Of course, CSS-generated gradients are not without their drawbacks. The syntax can be confusing, and it’s still under development at the W3C. As we’ve seen, browser support is still very much in flux. And it’s possible that gradients themselves have some real performance drawbacks—so test thoroughly, and gradient carefully.
But still, as syntaxes converge, and support improves, I think generated gradients can make a compelling tool in our collective belts. The tasteful design is, of course, entirely up to you.
So have fun, and get gradientin’. |
2010 |
Ethan Marcotte |
ethanmarcotte |
2010-12-22T00:00:00+00:00 |
https://24ways.org/2010/everything-you-wanted-to-know-about-gradients/ |
code |
| 310 |
Fairytale of new Promise |
There are only four good Christmas songs.
I know, yeah, JavaScript or whatever. We’ll get to that in a minute, I promise.
First—and I cannot stress this enough— there are four good Christmas songs. You’re free to disagree with me here, of course, but please try to understand that you will be wrong.
They don’t all have the most safe-for-work titles; I can’t list all of them here, but if you choose to let your fingers do the walkin’ to your nearest search engine, I will say that one was released by the band FEAR way back in 1982 and one was on Run the Jewels’ self-titled debut album. The lyrics are a hell of a lot worse than the titles, so maybe wait until you get home from work before you queue them up. Wear headphones, if you’ve got thin walls.
For my money, though, the two I can reference by name are the top of that small heap: Tom Waits’ Christmas Card from a Hooker in Minneapolis, and The Pogues’ Fairytale of New York. The former once held the honor of being the only good Christmas song—about which which I was also unequivocally correct, right up until I changed my mind. It’s not the song up for discussion today, but feel free to familiarize yourself just the same—I’ll wait.
Fairytale of New York—the top of the list—starts out by hinting at some pretty standard holiday fare; dreams and cheer and whatnot. Typical seasonal stuff, so long as you ignore that the story seems to be recounted as a drunken flashback in a jail cell. You can probably make a few guesses at the underlying spirit of the song based on that framing: following a lucky break, our bright-eyed protagonists move to New York in search of fame and fortune, only to quickly descend into bad decisions, name-calling, and vaguely festive chaos.
This song speaks to me on a couple of levels, not the least of which is as a retelling of my day-to-day interactions with JavaScript. Each day’s melody might vary a little bit, granted, but the lyrics almost always follow a pretty clear arc toward “PARENTAL ADVISORY: EXPLICIT CONTENT.” You might have heard a similar tune yourself; it goes a little somethin’ like setTimeout(function() { console.log( "this should be happening last" ); }, 1000); . Callbacks are calling callbacks calling callbacks and something is happening somewhere, as the JavaScript interpreter plods through our code start-to-finish, line-by-line, step-by-step. If we need to take actions based on the results of something that could take its sweet time resolving, well, we’d better fiddle with the order of things to make sure those actions don’t happen too soon.
“But I can see a better time,” as the song says, “when all our dreams come true.” So, with that Pogues brand of holiday spirit squarely in mind—by which I mean that your humble narrator is almost certainly drunk, and may be incarcerated at the time of publication—gather ’round for a story of hope, of hardships, of semi-asynchronous JavaScript programming, and ultimately: of Promise unfulfilled.
The Main Thread
JavaScript is single-minded, in a manner of speaking. Anything we tell the JavaScript runtime to do goes into a single-file queue; you’ll see it referred to as the “main thread,” or “UI thread.” That thread can be shared by a number of critical browser processes, like rendering and re-rendering parts of the page, and user interactions ranging from the simple—say, highlighting text—to the more complex—interacting with form elements.
If that sounds a little scary to you, well, that’s because it is. The more complex our scripts, the more we’re cramming into that single-file main thread, to be processed along with—say—some of our CSS animations. Too much JavaScript clogging up the main thread means a lot of user-facing performance jankiness. Getting away from that single thread is a big part of all the excitement around Web Workers, which allow us to offload entire scripts into their own dedicated background threads—though not without limitations of their own. Outside of Web Workers, that everything-thread is the only game in town: scripts executed one thing at a time, functions calling functions calling functions, taking numbers and crowding up the same deli counter as a user’s interactions—which, in this already strained metaphor, would be ham, I guess?
Asynchronous JavaScript
Now, those queued actions may include asynchronous things. For example: AJAX callbacks, setTimeout/setInterval, and addEventListener won’t block the main thread while we’re waiting for a request to come back, a timer to tick away, or an event to trigger. Once those things do kick in, though, the actions they’re meant to perform will get shuffled right back into that single-thread queue.
There are a couple of places you might have written asynchronously-fired JavaScript, even if you’re not super familiar with the overarching concept: XMLHttpRequest—“AJAX,” if ya nasty—or just kicking off a function once a user triggers a click or mouseenter event. Event-driven development is writ a little larger, with the overall flow of the script dictated by events, both internal and external. Writing event-driven JavaScript applications is a step in the right direction for sure—it won’t cure what ails the main thread, but it does work with the medium in a reasonable way. Event-driven development allows us to manage our use of the main thread in a way that makes sense. If any of this rings a bell for you, the motivation for Promises should feel familiar.
For example, a custom init event might kick things off, and fire a create event that applies our classes and restructures our markup which, on completion, fires a bindEvents event to handle all the event listeners for user interaction. There might not sound like much difference between that and one big function that kicks off, manipulates the DOM, and binds our events line-by-line—but in a script of sufficient size and complexity we’re not only provided with a decoupled flow through the script, but obvious touchpoints for future updates and a predictable structure for ongoing maintenance.
This pattern falls apart a little where we were still creating, binding, and listening for events in the same top-to-bottom, one-item-at-a-time way—we had to set a listener on a given object before the event fires, or nothing would happen:
// Create the event:
var event = document.createEvent( "Event" );
// Name the event:
event.initEvent( "doTheStuff", true, true );
// Listen for the custom `doTheStuff` event on `window`:
window.addEventListener( "doTheStuff", initializeEverything );
// Fire the custom event
window.dispatchEvent( event );
This example is a little contrived, and this stuff is a lot more manageable for sure with the addition of a framework, but that’s the basic gist: create and name the event, add a listener for the event, and—after setting our listener—dispatch the event.
Events and callbacks aren’t the only game in town for weaving our way in and out of the main thread, though—at least, not anymore.
Promises
A Promise is, at the risk of sounding sentimental, pure potential—an empty container into which a value eventually results. A Promise can exist in several states: “pending,” while the computation they contain is being performed or “resolved” once that computation is complete. Once resolved, a Promise is “fulfilled” if it gave us back something we expect, or “rejected” if it didn’t.
The Promise constructor accepts a callback with two arguments: resolve and reject. We perform an action—asynchronous or otherwise—within that callback. If everything in there has gone according to plan, we call resolve. If something has gone awry, we call reject—with an error, conventionally. To illustrate, let’s tack something together with a pretty decent chance of doing what we don’t want: a promise meant only to give us the number 1, but has a chance of giving us back a 2. No reasonable person would ever do this, of course, but I wouldn’t necessarily put it past me.
var promisedOne = new Promise( function( resolve, reject ) {
var coinToss = Math.floor( Math.random() * 2 ) + 1;
if( coinToss === 1 ) {
resolve( coinToss );
} else {
reject( new Error( "That ain’t a one." ) );
}
});
There’s nothing too surprising in there, after you boil it all down. It’s a little return-y, with the exception that we’re flagging results as “as expected” or “something went wrong.”
Tapping into that Promise uses another new keyword: then—and as someone who attempts to make sense of JavaScript by breaking it down to plain ol’ human-language, I’m a big fan of this syntax. then is tacked onto our Promise identifier, and does just what it says on the tin: once the Promise is resolved, then do one of two things, both supplied as callbacks: the first in the case of a fulfilled promise, and the second in the case of a rejected one. Those two callbacks will have, as arguments, the results we specified with resolve orreject, respectively. It sounds like a lot in prose, but in code it’s a pretty simple pattern:
promisedOne.then( function( result ) {
console.log( result );
}, function( error ) {
console.error( error );
});
If you’ve spent any time working with AJAX—jQuery-wise, in particular—you’ve seen something like this pattern before: a success callback and an error callback. The state of a promise, once fulfilled or rejected, cannot be changed—any reference we make to promisedOne will have a single, fixed result.
It may not look like too much the way I’m using it here, but it’s powerful stuff—a pattern for asynchronously resolving anything. I’ve recently used Promises alongside a script that emulates Font Load Events, to apply webfonts asynchronously and avoid a potential performance hit. Font Face Observer allows us to, as the name implies, determine when the files referenced by our @font-face rules have finished loading.
var fontObserver = new FontFaceObserver( "Fancy Font" );
fontObserver.check().then(function() {
document.documentElement.className += " fonts-loaded";
}, function( error ) {
console.error( error );
});
fontObserver.check() gives us back a Promise, allowing us to chain on a then containing our callbacks for success and failure. We use the fulfilled callback to bolt a class onto the page once the font file has been fully transferred. We don’t bother including an argument in the first function, since we don’t care about the result itself so much as we care that the promise resolved without error—we’re not doing anything with the resolved value, just adding a class to the page. We do include the error argument, since we’ll want to know what happened should something go wrong.
Now, this isn’t the tidiest syntax around—at least to my eyes—with those two functions just kinda floating in a then. Luckily there’s an similar alternative syntax; one that I find a bit easier to parse at-a-glance:
fontObserver.check()
.then(function() {
document.documentElement.className += " fonts-loaded";
})
.catch(function( error ) {
console.log( error );
});
The first callback inside then provides us with our success state, while the catch provides us with a single, explicit “something went wrong” callback. The two syntaxes aren’t completely identical in all situations, but for a simple case like this, I find it a little neater.
The Common Thread
I guess I still owe you an explanation, huh. Not about the JavaScript-whatever; I think I’ve explained that plenty. No, I mean Fairytale of New York, and why it’s perched up there at the top of the four (4) song heap.
Fairytale is a sad song, ostensibly. If you follow the main thread—start to finish, line-by-line, step by step— Fairytale is a sad song. And I can see you out there, visions of Die Hard dancing in your heads: “but is it a Christmas song?”
Well, for my money, nothing says “holidays” quite like unreliable narration.
Shane MacGowan, the song’s author, has placed the first verse about “Christmas Eve in the drunk tank” as happening right after the “lucky one, came in eighteen-to-one”—not at the chronological end of the story. That means the song might not be mostly drunken flashback, but all of it a single, overarching flashback including a Christmas Eve in protective custody. It could be that the man and woman are, together, recounting times long past—good times and bad times—maybe not even in chronological order. Hell, the “NYPD Choir” mentioned in the chorus? There’s no such thing.
We’re not big Christmas folks, my family and I. But just the same, every year, the handful of us get together, and every year—like clockwork—there’s a lull in conversation, there’s a sharp exhale, and Ma says “we all made it.” Not to a house, not to a dinner, but through another year, to another Christmas. At this point, without fail, someone starts telling a story—and one begets another, and so on. Sometimes the stories are happy, sometimes they’re sad, more often than not they’re both. Some are about things we were lucky to walk away from, some are about a time when another one of us didn’t.
Start-to-finish, line-by-line, step-by-step, the main thread through the year doesn’t change, and maybe there isn’t a whole lot we can do to change it. But by carefully weaving our way in and out of that thread—stories all out of sync and resolving one way or the other, with the results determined by questionably reliable narrators—we can change the way we interact with it and, little by little, we can start making sense of it. |
2016 |
Mat Marquis |
matmarquis |
2016-12-19T00:00:00+00:00 |
https://24ways.org/2016/fairytale-of-new-promise/ |
code |
| 249 |
Fast Autocomplete Search for Your Website |
Every website deserves a great search engine - but building a search engine can be a lot of work, and hosting it can quickly get expensive.
I’m going to build a search engine for 24 ways that’s fast enough to support autocomplete (a.k.a. typeahead) search queries and can be hosted for free. I’ll be using wget, Python, SQLite, Jupyter, sqlite-utils and my open source Datasette tool to build the API backend, and a few dozen lines of modern vanilla JavaScript to build the interface.
Try it out here, then read on to see how I built it.
First step: crawling the data
The first step in building a search engine is to grab a copy of the data that you plan to make searchable.
There are plenty of potential ways to do this: you might be able to pull it directly from a database, or extract it using an API. If you don’t have access to the raw data, you can imitate Google and write a crawler to extract the data that you need.
I’m going to do exactly that against 24 ways: I’ll build a simple crawler using wget, a command-line tool that features a powerful “recursive” mode that’s ideal for scraping websites.
We’ll start at the https://24ways.org/archives/ page, which links to an archived index for every year that 24 ways has been running.
Then we’ll tell wget to recursively crawl the website, using the --recursive flag.
We don’t want to fetch every single page on the site - we’re only interested in the actual articles. Luckily, 24 ways has nicely designed URLs, so we can tell wget that we only care about pages that start with one of the years it has been running, using the -I argument like this: -I /2005,/2006,/2007,/2008,/2009,/2010,/2011,/2012,/2013,/2014,/2015,/2016,/2017
We want to be polite, so let’s wait for 2 seconds between each request rather than hammering the site as fast as we can: --wait 2
The first time I ran this, I accidentally downloaded the comments pages as well. We don’t want those, so let’s exclude them from the crawl using -X "/*/*/comments".
Finally, it’s useful to be able to run the command multiple times without downloading pages that we have already fetched. We can use the --no-clobber option for this.
Tie all of those options together and we get this command:
wget --recursive --wait 2 --no-clobber
-I /2005,/2006,/2007,/2008,/2009,/2010,/2011,/2012,/2013,/2014,/2015,/2016,/2017
-X "/*/*/comments"
https://24ways.org/archives/
If you leave this running for a few minutes, you’ll end up with a folder structure something like this:
$ find 24ways.org
24ways.org
24ways.org/2013
24ways.org/2013/why-bother-with-accessibility
24ways.org/2013/why-bother-with-accessibility/index.html
24ways.org/2013/levelling-up
24ways.org/2013/levelling-up/index.html
24ways.org/2013/project-hubs
24ways.org/2013/project-hubs/index.html
24ways.org/2013/credits-and-recognition
24ways.org/2013/credits-and-recognition/index.html
...
As a quick sanity check, let’s count the number of HTML pages we have retrieved:
$ find 24ways.org | grep index.html | wc -l
328
There’s one last step! We got everything up to 2017, but we need to fetch the articles for 2018 (so far) as well. They aren’t linked in the /archives/ yet so we need to point our crawler at the site’s front page instead:
wget --recursive --wait 2 --no-clobber
-I /2018
-X "/*/*/comments"
https://24ways.org/
Thanks to --no-clobber, this is safe to run every day in December to pick up any new content.
We now have a folder on our computer containing an HTML file for every article that has ever been published on the site! Let’s use them to build ourselves a search index.
Building a search index using SQLite
There are many tools out there that can be used to build a search engine. You can use an open-source search server like Elasticsearch or Solr, a hosted option like Algolia or Amazon CloudSearch or you can tap into the built-in search features of relational databases like MySQL or PostgreSQL.
I’m going to use something that’s less commonly used for web applications but makes for a powerful and extremely inexpensive alternative: SQLite.
SQLite is the world’s most widely deployed database, even though many people have never even heard of it. That’s because it’s designed to be used as an embedded database: it’s commonly used by native mobile applications and even runs as part of the default set of apps on the Apple Watch!
SQLite has one major limitation: unlike databases like MySQL and PostgreSQL, it isn’t really designed to handle large numbers of concurrent writes. For this reason, most people avoid it for building web applications.
This doesn’t matter nearly so much if you are building a search engine for infrequently updated content - say one for a site that only publishes new content on 24 days every year.
It turns out SQLite has very powerful full-text search functionality built into the core database - the FTS5 extension.
I’ve been doing a lot of work with SQLite recently, and as part of that, I’ve been building a Python utility library to make building new SQLite databases as easy as possible, called sqlite-utils. It’s designed to be used within a Jupyter notebook - an enormously productive way of interacting with Python code that’s similar to the Observable notebooks Natalie described on 24 ways yesterday.
If you haven’t used Jupyter before, here’s the fastest way to get up and running with it - assuming you have Python 3 installed on your machine. We can use a Python virtual environment to ensure the software we are installing doesn’t clash with any other installed packages:
$ python3 -m venv ./jupyter-venv
$ ./jupyter-venv/bin/pip install jupyter
# ... lots of installer output
# Now lets install some extra packages we will need later
$ ./jupyter-venv/bin/pip install beautifulsoup4 sqlite-utils html5lib
# And start the notebook web application
$ ./jupyter-venv/bin/jupyter-notebook
# This will open your browser to Jupyter at http://localhost:8888/
You should now be in the Jupyter web application. Click New -> Python 3 to start a new notebook.
A neat thing about Jupyter notebooks is that if you publish them to GitHub (either in a regular repository or as a Gist), it will render them as HTML. This makes them a very powerful way to share annotated code. I’ve published the notebook I used to build the search index on my GitHub account.
Here’s the Python code I used to scrape the relevant data from the downloaded HTML files. Check out the notebook for a line-by-line explanation of what’s going on.
from pathlib import Path
from bs4 import BeautifulSoup as Soup
base = Path("/Users/simonw/Dropbox/Development/24ways-search")
articles = list(base.glob("*/*/*/*.html"))
# articles is now a list of paths that look like this:
# PosixPath('...24ways-search/24ways.org/2013/why-bother-with-accessibility/index.html')
docs = []
for path in articles:
year = str(path.relative_to(base)).split("/")[1]
url = 'https://' + str(path.relative_to(base).parent) + '/'
soup = Soup(path.open().read(), "html5lib")
author = soup.select_one(".c-continue")["title"].split(
"More information about"
)[1].strip()
author_slug = soup.select_one(".c-continue")["href"].split(
"/authors/"
)[1].split("/")[0]
published = soup.select_one(".c-meta time")["datetime"]
contents = soup.select_one(".e-content").text.strip()
title = soup.find("title").text.split(" ◆")[0]
try:
topic = soup.select_one(
'.c-meta a[href^="/topics/"]'
)["href"].split("/topics/")[1].split("/")[0]
except TypeError:
topic = None
docs.append({
"title": title,
"contents": contents,
"year": year,
"author": author,
"author_slug": author_slug,
"published": published,
"url": url,
"topic": topic,
})
After running this code, I have a list of Python dictionaries representing each of the documents that I want to add to the index. The list looks something like this:
[
{
"title": "Why Bother with Accessibility?",
"contents": "Web accessibility (known in other fields as inclus...",
"year": "2013",
"author": "Laura Kalbag",
"author_slug": "laurakalbag",
"published": "2013-12-10T00:00:00+00:00",
"url": "https://24ways.org/2013/why-bother-with-accessibility/",
"topic": "design"
},
{
"title": "Levelling Up",
"contents": "Hello, 24 ways. Iu2019m Ashley and I sell property ins...",
"year": "2013",
"author": "Ashley Baxter",
"author_slug": "ashleybaxter",
"published": "2013-12-06T00:00:00+00:00",
"url": "https://24ways.org/2013/levelling-up/",
"topic": "business"
},
...
My sqlite-utils library has the ability to take a list of objects like this and automatically create a SQLite database table with the right schema to store the data. Here’s how to do that using this list of dictionaries.
import sqlite_utils
db = sqlite_utils.Database("/tmp/24ways.db")
db["articles"].insert_all(docs)
That’s all there is to it! The library will create a new database and add a table to it called articles with the necessary columns, then insert all of the documents into that table.
(I put the database in /tmp/ for the moment - you can move it to a more sensible location later on.)
You can inspect the table using the sqlite3 command-line utility (which comes with OS X) like this:
$ sqlite3 /tmp/24ways.db
sqlite> .headers on
sqlite> .mode column
sqlite> select title, author, year from articles;
title author year
------------------------------ ------------ ----------
Why Bother with Accessibility? Laura Kalbag 2013
Levelling Up Ashley Baxte 2013
Project Hubs: A Home Base for Brad Frost 2013
Credits and Recognition Geri Coady 2013
Managing a Mind Christopher 2013
Run Ragged Mark Boulton 2013
Get Started With GitHub Pages Anna Debenha 2013
Coding Towards Accessibility Charlie Perr 2013
...
<Ctrl+D to quit>
There’s one last step to take in our notebook. We know we want to use SQLite’s full-text search feature, and sqlite-utils has a simple convenience method for enabling it for a specified set of columns in a table. We want to be able to search by the title, author and contents fields, so we call the enable_fts() method like this:
db["articles"].enable_fts(["title", "author", "contents"])
Introducing Datasette
Datasette is the open-source tool I’ve been building that makes it easy to both explore SQLite databases and publish them to the internet.
We’ve been exploring our new SQLite database using the sqlite3 command-line tool. Wouldn’t it be nice if we could use a more human-friendly interface for that?
If you don’t want to install Datasette right now, you can visit https://search-24ways.herokuapp.com/ to try it out against the 24 ways search index data. I’ll show you how to deploy Datasette to Heroku like this later in the article.
If you want to install Datasette locally, you can reuse the virtual environment we created to play with Jupyter:
./jupyter-venv/bin/pip install datasette
This will install Datasette in the ./jupyter-venv/bin/ folder. You can also install it system-wide using regular pip install datasette.
Now you can run Datasette against the 24ways.db file we created earlier like so:
./jupyter-venv/bin/datasette /tmp/24ways.db
This will start a local webserver running. Visit http://localhost:8001/ to start interacting with the Datasette web application.
If you want to try out Datasette without creating your own 24ways.db file you can download the one I created directly from https://search-24ways.herokuapp.com/24ways-ae60295.db
Publishing the database to the internet
One of the goals of the Datasette project is to make deploying data-backed APIs to the internet as easy as possible. Datasette has a built-in command for this, datasette publish. If you have an account with Heroku or Zeit Now, you can deploy a database to the internet with a single command. Here’s how I deployed https://search-24ways.herokuapp.com/ (running on Heroku’s free tier) using datasette publish:
$ ./jupyter-venv/bin/datasette publish heroku /tmp/24ways.db --name search-24ways
-----> Python app detected
-----> Installing requirements with pip
-----> Running post-compile hook
-----> Discovering process types
Procfile declares types -> web
-----> Compressing...
Done: 47.1M
-----> Launching...
Released v8
https://search-24ways.herokuapp.com/ deployed to Heroku
If you try this out, you’ll need to pick a different --name, since I’ve already taken search-24ways.
You can run this command as many times as you like to deploy updated versions of the underlying database.
Searching and faceting
Datasette can detect tables with SQLite full-text search configured, and will add a search box directly to the page. Take a look at http://search-24ways.herokuapp.com/24ways-b607e21/articles to see this in action.
SQLite search supports wildcards, so if you want autocomplete-style search where you don’t need to enter full words to start getting results you can add a * to the end of your search term. Here’s a search for access* which returns articles on accessibility:
http://search-24ways.herokuapp.com/24ways-ae60295/articles?_search=acces%2A
A neat feature of Datasette is the ability to calculate facets against your data. Here’s a page showing search results for svg with facet counts calculated against both the year and the topic columns:
http://search-24ways.herokuapp.com/24ways-ae60295/articles?_search=svg&_facet=year&_facet=topic
Every page visible via Datasette has a corresponding JSON API, which can be accessed using the JSON link on the page - or by adding a .json extension to the URL:
http://search-24ways.herokuapp.com/24ways-ae60295/articles.json?_search=acces%2A
Better search using custom SQL
The search results we get back from ../articles?_search=svg are OK, but the order they are returned in is not ideal - they’re actually being returned in the order they were inserted into the database! You can see why this is happening by clicking the View and edit SQL link on that search results page.
This exposes the underlying SQL query, which looks like this:
select rowid, * from articles where rowid in (
select rowid from articles_fts where articles_fts match :search
) order by rowid limit 101
We can do better than this by constructing a custom SQL query. Here’s the query we will use instead:
select
snippet(articles_fts, -1, 'b4de2a49c8', '8c94a2ed4b', '...', 100) as snippet,
articles_fts.rank, articles.title, articles.url, articles.author, articles.year
from articles
join articles_fts on articles.rowid = articles_fts.rowid
where articles_fts match :search || "*"
order by rank limit 10;
You can try this query out directly - since Datasette opens the underling SQLite database in read-only mode and enforces a one second time limit on queries, it’s safe to allow users to provide arbitrary SQL select queries for Datasette to execute.
There’s a lot going on here! Let’s break the SQL down line-by-line:
select
snippet(articles_fts, -1, 'b4de2a49c8', '8c94a2ed4b', '...', 100) as snippet,
We’re using snippet(), a built-in SQLite function, to generate a snippet highlighting the words that matched the query. We use two unique strings that I made up to mark the beginning and end of each match - you’ll see why in the JavaScript later on.
articles_fts.rank, articles.title, articles.url, articles.author, articles.year
These are the other fields we need back - most of them are from the articles table but we retrieve the rank (representing the strength of the search match) from the magical articles_fts table.
from articles
join articles_fts on articles.rowid = articles_fts.rowid
articles is the table containing our data. articles_fts is a magic SQLite virtual table which implements full-text search - we need to join against it to be able to query it.
where articles_fts match :search || "*"
order by rank limit 10;
:search || "*" takes the ?search= argument from the page querystring and adds a * to the end of it, giving us the wildcard search that we want for autocomplete. We then match that against the articles_fts table using the match operator. Finally, we order by rank so that the best matching results are returned at the top - and limit to the first 10 results.
How do we turn this into an API? As before, the secret is to add the .json extension. Datasette actually supports multiple shapes of JSON - we’re going to use ?_shape=array to get back a plain array of objects:
JSON API call to search for articles matching SVG
The HTML version of that page shows the time taken to execute the SQL in the footer. Hitting refresh a few times, I get response times between 2 and 5ms - easily fast enough to power a responsive autocomplete feature.
A simple JavaScript autocomplete search interface
I considered building this using React or Svelte or another of the myriad of JavaScript framework options available today, but then I remembered that vanilla JavaScript in 2018 is a very productive environment all on its own.
We need a few small utility functions: first, a classic debounce function adapted from this one by David Walsh:
function debounce(func, wait, immediate) {
let timeout;
return function() {
let context = this, args = arguments;
let later = () => {
timeout = null;
if (!immediate) func.apply(context, args);
};
let callNow = immediate && !timeout;
clearTimeout(timeout);
timeout = setTimeout(later, wait);
if (callNow) func.apply(context, args);
};
};
We’ll use this to only send fetch() requests a maximum of once every 100ms while the user is typing.
Since we’re rendering data that might include HTML tags (24 ways is a site about web development after all), we need an HTML escaping function. I’m amazed that browsers still don’t bundle a default one of these:
const htmlEscape = (s) => s.replace(
/>/g, '>'
).replace(
/</g, '<'
).replace(
/&/g, '&'
).replace(
/"/g, '"'
).replace(
/'/g, '''
);
We need some HTML for the search form, and a div in which to render the results:
<h1>Autocomplete search</h1>
<form>
<p><input id="searchbox" type="search" placeholder="Search 24ways" style="width: 60%"></p>
</form>
<div id="results"></div>
And now the autocomplete implementation itself, as a glorious, messy stream-of-consciousness of JavaScript:
// Embed the SQL query in a multi-line backtick string:
const sql = `select
snippet(articles_fts, -1, 'b4de2a49c8', '8c94a2ed4b', '...', 100) as snippet,
articles_fts.rank, articles.title, articles.url, articles.author, articles.year
from articles
join articles_fts on articles.rowid = articles_fts.rowid
where articles_fts match :search || "*"
order by rank limit 10`;
// Grab a reference to the <input type="search">
const searchbox = document.getElementById("searchbox");
// Used to avoid race-conditions:
let requestInFlight = null;
searchbox.onkeyup = debounce(() => {
const q = searchbox.value;
// Construct the API URL, using encodeURIComponent() for the parameters
const url = (
"https://search-24ways.herokuapp.com/24ways-866073b.json?sql=" +
encodeURIComponent(sql) +
`&search=${encodeURIComponent(q)}&_shape=array`
);
// Unique object used just for race-condition comparison
let currentRequest = {};
requestInFlight = currentRequest;
fetch(url).then(r => r.json()).then(d => {
if (requestInFlight !== currentRequest) {
// Avoid race conditions where a slow request returns
// after a faster one.
return;
}
let results = d.map(r => `
<div class="result">
<h3><a href="${r.url}">${htmlEscape(r.title)}</a></h3>
<p><small>${htmlEscape(r.author)} - ${r.year}</small></p>
<p>${highlight(r.snippet)}</p>
</div>
`).join("");
document.getElementById("results").innerHTML = results;
});
}, 100); // debounce every 100ms
There’s just one more utility function, used to help construct the HTML results:
const highlight = (s) => htmlEscape(s).replace(
/b4de2a49c8/g, '<b>'
).replace(
/8c94a2ed4b/g, '</b>'
);
This is what those unique strings passed to the snippet() function were for.
Avoiding race conditions in autocomplete
One trick in this code that you may not have seen before is the way race-conditions are handled. Any time you build an autocomplete feature, you have to consider the following case:
User types acces
Browser sends request A - querying documents matching acces*
User continues to type accessibility
Browser sends request B - querying documents matching accessibility*
Request B returns. It was fast, because there are fewer documents matching the full term
The results interface updates with the documents from request B, matching accessibility*
Request A returns results (this was the slower of the two requests)
The results interface updates with the documents from request A - results matching access*
This is a terrible user experience: the user saw their desired results for a brief second, and then had them snatched away and replaced with those results from earlier on.
Thankfully there’s an easy way to avoid this. I set up a variable in the outer scope called requestInFlight, initially set to null.
Any time I start a new fetch() request, I create a new currentRequest = {} object and assign it to the outer requestInFlight as well.
When the fetch() completes, I use requestInFlight !== currentRequest to sanity check that the currentRequest object is strictly identical to the one that was in flight. If a new request has been triggered since we started the current request we can detect that and avoid updating the results.
It’s not a lot of code, really
And that’s the whole thing! The code is pretty ugly, but when the entire implementation clocks in at fewer than 70 lines of JavaScript, I honestly don’t think it matters. You’re welcome to refactor it as much you like.
How good is this search implementation? I’ve been building search engines for a long time using a wide variety of technologies and I’m happy to report that using SQLite in this way is genuinely a really solid option. It scales happily up to hundreds of MBs (or even GBs) of data, and the fact that it’s based on SQL makes it easy and flexible to work with.
A surprisingly large number of desktop and mobile applications you use every day implement their search feature on top of SQLite.
More importantly though, I hope that this demonstrates that using Datasette for an API means you can build relatively sophisticated API-backed applications with very little backend programming effort. If you’re working with a small-to-medium amount of data that changes infrequently, you may not need a more expensive database. Datasette-powered applications easily fit within the free tier of both Heroku and Zeit Now.
For more of my writing on Datasette, check out the datasette tag on my blog. And if you do build something fun with it, please let me know on Twitter. |
2018 |
Simon Willison |
simonwillison |
2018-12-19T00:00:00+00:00 |
https://24ways.org/2018/fast-autocomplete-search-for-your-website/ |
code |
| 209 |
Feeding the Audio Graph |
In 2004, I was given an iPod.
I count this as one of the most intuitive pieces of technology I’ve ever owned. It wasn’t because of the the snazzy (colour!) menus or circular touchpad. I loved how smoothly it fitted into my life. I could plug in my headphones and listen to music while I was walking around town. Then when I got home, I could plug it into an amplifier and carry on listening there.
There was no faff. It didn’t matter if I could find my favourite mix tape, or if my WiFi was flakey - it was all just there.
Nowadays, when I’m trying to pair my phone with some Bluetooth speakers, or can’t find my USB-to-headphone jack, or even access any music because I don’t have cellular reception; I really miss this simplicity.
The Web Audio API
I think the Web Audio API feels kind of like my iPod did.
It’s different from most browser APIs - rather than throwing around data, or updating DOM elements - you plug together a graph of audio nodes, which the browser uses to generate, process, and play sounds.
The thing I like about it is that you can totally plug it into whatever you want, and it’ll mostly just work.
So, let’s get started. First of all we want an audio source.
<audio src="night-owl.mp3" controls />
(Song - Night Owl by Broke For Free)
This totally works. However, it’s not using the Web Audio API, so we can’t access or modify the sound it makes.
To hook this up to our audio graph, we can use an AudioSourceNode. This captures the sound from the element, and lets us connect to other nodes in a graph.
const audioCtx = new AudioContext()
const audio = document.querySelector('audio')
const input = audioCtx.createAudioSourceNode(audio)
input.connect(audioCtx.destination)
Great. We’ve made something that looks and sounds exactly the same as it did before. Go us.
Gain
Let’s plug in a GainNode - this allows you to alter the amplitude (volume) of an an audio stream.
We can hook this node up to an <input> element by setting the gain property of the node. (The syntax for this is kind of weird because it’s an AudioParam which has options to set values at precise intervals).
const node = audioCtx.createGain()
const input = document.querySelector('input')
input.oninput = () => node.gain.value = parseFloat(input.value)
input.connect(node)
node.connect(audioCtx.destination)
You can now see a range input, which can be dragged to update the state of our graph. This input could be any kind of element, so now you’ll be free to build the volume control of your dreams.
There’s a number of nodes that let you modify/filter an audio stream in more interesting ways. Head over to the MDN Web Audio page for a list of them.
Analysers
Something else we can add to our graph is an AnalyserNode. This doesn’t modify the audio at all, but allows us to inspect the sounds that are flowing through it. We can put this into our graph between our AudioSourceNode and the GainNode.
const analyser = audioCtx.createAnalyser()
input.connect(analyser)
analyser.connect(gain)
gain.connect(audioCtx.destination)
And now we have an analyser. We can access it from elsewhere to drive any kind of visuals. For instance, if we wanted to draw lines on a canvas we could totally do that:
const waveform = new Uint8Array(analyser.fftSize)
const frequencies = new Uint8Array(analyser.frequencyBinCount)
const ctx = canvas.getContext('2d')
const loop = () => {
requestAnimationFrame(loop)
analyser.getByteTimeDomainData(waveform)
analyser.getByteFrequencyData(frequencies)
ctx.beginPath()
waveform.forEach((f, i) => ctx.lineTo(i, f))
ctx.lineTo(0,255)
frequencies.forEach((f, i) => ctx.lineTo(i, 255-f))
ctx.stroke()
}
loop()
You can see that we have two arrays of data available (I added colours for clarity):
The waveform - the raw samples of the audio being played.
The frequencies - a fourier transform of the audio passing through the node.
What’s cool about this is that you’re not tied to any specific functionality of the Web Audio API. If it’s possible for you to update something with an array of numbers, then you can just apply it to the output of the analyser node.
For instance, if we wanted to, we could definitely animate a list of emoji in time with our music.
spans.forEach(
(s, i) => s.style.transform = `scale(${1 + (frequencies[i]/100)})`
)
🔈🎤🎤🎤🎺🎷📯🎶🔊🎸🎺🎤🎸🎼🎷🎺🎻🎸🎻🎺🎸🎶🥁🎶🎵🎵🎷📯🎸🎹🎤🎷🎻🎷🔈🔊📯🎼🎤🎵🎼📯🥁🎻🎻🎤🔉🎵🎹🎸🎷🔉🔈🔉🎷🎶🔈🎸🎸🎻🎤🥁🎼📯🎸🎸🎼🎸🥁🎼🎶🎶🥁🎤🔊🎷🔊🔈🎺🔊🎻🎵🎻🎸🎵🎺🎤🎷🎸🎶🎼📯🔈🎺🎤🎵🎸🎸🔊🎶🎤🥁🎵🎹🎸🔈🎻🔉🥁🔉🎺🔊🎹🥁🎷📯🎷🎷🎤🎸🔉🎹🎷🎸🎺🎼🎤🎼🎶🎷🎤🎷📯📯🎻🎤🎷📯🎹🔈🎵🎹🎼🔊🔉🔉🔈🎶🎸🥁🎺🔈🎷🎵🔉🥁🎷🎹🎷🔊🎤🎤🔊🎤🎤🎹🎸🎹🔉🎷
Generating Audio
So far, we’ve been using the <audio> element as a source of sound.
There’s a few other sources of audio that we can use. We’ll look at the AudioBufferNode - which allows you to manually generate a sound sample, and then connect it to our graph.
First we have to create an AudioBuffer, which holds our raw data, then we pass that to an AudioBufferNode which we can then treat just like our AudioSource node. This can get a bit boring, so we’ll use a helper method that makes it simpler to generate sounds.
const generator = (audioCtx, target) => (seconds, fn) => {
const { sampleRate } = audioCtx
const buffer = audioCtx.createBuffer(
1, sampleRate * seconds, sampleRate
)
const data = buffer.getChannelData(0)
for (var i = 0; i < data.length; i++) {
data[i] = fn(i / sampleRate, seconds)
}
return () => {
const source = audioCtx.createBufferSource()
source.buffer = audioBuffer
source.connect(target || audioCtx.destination)
source.start()
}
}
const sound = generator(audioCtx, gain)
Our wrapper will let us provide a function that maps time (in seconds) to a sample (between 1 and -1). This generates a waveform, like we saw before with the analyser node.
For example, the following will generate 0.75 seconds of white noise at 20% volume.
const noise = sound(0.75, t => Math.random() * 0.2)
button.onclick = noise
Noise
Now we’ve got a noisy button! Handy.
Rather than having a static set of audio nodes, each time we click the button, we add a new node to our graph. Although this feels inefficient, it’s not actually too bad - the browser can do a good job of cleaning up old nodes once they’ve played.
An interesting property of defining sounds as functions is that we can combine multiple function to generate new sounds. So if we wanted to fade our noise in and out, we could write a higher order function that does that.
const ease = fn => (t, s) =>
fn(t) * Math.sin((t / s) * Math.PI)
const noise = sound(0.75, ease(t => Math.random() * 0.2))
ease(noise)
And we can do more than just white noise - if we use Math.sin, we can generate some nice pure tones.
// Math.sin with period of 0..1
const wave = v => Math.sin(Math.PI * 2 * v)
const hz = f => t => wave(t * f)
const _440hz = sound(0.75, ease(hz(440)))
const _880hz = sound(0.75, ease(hz(880)))
440Hz
880Hz
We can also make our functions more complex. Below we’re combining several frequencies to make a richer sounding tone.
const harmony = f => [4, 3, 2, 1].reduce(
(v, h, i) => (sin(f * h) * (i+1) ) + v
)
const a440 = sound(0.75, ease(harmony(440)))
440Hz
880Hz
Cool.
We’re still not using any audio-specific functionality, so we can repurpose anything that does an operation on data. For example, we can use d3.js - usually used for interactive data visualisations - to generate a triangular waveform.
const triangle = d3.scaleLinear()
.domain([0, .5, 1])
.range([-1, 1, -1])
const wave = t => triangle(t % 1)
const a440 = sound(0.75, ease(harmony(440)))
440Hz
880Hz
It’s pretty interesting to play around with different functions. I’ve plonked everything in jsbin if you want to have a play yourself.
A departure from best practice
We’ve been generating our audio from scratch, but most of what we’ve looked at can be implemented by a series of native Web Audio nodes. This would be way performant (because it’s not happening on the main thread), and more flexible in some ways (because you can set timings dynamically whilst the note is playing). But we’re going to stay with this approach because it’s fun, and sometimes the fun thing to do might not technically be the best thing to do.
Making a keyboard
Having a button that makes a sound is totally great, but how about lots of buttons that make lots of sounds? Yup, totally greater-er.
The first thing we need to know is the frequency of each note. I thought this would be awkward because pianos were invented more than 250 years before the Hz unit was defined, so surely there wouldn’t be a simple mapping between the two?
const freq = note => 27.5 * Math.pow(2, (note - 21) / 12)
This equation blows my mind; I’d never really figured how tightly music and maths fit together. When you see a chord or melody, you can directly map it back to a mathematical pattern.
Our keyboard is actually an SVG picture of a keyboard, so we can traverse the elements of it and map each element to a sound generated by one of the functions that we came up with before.
Array.from(svg.querySelector('rect'))
.sort((a, b) => + a.x - b.x)
.forEach((key, i) =>
key.addEventListener('touchstart',
sound(0.75, ease(harmony(freq(i + 48))))
)
)
rect {stroke: #ddd;}
rect:hover {opacity: 0.8; stroke: #000}
Et voilà. We have a keyboard.
What I like about this is that it’s completely pure - there’s no lookup tables or hardcoded attributes; we’ve just defined a mapping from SVG elements to the sound they should probably make.
Doing better in the future
As I mentioned before, this could be implemented more performantly with Web Audio nodes, or even better - use something like Tone.js to be performant for you.
Web Audio has been around for a while, though we’re getting new challenges with immersive WebXR experiences, where spatial audio becomes really important. There’s also always support and API improvements (if you like AudioBufferNode, you’re going to love AudioWorklet)
Conclusion
And that’s about it. Web Audio isn’t some black box, you can easily link it with whatever framework, or UI that you’ve built (whether you should is an entirely different question).
If anyone ever asks you “could you turn this SVG into a musical instrument?” you don’t have to stare blankly at them any more.
(function(a,c){var b=a.createElement("script");if(!("noModule"in b)&&"on"+c in b){var d=!1;a.addEventListener(c,function(a){if(a.target===b)d=!0;else if(!a.target.hasAttribute("nomodule")||!d)return;a.preventDefault()},!0);b.type="module";b.src=".";a.head.appendChild(b);b.remove()}})(document,"beforeload"); |
2017 |
Ben Foxall |
benfoxall |
2017-12-17T00:00:00+00:00 |
https://24ways.org/2017/feeding-the-audio-graph/ |
code |
| 220 |
Finding Your Way with Static Maps |
Since the introduction of the Google Maps service in 2005, online maps have taken off in a way not really possible before the invention of slippy map interaction. Although quickly followed by a plethora of similar services from both commercial and non-commercial parties, Google’s first-mover advantage, and easy-to-use developer API saw Google Maps become pretty much the de facto mapping service.
It’s now so easy to add a map to a web page, there’s no reason not to. Dropping an iframe map into your page is as simple as embedding a YouTube video.
But there’s one crucial drawback to both the solution Google provides for you to drop into your page and the code developers typically implement themselves – they don’t work without JavaScript.
A bit about JavaScript
Back in October of this year, The Yahoo! Developer Network blog ran some tests to measure how many visitors to the Yahoo! home page didn’t have JavaScript available or enabled in their browser. It’s an interesting test when you consider that the audience for the Yahoo! home page (one of the most visited pages on the web) represents about as mainstream a sample as you’ll find. If there’s any such thing as an ‘average Web user’ then this is them.
The results surprised me. It varied from region to region, but at most just two per cent of visitors didn’t have JavaScript running. To be honest, I was expecting it to be higher, but this quote from the article caught my attention:
While the percentage of visitors with JavaScript disabled seems like a low number, keep in mind that small percentages of big numbers are also big numbers.
That’s right, of course, and it got me thinking about what that two per cent means. For many sites, two per cent is the number of visitors using the Opera web browser, using IE6, or using Mobile Safari.
So, although a small percentage of the total, users without JavaScript can’t just be forgotten about, and catering for them is at the very heart of how the web is supposed to work.
Starting with content in HTML, we layer on presentation with CSS and then enhance interactivity with JavaScript. If anything fails along the way or the network craps out, or a browser just doesn’t support one of the technologies, the user still gets something they can work with.
It’s progressive enhancement – also known as doing our jobs properly.
Sorry, wasn’t this about maps?
As I was saying, the default code Google provides, and the example code it gives to developers (which typically just gets followed ‘as is’) doesn’t account for users without JavaScript. No JavaScript, no content.
When adding the ability to publish maps to our small content management system Perch, I didn’t want to provide a solution that only worked with JavaScript. I had to go looking for a way to provide maps without JavaScript, too.
There’s a simple solution, fortunately, in the form of static map tiles. All the various slippy map services use a JavaScript interface on top of what are basically rendered map image tiles. Dragging the map loads in more image tiles in the direction you want to view. If you’ve used a slippy map on a slow connection, you’ll be familiar with seeing these tiles load in one by one.
The Static Map API
The good news is that these tiles (or tiles just like them) can be used as regular images on your site. Google has a Static Map API which not only gives you a handy interface to retrieve a tile for the exact area you need, but also allows you to place pins, and zoom and centre the tile so that the image looks just so.
This means that you can create a static, non-JavaScript version of your slippy map’s initial (or ideal) state to load into your page as a regular image, and then have the JavaScript map hijack the image and make it slippy.
Clearly, that’s not going to be a perfect solution for every map’s requirements. It doesn’t allow for panning, zooming or interrogation without JavaScript. However, for the majority of straightforward map uses online, a static map makes a great alternative for those visitors without JavaScript.
Here’s the how
Retrieving a static map tile is staggeringly easy – it’s just a case of forming a URL with the correct arguments and then using that as the src of an image tag.
<img src="http://maps.google.com/maps/api/staticmap
?center=Bethlehem+Israel
&zoom=5
&size=540x280
&maptype=satellite
&markers=color:red|31.4211,35.1144
&sensor=false"
width="540" height="280" alt="Map of Bethlehem, Israel" />
As you can see, there are a few key options that we pass along to the base URL. All of these should be familiar to anyone who’s worked with the JavaScript API.
center determines the point on which the map is centred. This can be latitude and longitude values, or simply an address which is then geocoded.
zoom sets the zoom level.
size is the pixel dimensions of the image you require.
maptype can be roadmap, satellite, terrain or hybrid.
markers sets one or more pin locations. Markers can be labelled, have different colours, and so on – there’s quite a lot of control available.
sensor states whether you are using a sensor to determine the user’s location. When just embedding a map in a web page, set this to false.
There are many options, including plotting paths and setting the image format, which can all be found in the straightforward documentation.
Adding to your page
If you’ve worked with the JavaScript API, you’ll know that it needs a container element which you inject the map into:
<div id="map"></div>
All you need to do is put your static image inside that container:
<div id="map">
<img src="http://maps.google.com/maps/api/staticmap[...]" />
</div>
And then, in your JavaScript, find the image and remove it. For example, with jQuery you’d simply use:
$('#map img').remove();
Why not use a <noscript> element around the image? You could, and that would certainly work fine for browsers that do not support JavaScript. What that won’t cover, however, is the situation where the browser has JavaScript support but, for whatever reason, the JavaScript doesn’t run. This could be due to network issues, an aggressive corporate firewall, or even just a bug in your code. So for that reason, we put the image in for all browsers that show images, and then remove it when the JavaScript is successfully running.
See an example in action
About rate limits
The Google Static Map API limits the requests per site viewer – currently at one thousand distinct maps per day per viewer. So, for most sites you really don’t need to worry about the rate limit. Requests for the same tile aren’t normally counted, as the tile has already been generated and is cached. You can embed the images direct from Google and let it worry about the distribution and caching.
In conclusion
As you can see, adding a static map alongside your dynamic map for those users without JavaScript is very easy indeed. There may not be a huge percentage of web visitors browsing without JavaScript but, as we’ve seen, a small percentage of a big number is still a big number. When it’s so easy to add a static map, can you really justify not doing it? |
2010 |
Drew McLellan |
drewmclellan |
2010-12-01T00:00:00+00:00 |
https://24ways.org/2010/finding-your-way-with-static-maps/ |
code |
| 298 |
First Steps in VR |
The web is all around us. As web folk, it is our responsibility to consider the impact our work can have. Part of this includes thinking about the future; the web changes lives and if we are building the web then we are the ones making decisions that affect people in every corner of the world. I find myself often torn between wanting to make the right decisions, and just wanting to have fun. To fiddle and play. We all know how important it is to sometimes just try ideas, whether they will amount to much or not.
I think of these two mindsets as production and prototyping, though of course there are lots of overlap and phases in between. I mention this because virtual reality is currently seen as a toy for rich people, and in some ways at the moment it is. But with WebVR we are able to create interesting experiences with a relatively low entry point. I want us to have open minds, play around with things, and then see how we can use the tools we have at our disposal to make things that will help people.
Every year we see articles saying it will be the “year of virtual reality”, that was especially prevalent this year. 2016 has been a year of progress, VR isn’t quite mainstream but with efforts like Playstation VR and Google Cardboard, we are definitely seeing much more of it. This year also saw the consumer editions of the Oculus Rift and HTC Vive. So it does seem to be a good time for an overview of how to get involved with creating virtual reality on the web.
WebVR is an API for connecting to devices and retrieving continuous data such as the position and orientation. Unlike the Web Audio API and some other APIs, WebVR does not feel like a framework. You use it however you want, taking the data and using it as you wish. To make it easier, there are plenty of resources such as Three.js, A-Frame and ReactVR that help to make the heavy lifting a bit easier.
Getting Started with A-Frame
I like taking the opportunity to learn new things whenever I can. So while planning this article I thought that instead of trying to teach WebGL or even Three.js in a way that is approachable for all, I would create my first project using A-Frame and write about that. This is not a tutorial as such, I just want to show how to go about getting involved with VR. The beauty of A-Frame is that it is very similar to web components, you can just write HTML to build worlds that will automatically work on all the different types of devices. It uses WebGL and WebVR but in such a way that it quite drastically reduces the learning curve. That’s not to say you can’t build complex things, you have complete access to write JavaScript and shaders.
I’m lazy. Whenever I learn a new language or framework I have found that the best way, personally, for me to learn is to have a project and to copy the starting code from someone else. A project lets you have a good idea of what you want to produce and it means you can ignore a lot of the irrelevant documentation, focussing purely on what you need. That reduces the stress of figuring things out. Copying code also makes it easier, because you know your boilerplate code is working. There’s nothing worse than getting stuck before anything actually works the first time. So I tinker. I take code and I modify it, I play around. It’s fun.
For this project I wanted to keep things as simple as possible, so I can easily explain it without the classic “draw a circle then draw an owl”. I wrote a list of requirements, with some stretch goals that you can give a try yourself if you fancy:
Must work on Google Cardboard at a minimum, because of price
Therefore, it must not rely on having a controller
Auto-moving around a maze would be a good example
Move in direction you look
Stretch goal: Scoring, time until you hit a wall or get stuck in maze
Stretch goal: Levels, so the map doesn’t need to be random
Stretch goal: Snow!
I decided to base this project on an example, Platforms, by Don McCurdy who wrote the really useful aframe-extras. Platforms has random 3D blocks that you can jump onto, going up into the sky. So I took his code and reduced it so that the blocks are randomly spread on the ground.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>24 ways</title>
<script src="https://aframe.io/releases/0.3.2/aframe.js"></script>
<script src="//cdn.rawgit.com/donmccurdy/aframe-extras/v2.6.1/dist/aframe-extras.min.js"></script>
</head>
<body>
<a-scene>
<a-entity id="player"
camera
universal-controls
kinematic-body
position="0 1.8 0">
</a-entity>
<a-entity id="walls"></a-entity>
<a-grid id="ground" static-body></a-grid>
<a-sky id="sky" color="#AADDF0"></a-sky>
<!-- Lighting -->
<a-light type="ambient" color="#ccc"></a-light>
</a-scene>
<script>
document.querySelector('a-scene').addEventListener('render-target-loaded', function () {
var MAP_SIZE = 10,
PLATFORM_SIZE = 5,
NUM_PLATFORMS = 50;
var platformsEl = document.querySelector('#walls');
var v, box;
for (var i = 0; i < NUM_PLATFORMS; i++) {
// y: 0 is ground
v = {
x: (Math.floor(Math.random() * MAP_SIZE) - PLATFORM_SIZE) * PLATFORM_SIZE,
y: PLATFORM_SIZE / 2,
z: (Math.floor(Math.random() * MAP_SIZE) - PLATFORM_SIZE) * PLATFORM_SIZE
};
box = document.createElement('a-box');
platformsEl.appendChild(box);
box.setAttribute('color', '#39BB82');
box.setAttribute('width', PLATFORM_SIZE);
box.setAttribute('height', PLATFORM_SIZE);
box.setAttribute('depth', PLATFORM_SIZE);
box.setAttribute('position', v.x + ' ' + v.y + ' ' + v.z);
box.setAttribute('static-body', '');
}
console.info('Platforms loaded.');
});
</script>
</body>
</html>
As you can see, this is very readable. Especially if you ignore the JavaScript that is used to create the maze. A-Frame (with A-Frame Extras) gives you a lot of power with relatively little to learn. We start with an <a-scene> which is the container for everything that is going to show up on the screen. There are a few <a-entity> which can be compared to <div> as they are essentially non-semantic containers, able to be used for any purpose. The attributes are used to define functionality, for example the camera attribute sets the entity to function as a camera and kinematic-body makes it collide instead of go through objects. Attributes are also used to set position and sizes, often using JavaScript to dynamically define them.
Styling
Now we’ve got the HTML written, we need to style it. To do this we add A-Frame compatible attributes such as color and material. I recommend playing around, you can get some quite impressive effects fairly easily. Originally I wanted a light snowy maze but it ended up being dark and foggy, as I really liked the feeling it gave.
Note, you will probably need a server running for images to work. You can do this by running python -m "SimpleHTTPServer" in the folder where the code is, then go to localhost:8000 in browser.
Textures
Unless you are going for a cartoony style, you probably want to find some textures. I found some on textures.com, one image worked well for the walls and the other for the floor.
<a-assets>
<img id="texture-floor" src="floor.jpg">
<img id="texture-wall" src="wall.jpg">
</a-assets>
The <a-assets> is used to define (as well as preload and cache) all assets, including images, audio and video. As you can see, images in the Asset Management System just use normal img tags. The ids are important here as we can use them later for using the textures.
To apply a texture to an object, you create a material. For a simple material where it just shows the image, you set the src to the id selector of the image.
Replace:
<a-grid id="ground" static-body></a-grid>
With:
<a-grid id="ground" static-body material="src: #texture-floor"></a-grid>
This will automatically make the image repeat over the entire floor, in my case filling it with bricks. The walls are pretty much identical, with the slight exception that it is set in JavaScript as they are dynamically defined.
box.setAttribute('material', 'src: #texture-wall');
That’s it for the textures, for now at least. These will not look completely realistic, as the light will bump off the rectangular wall rather than texture itself. This can be improved by using maps, textures that are used to modify the shape and physical properties of the object.
Lighting
The next part of styling is lighting. By using fog and different types of lighting, we are able to add atmospheric details to the game to make it feel that bit more realistic and polished.
There are lots of types of light in A-Frame (most coming from Three.js). You can add a light either by using the <a-light> entity or by attaching a light attribute to any other entity. If there are no lights defined then A-Frame adds some by default so that the scene is always lit.
To start with I wanted to light up the scene with a general light, type="ambient", so that the whole game felt slightly dark. I chose to set the light to a reddish colour #92455E. After playing around with intensity I chose 0.4, it added enough light to get the feeling I wanted without it being overly red. I also added a blue skybox (<a-sky>), as it looked a bit odd with a white sky.
<a-light type="ambient" color="#92455E" intensity="0.4"></a-light>
<a-sky id="sky" color="#0000ff"></a-sky>
I felt that the maze looked good with a red tinge but it was a bit flat, everything was the same colour and it was a bit dark. So I added a light within the #player entity, this could have been as an attribute but I set it as a child a-light instead. By using type="point" with a high intensity and low distance, it showed close walls as being lighter. It also added a sort-of object to the player, it isn’t a walking human or anything but by moving light where the player is it feels a bit more physical.
<a-light color="#fff" distance="5" intensity="0.7" type="point"></a-light>
By this point it was starting to look decent, so I wanted to add the fog to really give some personality and depth to the maze. To do this I added the fog attribute to the <a-scene> with type=exponential so it looks thicker the further away it is and a mid intensity, so you feel a bit lost but can still see.
I was very happy with this result. It took a lot of playing around with colours and values, which is fun in itself. I highly recommend you take the code (or write your own) and play around with the numbers.
Movement
One of the reasons I decided to use aframe-extras is that it has a few different camera controls built in. As you saw earlier, I am using the universal-controls which gives WASD (keyboard) controls by default. I wanted to make it automatically move in the direction that you’re looking, but I wasn’t quite sure how without rewriting the controls. So I asked Don McCurdy for advice and he very nicely gave me a small snippet of code to get it working.
AFRAME.registerComponent('automove-controls', {
init: function () {
this.speed = 0.1;
this.isMoving = true;
this.velocityDelta = new THREE.Vector3();
},
isVelocityActive: function () {
return this.isMoving;
},
getVelocityDelta: function () {
this.velocityDelta.z = this.isMoving ? -speed : 0;
return this.velocityDelta.clone();
}
});
Replace:
universal-controls
With:
universal-controls="movementControls: automove, gamepad, keyboard"
This works by creating a component automove-controls that adds auto-move to the player without overriding movement completely. It doesn’t even touch direction, it just checks if isMoving is true then moves the player by the set speed. Components can be creating for adding all kinds of functionality with relative ease. It makes it very powerful for people of all difficulty levels.
Building a map
Currently the maze is created randomly, which is great but means there will often be walls that overlap or the player gets trapped with nowhere to go. So to solve this, I decided to use a map editor (Tiled) so that we can create the mazes ourselves. This is a great start towards one of the stretch goals, levels.
I made the maze in Tiled by finding a random tileset online (we don’t need to actually show the images), I used one tile for the wall and another for the player. Then I exported as a JavaScript file and modified it in my text editor to get rid of everything I didn’t need. I made it so 0 is the path, 1 is the wall and 2 is the player. I then added the script to the HTML, as a separate file so it’s easy to update in the future.
var map =
{
"data":[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
"height":10,
"width":10
}
As you can see, this gives a simple 10x10 maze with some dead ends. The player starts in the bottom right corner (my choice, could be anywhere). I rewrote the random platforms code (from Don’s example) to instead loop over the map data and place walls where it is 1 and position the player where data is 2. I set the position so that the origin of the map would be 0,1.5,0. The y axis is in this case the height (ground being 0), but if a wall is positioned at 0 by its centre then some of it is underground. So the y needed to be the height divided by 2.
document.querySelector('a-scene').addEventListener('render-target-loaded', function () {
var WALL_SIZE = 5,
WALL_HEIGHT = 3;
var el = document.querySelector('#walls');
var wall;
for (var x = 0; x < map.height; x++) {
for (var y = 0; y < map.width; y++) {
var i = y*map.width + x;
var position = (x-map.width/2)*WALL_SIZE + ' ' + 1.5 + ' ' + (y-map.height/2)*WALL_SIZE;
if (map.data[i] === 1) {
// Create wall
wall = document.createElement('a-box');
el.appendChild(wall);
wall.setAttribute('color', '#fff');
wall.setAttribute('material', 'src: #texture-wall;');
wall.setAttribute('width', WALL_SIZE);
wall.setAttribute('height', WALL_HEIGHT);
wall.setAttribute('depth', WALL_SIZE);
wall.setAttribute('position', position);
wall.setAttribute('static-body', ');
}
if (map.data[i] === 2) {
// Set player position
document.querySelector('#player').setAttribute('position', position);
}
}
}
console.info('Walls added.');
});
With this added, it makes it nice and easy to change around the map as well as to add new features. Perhaps you want monsters or objects. Just set the number in the map data and add an if statement to the loop. In the future you could add layers, so multiple things can be in the same position. Or perhaps even make the maze go up the y axis too, with ramps or staircases. There’s a lot you can do with relative ease. As you can see, A-Frame really does reduce the learning curve of 3D and VR on the web.
It’s Not All Fun And Games
A lot of examples of virtual reality are games, including this one. So it is understandable to think that VR is for gaming, but actually that’s just a tiny subset. There are all sorts of applications for VR, including story telling, data visualisation and even meditation.
There have been a number of cases where it has been shown virtual reality can help as a tool for therapies:
Oxford study finds virtual reality can help treat severe paranoia
Virtual Reality Therapy for Phobias at the Duke Faculty Practice
Bravemind: Virtual Reality Exposure Therapy at the University of Southern California
These are just a few examples of where virtual reality is being used around the world to help people feel better and get through some very tough times. There have also been examples of it being used for simulating war zones or medical situations, both as a teaching and journalism tool.
Wrapping Up
Ten years ago, on this very site, Cameron Moll wrote an article explaining the mobile web. He explained how mobile phones with data plans were becoming increasingly common, that WAP 2.0 included the XHTML Mobile Profile meaning it would be familiar with web folk. “The mobile web is rapidly becoming an XHTML environment, and thus you and I can apply our existing “desktop web” skills to understand how to develop content for it.”
We can look at that and laugh a little, we have come a very long way in the last decade. Even people in developing countries with very little money have mobile phones with access to a web that is far more capable than the “desktop web” Cameron was referring to.
So while I am not saying virtual reality is going to change the world or replace our phones, who knows! We can use our skills as web folk to dabble, we don’t need to learn any new languages. If on the 2026 edition of 24 ways, somebody references this article and looks at how far we have come… well, let’s hope we have used our skills well and made the world just that little bit better. And if VR is a fad? Well it’s fun… have a go anyway. |
2016 |
Shane Hudson |
shanehudson |
2016-12-11T00:00:00+00:00 |
https://24ways.org/2016/first-steps-in-vr/ |
code |
| 86 |
Flashless Animation |
Animation in a Flashless world
When I splashed down in web design four years ago, the first thing I wanted to do was animate a cartoon in the browser. I’d been drawing comics for years, and I’ve wanted to see them come to life for nearly as long. Flash animation was still riding high, but I didn’t want to learn Flash. I wanted to learn JavaScript!
Sadly, animating with JavaScript was limiting and resource-intensive. My initial foray into an infinitely looping background did more to burn a hole in my CPU than amaze my friends (although it still looks pretty cool). And there was still no simple way to incorporate audio. The browser technology just wasn’t there.
Things are different now. CSS3 transitions and animations can do most of the heavy lifting and HTML5 audio can serve up the music and audio clips. You can do a lot without leaning on JavaScript at all, and when you lean on JavaScript, you can do so much more!
In this project, I’m going to show you how to animate a simple walk cycle with looping audio. I hope this will inspire you to do something really cool and impress your friends. I’d love to see what you come up with, so please send your creations my way at rachelnabors.com!
Note: Because every browser wants to use its own prefixes with CSS3 animations, and I have neither the time nor the space to write all of them out, I will use the W3C standard syntaxes; that is, going prefix-less. You can implement them out of the box with something like Prefixfree, or you can add prefixes on your own. If you take the latter route, I recommend using Sass and Compass so you can focus on your animations, not copying and pasting.
The walk cycle
Walk cycles are the “Hello world” of animation. One of the first projects of animation students is to spend hours drawing dozens of frames to complete a simple loopable animation of a character walking.
Most animators don’t have to draw every frame themselves, though. They draw a few key frames and send those on to production animators to work on the between frames (or tween frames). This is meticulous, grueling work requiring an eye for detail and natural movement. This is also why so much production animation gets shipped overseas where labor is cheaper.
Luckily, we don’t have to worry about our frame count because we can set our own frames-per-second rate on the fly in CSS3. Since we’re trying to impress friends, not animation directors, the inconsistency shouldn’t be a problem. (Unless your friend is an animation director.)
This is a simple walk cycle I made of my comic character Tuna for my CSS animation talk at CSS Dev Conference this year:
The magic lies here:
animation: walk-cycle 1s steps(12) infinite;
Breaking those properties down:
animation: <name> <duration> <timing-function> <iteration-count>;
walk-cycle is a simple @keyframes block that moves the background sprite on .tuna around:
@keyframes walk-cycle {
0% {background-position: 0 0; }
100% {background-position: 0 -2391px;}
}
The background sprite has exactly twelve images of Tuna that complete a full walk cycle. We’re setting it to cycle through the entire sprite every second, infinitely. So why isn’t the background image scrolling down the .tuna container? It’s all down to the timing function steps(). Using steps() let us tell the CSS to make jumps instead of the smooth transitions you’d get from something like linear. Chris Mills at dev.opera wrote in his excellent intro to CSS3 animation :
Instead of giving a smooth animation throughout, [steps()] causes the animation to jump between a set number of steps placed equally along the duration. For example, steps(10) would make the animation jump along in ten equal steps. There’s also an optional second parameter that takes a value of start or end. steps(10, start) would specify that the change in property value should happen at the start of each step, while steps(10, end) means the change would come at the end.
(Seriously, go read his full article. I’m not going to touch on half the stuff he does because I cannot improve on the basics any more than he already has.)
The background
A cat walking in a void is hardly an impressive animation and certainly your buddy one cube over could do it if he chopped up some of those cat GIFs he keeps using in group chat. So let’s add a parallax background! Yes, yes, all web designers signed a peace treaty to not abuse parallax anymore, but this is its true calling—treaty be damned.
And to think we used to need JavaScript to do this! It’s still pretty CPU intensive but much less complicated. We start by splitting up the page into different layers, .foreground, .midground, and .background. We put .tuna in the .midground.
.background has multiple background images, all set to repeat horizontally:
background-image:
url(background_mountain5.png),
url(background_mountain4.png),
url(background_mountain3.png),
url(background_mountain2.png),
url(background_mountain1.png);
background-repeat: repeat-x;
With parallax, things in the foreground move faster than those in the background. Next time you’re driving, notice how the things closer to you move out of your field of vision faster than something in the distance, like a mountain or a large building. We can imitate that here by making the background images on top (in the foreground, closer to us) wider than those on the bottom of the stack (in the distance).
The different lengths let us use one animation to move all the background images at different rates in the same interval of time:
animation: parallax_bg linear 40s infinite;
The shorter images have less distance to cover in the same amount of time as the longer images, so they move slower.
Let’s have a look at the background’s animation:
@keyframes parallax_bg {
0% {
background-position: -2400px 100%, -2000px 100%, -1800px 100%, -1600px 100%, -1200px 100%;
}
100% {
background-position: 0 100%, 0 100%, 0 100%, 0 100%, 0 100%;
}
}
At 0%, all the background images are positioned at the negative value of their own widths. Then they start moving toward background-position: 0 100%. If we wanted to move them in the reverse direction, we’d remove the negative values at 0% (so they would start at 2400px 100%, 2000px 100%, etc.). Try changing the values in the codepen above or changing background-repeat to none to see how the images play together.
.foreground and .midground operate on the same principles, only they use single background images.
The music
After finishing the first draft of my original walk cycle, I made a GIF with it and posted it on YTMND with some music from the movie Paprika, specifically the track “The Girl in Byakkoya.” After showing it to some colleagues in my community, it became clear that this was a winning combination sure to drive away dresscode blues. So let’s use HTML5 to get a clip of that music looping in there!
Warning, there is sound. Please adjust your volume or apply headphones as needed.
We’re using HTML5 audio’s loop and autoplay abilities to automatically play and loop a sound file on page load:
<audio loop autoplay>
<source src="http://music.com/clip.mp3" />
</audio>
Unfortunately, you may notice there is a small pause between loops. HTML5 audio, thou art half-baked still. Let’s hope one day the Web Audio API will be able to help us out, but until things improve, we’ll have to hack our way around these shortcomings.
Turns out there’s a handy little script called seamlessLoop.js which we can use to patch this. Mind you, if we were really getting crazy with the Cheese Whiz, we’d want to get out big guns like sound.js. But that’d be overkill for a mere loop (and explaining the Web Audio API might bore, rather than impress your friends)!
Installing seamlessLoop.js will get rid of the pause, and now our walk cycle is complete.
(I’ve done some very rough sniffing to see if the browser can play MP3 files. If not, we fall back to using .ogg formatted clips (Opera and Firefox users, you’re welcome).)
Really impress your friends by adding a run cycle
So we have music, we have a walk cycle, we have parallax. It will be a snap to bring them all together and have a simple, endless animation. But let’s go one step further and knock the socks off our viewers by adding a run cycle.
The run cycle
Tacking a run cycle on to our walk cycle will require a third animation sequence: a transitional animation of Tuna switching from walking to running. I have added all these to the sprite:
Let’s work on getting that transition down. We’re going to use multiple animations on the same .tuna div, but we’re going to kick them off at different intervals using animation-delay—no JavaScript required! Isn’t that magical?
It requires a wee bit of math (not much, it doesn’t hurt) to line them up. We want to:
Loop the walk animation twice
Play the transitional cycle once (it has a finite beginning and end perfectly drawn to pick up between the last frame of the walk cycle and the first frame of the run cycle—no looping this baby)
RUN FOREVER.
Using the pattern animation: <name> <duration> <timing-function> <delay> <iteration-count>, here’s what that looks like:
animation:
walk-cycle 1s steps(12) 2,
walk-to-run .75s steps(12) 2s 1,
run-cycle .75s steps(13) 2.75s infinite;
I played with the times to get make the movement more realistic. You may notice that the running animation looks smoother than the walking animation. That’s because it has 13 keyframes running over .75 second instead of 12 running in one second. Remember, professional animation studios use super-high frame counts. This little animation isn’t even up to PBS’s standards!
The music: extended play with HTML5 audio sprites
My favorite part in the The Girl in Byakkoya is when the calm opening builds and transitions into a bouncy motif. I want to start with Tuna walking during the opening, and then loop the running and bounciness together for infinity.
The intro lasts for 24 seconds, so we set our 1 second walk cycle to run for 24 repetitions:
walk-cycle 1s steps(12) 24
We delay walk-to-run by 24 seconds so it runs for .75 seconds before…
We play run-cycle at 24.75 seconds and loop it infinitely
For the music, we need to think of it as two parts: the intro and the bouncy loop. We can do this quite nicely with audio sprites: using one HTML5 audio element and using JavaScript to change the play head location, like skipping tracks with a CD player. Although this technique will result in a small gap in music shifts, I think it’s worth using here to give you some ideas.
// Get the audio element
var byakkoya = document.querySelector('audio');
// create function to play and loop audio
function song(a){
//start playing at 0
a.currentTime = 0;
a.play();
//when we hit 64 seconds...
setTimeout(function(){
// skip back to 24.5 seconds and keep playing...
a.currentTime = 24.55;
// then loop back when we hit 64 again, or every 59.5 seconds.
setInterval(function(){
a.currentTime = 24.55;
},39450);
},64000);
}
The load screen
I’ve put it off as long as I can, but now that the music and the CSS are both running on their own separate clocks, it’s imperative that both images and music be fully downloaded and ready to run when we kick this thing off. So we need a load screen (also, it’s nice to give people a heads-up that you’re about to blast them with music, no matter how wonderful that music may be).
Since the two timers are so closely linked, we’d best not run the animations until we run the music:
* { animation-play-state: paused; }
animation-play-state can be set to paused or running, and it’s the most useful thing you will learn today.
First we use an event listener to see when the browser thinks we can play through from the beginning to end of the music without pause for buffering:
byakkoya.addEventListener("canplaythrough", function () { });
(More on HTML5 audio’s media events at HTML5doctor.com)
Inside our event listener, I use a bit of jQuery to add class of .playable to the body when we’re ready to enable the play button:
$("body").addClass("playable");
$("#play-me").html("Play me.").click(function(){
song(byakkoya);
$("body").addClass("playing");
});
That .playing class is special because it turns on the animations at the same time we start playing the song:
.playing * { animation-play-state: running; }
The background
We’re almost done here! When we add the background, it needs to speed up at the same time that Tuna starts running. The music picks up speed around 24.75 seconds in, and so we’re going to use animation-delay on those backgrounds, too.
This will require some math. If you try to simply shorten the animation’s duration at the 24.75s mark, the backgrounds will, mid-scroll, jump back to their initial background positions to start the new animation! Argh! So let’s make a new @keyframe and calculate where the background position would be just before we speed up the animation.
Here’s the formula:
new 0% value = delay ÷ old duration × length of image
new 100% value = new 0% value + length of image
Here’s the formula put to work on a smaller scale:
Voilà! The finished animation!
I’ve always wanted to bring my illustrations to life. Then I woke up one morning and realized that I had all the tools to do so in my browser and in my head. Now I have fallen in love with Flashless animation.
I’m sure there will be detractors who say HTML wasn’t meant for this and it’s a gross abuse of the DOM! But I say that these explorations help us expand what we expect from devices and software and challenge us in good ways as artists and programmers. The browser might not be the most appropriate place for animation, but is certainly a fun place to start.
There is so much you can do with the spec implemented today, and so much of the territory is still unexplored. I have not yet begun to show you everything. In eight months I expect this demo will represent the norm, not the bleeding edge. I look forward to seeing the wonderful things you create.
(Also, someone, please, do something about that gappy HTML5 audio looping. It’s a crying shame!) |
2012 |
Rachel Nabors |
rachelnabors |
2012-12-06T00:00:00+00:00 |
https://24ways.org/2012/flashless-animation/ |
code |
| 139 |
Flickr Photos On Demand with getFlickr |
In case you don’t know it yet, Flickr is great. It is a lot of fun to upload, tag and caption photos and it is really handy to get a vast network of contacts through it.
Using Flickr photos outside of it is a bit of a problem though. There is a Flickr API, and you can get almost every page as an RSS feed, but in general it is a bit tricky to use Flickr photos inside your blog posts or web sites. You might not want to get into the whole API game or use a server side proxy script as you cannot retrieve RSS with Ajax because of the cross-domain security settings.
However, Flickr also provides an undocumented JSON output, that can be used to hack your own solutions in JavaScript without having to use a server side script.
If you enter the URL http://flickr.com/photos/tags/panda you get to the flickr page with photos tagged “panda”.
If you enter the URL http://api.flickr.com/services/feeds/photos_public.gne?tags=panda&format=rss_200 you get the same page as an RSS feed.
If you enter the URL http://api.flickr.com/services/feeds/photos_public.gne?tags=panda&format=json you get a JavaScript function called jsonFlickrFeed with a parameter that contains the same data in JSON format
You can use this to easily hack together your own output by just providing a function with the same name. I wanted to make it easier for you, which is why I created the helper getFlickr for you to download and use.
getFlickr for Non-Scripters
Simply include the javascript file getflickr.js and the style getflickr.css in the head of your document:
<script type="text/javascript" src="getflickr.js"></script>
<link rel="stylesheet" href="getflickr.css" type="text/css">
Once this is done you can add links to Flickr pages anywhere in your document, and when you give them the CSS class getflickrphotos they get turned into gallery links. When a visitor clicks these links they turn into loading messages and show a “popup” gallery with the connected photos once they were loaded. As the JSON returned is very small it won’t take long. You can close the gallery, or click any of the thumbnails to view a photo. Clicking the photo makes it disappear and go back to the thumbnails.
Check out the example page and click the different gallery links to see the results.
Notice that getFlickr works with Unobtrusive JavaScript as when scripting is disabled the links still get to the photos on Flickr.
getFlickr for JavaScript Hackers
If you want to use getFlickr with your own JavaScripts you can use its main method leech():
getFlickr.leech(sTag, sCallback);
sTag
the tag you are looking for
sCallback
an optional function to call when the data was retrieved.
After you called the leech() method you have two strings to use:
getFlickr.html[sTag]
contains an HTML list (without the outer UL element) of all the images linked to the correct pages at flickr. The images are the medium size, you can easily change that by replacing _m.jpg with _s.jpg for thumbnails.
getFlickr.tags[sTag]
contains a string of all the other tags flickr users added with the tag you searched for(space separated)
You can call getFlickr.leech() several times when the page has loaded to cache several result feeds before the page gets loaded. This’ll make the photos quicker for the end user to show up. If you want to offer a form for people to search for flickr photos and display them immediately you can use the following HTML:
<form onsubmit="getFlickr.leech(document.getElementById('tag').value, 'populate');return false">
<label for="tag">Enter Tag</label>
<input type="text" id="tag" name="tag" />
<input type="submit" value="energize" />
<h3>Tags:</h3><div id="tags"></div>
<h3>Photos:</h3><ul id="photos"></ul>
</form>
All the JavaScript you’ll need (for a basic display) is this:
function populate(){
var tag = document.getElementById('tag').value;
document.getElementById('photos').innerHTML = getFlickr.html[tag].replace(/_m\.jpg/g,'_s.jpg');
document.getElementById('tags').innerHTML = getFlickr.tags[tag];
return false;
}
Easy as pie, enjoy!
Check out the example page and try the form to see the results. |
2006 |
Christian Heilmann |
chrisheilmann |
2006-12-03T00:00:00+00:00 |
https://24ways.org/2006/flickr-photos-on-demand/ |
code |
| 175 |
Front-End Code Reusability with CSS and JavaScript |
Most web standards-based developers are more than familiar with creating their sites with semantic HTML with lots and lots of CSS. With each new page in a design, the CSS tends to grow and grow and more elements and styles are added. But CSS can be used to better effect.
The idea of object-oriented CSS isn’t new. Nicole Sullivan has written a presentation on the subject and outlines two main concepts: separate structure and visual design; and separate container and content. Jeff Croft talks about Applying OOP Concepts to CSS:
I can make a class of .box that defines some basic layout structure, and another class of .rounded that provides rounded corners, and classes of .wide and .narrow that define some widths, and then easily create boxes of varying widths and styles by assigning multiple classes to an element, without having to duplicate code in my CSS.
This concept helps reduce CSS file size, allows for great flexibility, rapid building of similar content areas and means greater consistency throughout the entire design. You can also take this concept one step further and apply it to site behaviour with JavaScript.
Build a versatile slideshow
I will show you how to build multiple slideshows using jQuery, allowing varying levels of functionality which you may find on one site design. The code will be flexible enough to allow you to add previous/next links, image pagination and the ability to change the animation type. More importantly, it will allow you to apply any combination of these features.
Image galleries are simply a list of images, so the obvious choice of marking the content up is to use a <ul>. Many designs, however, do not cater to non-JavaScript versions of the website, and thus don’t take in to account large multiple images. You could also simply hide all the other images in the list, apart from the first image. This method can waste bandwidth because the other images might be downloaded when they are never going to be seen.
Taking this second concept — only showing one image — the only code you need to start your slideshow is an <img> tag. The other images can be loaded dynamically via either a per-page JavaScript array or via AJAX.
The slideshow concept is built upon the very versatile Cycle jQuery Plugin and is structured in to another reusable jQuery plugin. Below is the HTML and JavaScript snippet needed to run every different type of slideshow I have mentioned above.
<img src="path/to/image.jpg" alt="About the image" title="" height="250" width="400" class="slideshow">
<script type="text/javascript">
jQuery().ready(function($) {
$('img.slideshow').slideShow({
images: ['1.jpg', '2.jpg', '3.jpg']
});
});
</script>
Slideshow plugin
If you’re not familiar with jQuery or how to write and author your own plugin there are plenty of articles to help you out.
jQuery has a chainable interface and this is something your plugin must implement. This is easy to achieve, so your plugin simply returns the collection it is using:
return this.each(
function () {}
};
Local Variables
To keep the JavaScript clean and avoid any conflicts, you must set up any variables which are local to the plugin and should be used on each collection item. Defining all your variables at the top under one statement makes adding more and finding which variables are used easier. For other tips, conventions and improvements check out JSLint, the “JavaScript Code Quality Tool”.
var $$, $div, $images, $arrows, $pager,
id, selector, path, o, options,
height, width,
list = [], li = 0,
parts = [], pi = 0,
arrows = ['Previous', 'Next'];
Cache jQuery Objects
It is good practice to cache any calls made to jQuery. This reduces wasted DOM calls, can improve the speed of your JavaScript code and makes code more reusable.
The following code snippet caches the current selected DOM element as a jQuery object using the variable name $$. Secondly, the plugin makes its settings available to the Metadata plugin‡ which is best practice within jQuery plugins.
For each slideshow the plugin generates a <div> with a class of slideshow and a unique id. This is used to wrap the slideshow images, pagination and controls.
The base path which is used for all the images in the slideshow is calculated based on the existing image which appears on the page. For example, if the path to the image on the page was /img/flowers/1.jpg the plugin would use the path /img/flowers/ to load the other images.
$$ = $(this);
o = $.metadata ? $.extend({}, settings, $$.metadata()) : settings;
id = 'slideshow-' + (i++ + 1);
$div = $('<div />').addClass('slideshow').attr('id', id);
selector = '#' + id + ' ';
path = $$.attr('src').replace(/[0-9]\.jpg/g, '');
options = {};
height = $$.height();
width = $$.width();
Note: the plugin uses conventions such as folder structure and numeric filenames. These conventions help with the reusable aspect of plugins and best practices.
Build the Images
The cycle plugin uses a list of images to create the slideshow. Because we chose to start with one image we must now build the list programmatically. This is a case of looping through the images which were added via the plugin options, building the appropriate HTML and appending the resulting <ul> to the DOM.
$.each(o.images, function () {
list[li++] = '<li>';
list[li++] = '<img src="' + path + this + '" height="' + height + '" width="' + width + '">';
list[li++] = '</li>';
});
$images = $('<ul />').addClass('cycle-images');
$images.append(list.join('')).appendTo($div);
Although jQuery provides the append method it is much faster to create one really long string and append it to the DOM at the end.
Update the Options
Here are some of the options we’re making available by simply adding classes to the <img>. You can change the slideshow effect from the default fade to the sliding effect. By adding the class of stopped the slideshow will not auto-play and must be controlled via pagination or previous and next links.
// different effect
if ($$.is('.slide')) {
options.fx = 'scrollHorz';
}
// don't move by default
if ($$.is('.stopped')) {
options.timeout = 0;
}
If you are using the same set of images throughout a website you may wish to start on a different image on each page or section. This can be easily achieved by simply adding the appropriate starting class to the <img>.
// based on the class name on the image
if ($$.is('[class*=start-]')) {
options.startingSlide = parseInt($$.attr('class').replace(/.*start-([0-9]+).*/g, "$1"), 10) - 1;
}
For example:
<img src="/img/slideshow/3.jpg" alt="About the image" title="" height="250" width="400" class="slideshow start-3">
By default, and without JavaScript, the third image in this slideshow is shown. When the JavaScript is applied to the page the slideshow must know to start from the correct place, this is why the start class is required.
You could capture the default image name and parse it to get the position, but only the default image needs to be numeric to work with this plugin (and could easily be changed in future). Therefore, this extra specifically defined option means the plugin is more tolerant.
Previous/Next Links
A common feature of slideshows is previous and next links enabling the user to manually progress the images. The Cycle plugin supports this functionality, but you must generate the markup yourself. Most people add these directly in the HTML but normally only support their behaviour when JavaScript is enabled. This goes against progressive enhancement. To keep with the best practice progress enhancement method the previous/next links should be generated with JavaScript.
The follow snippet checks whether the slideshow requires the previous/next links, via the arrows class. It restricts the Cycle plugin to the specific slideshow using the selector we created at the top of the plugin. This means multiple slideshows can run on one page without conflicting each other.
The code creates a <ul> using the arrows array we defined at the top of the plugin. It also adds a class to the slideshow container, meaning you can style different combinations of options in your CSS.
// create the arrows
if ($$.is('.arrows') && list.length > 1) {
options.next = selector + '.next';
options.prev = selector + '.previous';
$arrows = $('<ul />').addClass('cycle-arrows');
$.each(arrows, function (i, val) {
parts[pi++] = '<li class="' + val.toLowerCase() + '">';
parts[pi++] = '<a href="#' + val.toLowerCase() + '">';
parts[pi++] = '<span>' + val + '</span>';
parts[pi++] = '</a>';
parts[pi++] = '</li>';
});
$arrows.append(parts.join('')).appendTo($div);
$div.addClass('has-cycle-arrows');
}
The arrow array could be placed inside the plugin settings to allow for localisation.
Pagination
The Cycle plugin creates its own HTML for the pagination of the slideshow. All our plugin needs to do is create the list and selector to use. This snippet creates the pagination container and appends it to our specific slideshow container. It sets the Cycle plugin pager option, restricting it to the specific slideshow using the selector we created at the top of the plugin. Like the previous/next links, a class is added to the slideshow container allowing you to style the slideshow itself differently.
// create the clickable pagination
if ($$.is('.pagination') && list.length > 1) {
options.pager = selector + '.cycle-pagination';
$pager = $('<ul />').addClass('cycle-pagination');
$pager.appendTo($div);
$div.addClass('has-cycle-pagination');
}
Note: the Cycle plugin creates a <ul> with anchors listed directly inside without the surrounding <li>. Unfortunately this is invalid markup but the code still works.
Demos
Well, that describes all the ins-and-outs of the plugin, but demos make it easier to understand! Viewing the source on the demo page shows some of the combinations you can create with a simple <img>, a few classes and some thought-out JavaScript.
View the demos →
Decide on defaults
The slideshow plugin uses the exact same settings as the Cycle plugin, but some are explicitly set within the slideshow plugin when using the classes you have set.
When deciding on what functionality is going to be controlled via this class method, be careful to choose your defaults wisely. If all slideshows should auto-play, don’t make this an option — make the option to stop the auto-play. Similarly, if every slideshow should have previous/next functionality make this the default and expose the ability to remove them with a class such as “no-pagination”.
In the examples presented on this article I have used a class on each <img>. You can easily change this to anything you want and simply apply the plugin based on the jQuery selector required.
Grab your images
If you are using AJAX to load in your images, you can speed up development by deciding on and keeping to a folder structure and naming convention. There are two methods: basing the image path based on the current URL; or based on the src of the image. The first allows a different slideshow on each page, but in many instances a site will have a couple of sets of images and therefore the second method is probably preferred.
Metadata ‡
A method which allows you to directly modify settings in certain plugins, which also uses the classes from your HTML already exists. This is a jQuery plugin called Metadata. This method allows for finer control over the plugin settings themselves. Some people, however, may dislike the syntax and prefer using normal classes, like above which when sprinkled with a bit more JavaScript allows you to control what you need to control.
The takeaway
Hopefully you have understood not only what goes in to a basic jQuery plugin but also learnt a new and powerful idea which you can apply to other areas of your website.
The idea can also be applied to other common interfaces such as lightboxes or mapping services such as Google Maps — for example creating markers based on a list of places, each with different pin icons based the anchor class. |
2009 |
Trevor Morris |
trevormorris |
2009-12-06T00:00:00+00:00 |
https://24ways.org/2009/front-end-code-reusability-with-css-and-javascript/ |
code |
| 289 |
Front-End Developers Are Information Architects Too |
The theme of this year’s World IA Day was “Information Everywhere, Architects Everywhere”. This article isn’t about what you may consider an information architect to be: someone in the user-experience field, who maybe studied library science, and who talks about taxonomies. This is about a realisation I had a couple of years ago when I started to run an increasing amount of usability-testing sessions with people who have disabilities: that the structure, labelling, and connections that can be made in front-end code is information architecture. People’s ability to be successful online is unequivocally connected to the quality of the code that is written.
Places made of information
In information architecture we talk about creating places made of information. These places are made of ones and zeros, but we talk about them as physical structures. We talk about going onto a social media platform, posting in blogs, getting locked out of an environment, and building applications. In 2002, Andrew Hinton stated:
People live and work in these structures, just as they live and work in their homes, offices, factories and malls. These places are not virtual: they are as real as our own minds.
25 Theses
We’re creating structures which people rely on for significant parts of their lives, so it’s critical that we carry out our work responsibly. This means we must use our construction materials correctly. Luckily, our most important material, HTML, has a well-documented specification which tells us how to build robust and accessible places. What is most important, I believe, is to understand the semantics of HTML.
Semantics
The word “semantic” has its origin in Greek words meaning “significant”, “signify”, and “sign”. In the physical world, a structure can have semantic qualities that tell us something about it. For example, the stunning Westminster Abbey inspires awe and signifies much about the intent and purpose of the structure. The building’s size; the quality of the stone work; the massive, detailed stained glass: these are all signs that this is a building meant for something the creators deemed important. Alternatively consider a set of large, clean, well-positioned, well-lit doors on the ground floor of an office block: they don’t need an “entrance” sign to communicate their use and to stop people trying to use a nearby fire exit to get into the building. The design of the doors signify their usage. Sometimes a more literal and less awe-inspiring approach to communicating a building’s purpose happens, but the affect is similar: the building is signifying something about its purpose.
HTML has over 115 elements, many of which have semantics to signify structure and affordance to people, browsers, and assistive technology. The HTML 5.1 specification mentions semantics, stating:
Elements, attributes, and attribute values in HTML are defined … to have certain meanings (semantics). For example, the <ol> element represents an ordered list, and the lang attribute represents the language of the content.
HTML 5.1 Semantics, structure, and APIs of HTML documents
HTML’s baked-in semantics means that developers can architect their code to signify structure, create relationships between elements, and label content so people can understand what they’re interacting with. Structuring and labelling information to make it available, usable, and understandable to people is what an information architect does. It’s also what a front-end developer does, whether they realise it or not.
A brief introduction to information architecture
We’re going to start by looking at what an information architect is. There are many definitions, and I’m going to quote Richard Saul Wurman, who is widely regarded as the father of information architecture. In 1976 he said an information architect is:
the individual who organizes the patterns inherent in data, making the complex clear; a person who creates the structure or map of information which allows others to find their personal paths to knowledge; the emerging 21st century professional occupation addressing the needs of the age focused upon clarity, human understanding, and the science of the organization of information.
Of Patterns And Structures
To me, this clearly defines any developer who creates code that a browser, or other user agent (for example, a screen reader), uses to create a structured, navigable place for people.
Just as there are many definitions of what an information architect is, there are for information architecture itself. I’m going to use the definition from the fourth edition of Information Architecture For The World Wide Web, in which the authors define it as:
The structural design of shared information environments.
The synthesis of organization, labeling, search, and navigation systems within digital, physical, and cross-channel ecosystems.
The art and science of shaping information products and experiences to support usability, findability, and understanding.
Information Architecture For The World Wide Web, 4th Edition
To me, this describes front-end development. Done properly, there is an art to creating robust, accessible, usable, and findable spaces that delight all our users. For example, at 2015’s State Of The Browser conference, Edd Sowden talked about the accessibility of <table>s. He discovered that by simply not using the semantically-correct <th> element to mark up <table> headings, in some situations browsers will decide that a <table> is being used for layout and essentially make it invisible to assistive technology. Another example of how coding practices can affect the usability and findability of content is shown by Léonie Watson in her How ARIA landmark roles help screen reader users video. By using ARIA landmark roles, people who use screen readers are quickly able to identify and jump to common parts of a web page.
Our definitions of information architects and information architecture mention patterns, rules, organisation, labelling, structure, and relationships. There are numerous different models for how these elements get boiled down to their fundamentals. In his Understanding Context book, Andrew Hinton calls them Labels, Relationships, and Rules; Jorge Arango calls them Links, Nodes, And Order; and Dan Klyn uses Ontology, Taxonomy, and Choreography, which is the one we’re going to use. Dan defines these terms as:
Ontology
The definition and articulation of the rules and patterns that govern the meaning of what we intend to communicate.
What we mean when we say what we say.
Taxonomy
The arrangements of the parts. Developing systems and structures for what everything’s called, where everything’s sorted, and the relationships between labels and categories
Choreography
Rules for interaction among the parts. The structures it creates foster specific types of movement and interaction; anticipating the way users and information want to flow and making affordance for change over time.
We now have definitions of an information architect, information architecture, and a model of the elements of information architecture. But is writing HTML really creating information or is it just wrangling data and metadata? When does data turn into information? In his book Managing For The Future Peter Drucker states:
… data is not information. Information is data endowed with relevance and purpose.
Managing For The Future
If we use the correct semantic element to mark up content then we’re developing with purpose and creating relevance. For example, if we follow the advice of the HTML 5.1 specification and mark up headings using heading rank instead of the outline algorithm, we’re creating a structure where the depth of one heading is relevant to the previous one. Architected correctly, an <h2> element should be relevant to its parent, which should be the <h1>. By following the HTML specification we can create a structured, searchable, labeled document that will hopefully be relevant to what our users need to be successful. If you’ve never used a screen reader, you might be wondering how the headings on a page are searchable. Screen readers give users the ability to interact with headings in a couple of ways:
by creating a list of headings so users can quickly scan the page for information
by using a keyboard command to cycle through one heading at a time
If we had a document for Christmas Day TV we might structure it something like this:
<h1>Christmas Day TV schedule</h1>
<h2>BBC1</h2>
<h3>Morning</h3>
<h3>Evening</h3>
<h2>BBC2</h2>
<h3>Morning</h3>
<h3>Evening</h3>
<h2>ITV</h2>
<h3>Morning</h3>
<h3>Evening</h3>
<h2>Channel 4</h2>
<h3>Morning</h3>
<h3>Evening</h3>
If I use VoiceOver to generate a list of headings, I get this:
Once I have that list I can use keyboard commands to filter the list based on the heading level. For example, I can press 2 to hear just the <h2>s:
If we hadn’t used headings, of if we’d nested them incorrectly, our users would be frustrated.
Putting this together
Let’s put this together with an example of a button that, when pressed, toggles the appearance of a panel of links. There are numerous ways we could create a button on a web page, but the best way is to just use a <button>. Every browser understands what a <button> is, how it works, and what keyboard shortcuts should be used with them. The HTML specification for the <button> element says:
The <button> element represents a button labeled by its contents.
The contents that a <button> can have include the type attribute, any relevant ARIA attributes, and the actual text label that the user sees. This information is more important than the visual design: it doesn’t matter how beautiful or obtuse the design is, if the underlying code is non-semantic and poorly labelled, people are going to struggle to use it. Here are three buttons, each created with the same HTML but with different designs:
Regardless of what they look like, because we’ve used semantic HTML instead of a bunch of meaningless <div>s or <span>s, people who use assistive technology are going to benefit. Out of the box, without any extra development effort, a <button> is accessible and usable with a keyboard. We don’t have to write event handlers to listen for people pressing the Enter key or the space bar, which we would have to do if we’d faked a button with non-semantic elements. Our <button> can also be quickly findable: for example, in the same way it’s possible to create a list of headings with a screen reader, I can also create a list of form elements and then quickly jump to the one I want.
Now we have our <button>, let’s add the panel we’re toggling the appearance of. Here’s our code:
<button aria-controls="panel" aria-expanded="false" class="settings" id="settings" type="button">Settings</button>
<div class="panel hidden" id="panel">
<ul aria-labelledby="settings">
<li><a href="…">Account</a></li>
<li><a href="…">Privacy</a></li>
<li><a href="…">Security</a></li>
</ul>
</div>
There’s quite a bit going on here. We’re using the:
aria-controls attribute to architect a connection between the <button> element and the panel whose appearance it controls. When some assistive technology, for example the JAWS screen reader, encounters an element with aria-controls it audibly tells a user about the controlled expanded element and gives them the ability to move focus to it.
aria-expanded attribute to denote whether the panel is visible or not. We toggle this value using JavaScript to true when the panel is visible and false when it’s not. This important attribute tells people who use screen readers about the state of the elements they’re interacting with. For example, VoiceOver announces Settings expanded button when the panel is visible and Settings collapsed button when it’s hidden.
aria-labelledby attribute to give the list a title of “Settings”. This can benefit some users of assistive technology. For example, screen readers can cycle through all the lists on a page, so being able to title them can improve findability. Being able to hear list Settings three items is, I’d argue, more useful than list three items. By doing this we’re supporting usability and findability.
<ul> element to contain our list of links in our panel.
Let’s look at the choice of <ul> to contain our settings choices. Firstly, our settings are related items, so they belong in a structure that semantically groups things. This is something that a list can do that other elements or patterns can’t. This pattern, for example, isn’t semantic and has no structure:
<div><a href="…">Account</a></div>
<div><a href="…">Privacy</a></div>
<div><a href="…">Security</a></div>
All we have there is three elements next to each other on the screen and in the DOM. That is not robust code that signifies anything.
Why are we using an unordered list as opposed to an ordered list or a definition list? A quick look at the HTML specification tells us why:
The <ul> element represents a list of items, where the order of the items is not important — that is, where changing the order would not materially change the meaning of the document.
The HTML 5.1 specification’s description of the element
Will the meaning of our document materially change if we moved the order of our links around? Nope. Therefore, I’d argue, we’ve used the correct element to structure our content.
These coding decisions are information architecture
I believe that what we’ve done here is pure information architecture. Going back to Dan Klyn’s model, we’ve practiced ontology by looking at the meaning of what we’re intending to communicate:
we want to communicate there is an interactive element that toggles the appearance of an element on a page so we’ve used one, a <button>, with those semantics.
programmatically we’ve used the type='button' attribute to signify that the button isn’t a menu, reset, or submit element.
visually we’ve designed our <button> look like something that can be interacted with and, importantly, we haven’t removed the focus ring.
we’ve labelled the <button> with the word “Settings” so that our users will hopefully understand what the button is for.
we’ve used an <ul> element to structure and communicate our list of related items.
We’ve also practiced taxonomy by developing systems and structures and creating relationships between our elements:
by connecting the <button> to the panel using the aria-controls attribute we’ve programmatically created a relationship between two elements.
we’ve developed a structure in our elements by labelling our <ul> with the same name as the <button> that controls its appearance.
And finally we’ve practiced choreography by creating elements that foster movement and interaction. We’ve anticipated the way users and information want to flow:
we’ve used a <button> element that is interactive and accessible out of the box.
our aria-controls attribute can help some people who use screen readers move easily from the <button> to the panel it controls.
by toggling the value of the aria-expanded attribute we’ve developed a system that tells assistive technology about the status of the relationship between our elements: the panel is visible or the panel is hidden.
we’ve made sure our information is more usable and findable no matter how our users want or need to interact with it. Regardless of how someone “sees” our work they’re going to be able to use it because we’ve architected multiple ways to access our information.
Information architecture, robust code, and accessibility
The United Nations estimates that around 10% of the world’s population has some form of disability which, at the time of writing, is around 740,000,000 people. That’s a lot of people who rely on well-architected semantic code that can be interpreted by whatever assistive technology they may need to use.
If everyone involved in the creation of our places made of information practiced information architecture it would make satisfying the WCAG 2.0 POUR principles so much easier. Our digital construction practices directly affect the quality of life of millions of people, and we have a responsibility to make technology available to them. In her book How To Make Sense Of Any Mess, Abby Covert states:
If we’re going to be successful in this new world, we need to see information as a workable material and learn to architect it in a way that gets us to our goals.
How To Make Sense Of Any Mess
I believe that the world will be a better place if we start treating front-end development as information architecture. |
2016 |
Francis Storr |
francisstorr |
2016-12-17T00:00:00+00:00 |
https://24ways.org/2016/front-end-developers-are-information-architects-too/ |
code |
| 109 |
Geotag Everywhere with Fire Eagle |
A note from the editors: Since this article was written Yahoo! has retired the Fire Eagle service.
Location, they say, is everywhere. Everyone has one, all of the time. But on the web, it’s taken until this year to see the emergence of location in the applications we use and build.
The possibilities are broad. Increasingly, mobile phones provide SDKs to approximate your location wherever you are, browser extensions such as Loki and Mozilla’s Geode provide browser-level APIs to establish your location from the proximity of wireless networks to your laptop. Yahoo’s Brickhouse group launched Fire Eagle, an ambitious location broker enabling people to take their location from any of these devices or sources, and provide it to a plethora of web services. It enables you to take the location information that only your iPhone knows about and use it anywhere on the web.
That said, this is still a time of location as an emerging technology. Fire Eagle stores your location on the web (protected by application-specific access controls), but to try and give an idea of how useful and powerful your location can be — regardless of the services you use now — today’s 24ways is going to build a bookmarklet to call up your location on demand, in any web application.
Location Support on the Web
Over the past year, the number of applications implementing location features has increased dramatically. Plazes and Brightkite are both full featured social networks based around where you are, whilst Pownce rolled in Fire Eagle support to allow geotagging of all the content you post to their microblogging service. Dipity’s beautiful timeline shows for you moving from place to place and Six Apart’s activity stream for Movable Type started exposing your movements.
The number of services that hook into Fire Eagle will increase as location awareness spreads through the developer community, but you can use your location on other sites indirectly too.
Consider Flickr. Now world renowned for their incredible mapping and places features, geotagging on Flickr started out as a grassroots extension of regular tagging. That same technique can be used to start rolling geotagging in any publishing platform you come across, for any kind of content. Machine-tags (geo:lat= and geo:lon=) and the adr and geo microformats can be used to enhance anything you write with location information.
A crash course in avian inflammability
Fire Eagle is a location store. A broker between services and devices which provide location and those which consume it. It’s a switchboard that controls which pieces of your location different applications can see and use, and keeps hidden anything you want kept private. A blog widget that displays your current location in public can be restricted to display just your current city, whilst a service that provides you with a list of the nearest ATMs will operate better with a precise street address.
Even if your iPhone tells Fire Eagle exactly where you are, consuming applications only see what you want them to see. That’s important for users to realise that they’re in control, but also important for application developers to remember that you cannot rely on having super-accurate information available all the time. You need to build location aware applications which degrade gracefully, because users will provide fuzzier information — either through choice, or through less accurate sources.
Application specific permissions are controlled through an OAuth API. Each application has a unique key, used to request a second, user-specific key that permits access to that user’s information. You store that user key and it remains valid until such a time as the user revokes your application’s access. Unlike with passwords, these keys are unique per application, so revoking the access rights of one application doesn’t break all the others.
Building your first Fire Eagle app; Geomarklet
Fire Eagle’s developer documentation can take you through examples of writing simple applications using server side technologies (PHP, Python). Here, we’re going to write a client-side bookmarklet to make your location available in every site you use. It’s designed to fast-track the experience of having location available everywhere on web, and show you how that can be really handy. Hopefully, this will set you thinking about how location can enhance the new applications you build in 2009.
An oddity of bookmarklets
Bookmarklets (or ‘favlets’, for those of an MSIE persuasion) are a strange environment to program in. Critically, you have no persistent storage available. As such, using token-auth APIs in a static environment requires you to build you application in a slightly strange way; authing yourself in advance and then hardcoding the keys into your script.
Get started
Before you do anything else, go to http://fireeagle.com and log in, get set up if you need to and by all means take a look around. Take a look at the mobile updaters section of the application gallery and perhaps pick out an app that will update Fire Eagle from your phone or laptop.
Once that’s done, you need to register for an application key in the developer section. Head straight to /developer/create and complete the form. Since you’re building a standalone application, choose ‘Auth for desktop applications’ (rather than web applications), and select that you’ll be ‘accessing location’, not updating.
At the end of this process, you’ll have two application keys, a ‘Consumer Key’ and a ‘Consumer Secret’, which look like these:
Consumer Key
luKrM9U1pMnu
Consumer Secret
ZZl9YXXoJX5KLiKyVrMZffNEaBnxnd6M
These keys combined allow your application to make requests to Fire Eagle.
Next up, you need to auth yourself; granting your new application permission to use your location. Because bookmarklets don’t have local storage, you can’t integrate the auth process into the bookmarklet itself — it would have no way of storing the returned key. Instead, I’ve put together a simple web frontend through which you can auth with your application.
Head to Auth me, Amadeus!, enter the application keys you just generated and hit ‘Authorize with Fire Eagle’. You’ll be taken to the Fire Eagle website, just as in regular Fire Eagle applications, and after granting access to your app, be redirected back to Amadeus which will provide you your user tokens. These tokens are used in subsequent requests to read your location.
And, skip to the end…
The process of building the bookmarklet, making requests to Fire Eagle, rendering it to the page and so forth follows, but if you’re the impatient type, you might like to try this out right now. Take your four API keys from above, and drag the following link to your Bookmarks Toolbar; it contains all the code described below. Before you can use it, you need to edit in your own API keys. Open your browser’s bookmark editor and where you find text like ‘YOUR_CONSUMER_KEY_HERE’, swap in the corresponding key you just generated.
Get Location
Bookmarklet Basics
To start on the bookmarklet code, set out a basic JavaScript module-pattern structure:
var Geomarklet = function() {
return ({
callback: function(json) {},
run: function() {}
});
};
Geomarklet.run();
Next we’ll add the keys obtained in the setup step, and also some basic Fire Eagle support objects:
var Geomarklet = function() {
var Keys = {
consumer_key: 'IuKrJUHU1pMnu',
consumer_secret: 'ZZl9YXXoJX5KLiKyVEERTfNEaBnxnd6M',
user_token: 'xxxxxxxxxxxx',
user_secret: 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
};
var LocationDetail = {
EXACT: 0,
POSTAL: 1,
NEIGHBORHOOD: 2,
CITY: 3,
REGION: 4,
STATE: 5,
COUNTRY: 6
};
var index_offset;
return ({
callback: function(json) {},
run: function() {}
});
};
Geomarklet.run();
The Location Hierarchy
A successful Fire Eagle query returns an object called the ‘location hierarchy’. Depending on the level of detail shared, the index of a particular piece of information in the array will vary. The LocationDetail object maps the array indices of each level in the hierarchy to something comprehensible, whilst the index_offset variable is an adjustment based on the detail of the result returned.
The location hierarchy object looks like this, providing a granular breakdown of a location, in human consumable and machine-friendly forms.
"user": {
"location_hierarchy": [{
"level": 0,
"level_name": "exact",
"name": "707 19th St, San Francisco, CA",
"normal_name": "94123",
"geometry": {
"type": "Point",
"coordinates": [ - 0.2347530752, 67.232323]
},
"label": null,
"best_guess": true,
"id": ,
"located_at": "2008-12-18T00:49:58-08:00",
"query": "q=707%2019th%20Street,%20Sf"
},
{
"level": 1,
"level_name": "postal",
"name": "San Francisco, CA 94114",
"normal_name": "12345",
"woeid": ,
"place_id": "",
"geometry": {
"type": "Polygon",
"coordinates": [],
"bbox": []
},
"label": null,
"best_guess": false,
"id": 59358791,
"located_at": "2008-12-18T00:49:58-08:00"
},
{
"level": 2,
"level_name": "neighborhood",
"name": "The Mission, San Francisco, CA",
"normal_name": "The Mission",
"woeid": 23512048,
"place_id": "Y12JWsKbApmnSQpbQg",
"geometry": {
"type": "Polygon",
"coordinates": [],
"bbox": []
},
"label": null,
"best_guess": false,
"id": 59358801,
"located_at": "2008-12-18T00:49:58-08:00"
},
}
In this case the first object has a level of 0, so the index_offset is also 0.
Prerequisites
To query Fire Eagle we call in some existing libraries to handle the OAuth layer and the Fire Eagle API call. Your bookmarklet will need to add the following scripts into the page:
The SHA1 encryption algorithm
The OAuth wrapper
An extension for the OAuth wrapper
The Fire Eagle wrapper itself
When the bookmarklet is first run, we’ll insert these scripts into the document. We’re also inserting a stylesheet to dress up the UI that will be generated.
If you want to follow along any of the more mundane parts of the bookmarklet, you can download the full source code.
Rendering
This bookmarklet can be extended to support any formatting of your location you like, but for sake of example I’m going to build three common formatters that you’ll find useful for common location scenarios: Sites which already ask for your location; and in publishing systems that accept tags or HTML mark-up.
All the rendering functions are items in a renderers object, so they can be iterated through easily, making it trivial to add new formatting functions as your find new use cases (just add another function to the object).
var renderers = {
geotag: function(user) {
if(LocationDetail.EXACT !== index_offset) {
return false;
}
else {
var coords =
user.location_hierarchy[LocationDetail.EXACT].geometry.coordinates;
return "geo:lat=" + coords[0] + ", geo:lon=" + coords[1];
}
},
city: function(user) {
if(LocationDetail.CITY < index_offset) {
return false;
}
else {
return user.location_hierarchy[LocationDetail.CITY - index_offset].name;
}
}
You should always fail gracefully, and in line with catering to users who choose not to share their location precisely, always check that the location has been returned at the level you require. Geotags are expected to be precise, so if an exact location is unavailable, returning false will tell the rendering aspect of the bookmarklet to ignore the function altogether.
These first two are quite simple, geotag returns geo:lat=-0.2347530752, geo:lon=67.232323 and city returns San Francisco, CA.
This final renderer creates a chunk of HTML using the adr and geo microformats, using all available aspects of the location hierarchy, and can be used to geotag any content you write on your blog or in comments:
html: function(user) {
var geostring = '';
var adrstring = '';
var adr = [];
adr.push('<p class="adr">');
// city
if(LocationDetail.CITY >= index_offset) {
adr.push(
'\n <span class="locality">'
+ user.location_hierarchy[LocationDetail.CITY-index_offset].normal_name
+ '</span>,'
);
}
// county
if(LocationDetail.REGION >= index_offset) {
adr.push(
'\n <span class="region">'
+ user.location_hierarchy[LocationDetail.REGION-index_offset].normal_name
+ '</span>,'
);
}
// locality
if(LocationDetail.STATE >= index_offset) {
adr.push(
'\n <span class="region">'
+ user.location_hierarchy[LocationDetail.STATE-index_offset].normal_name
+ '</span>,'
);
}
// country
if(LocationDetail.COUNTRY >= index_offset) {
adr.push(
'\n <span class="country-name">'
+ user.location_hierarchy[LocationDetail.COUNTRY-index_offset].normal_name
+ '</span>'
);
}
// postal
if(LocationDetail.POSTAL >= index_offset) {
adr.push(
'\n <span class="postal-code">'
+ user.location_hierarchy[LocationDetail.POSTAL-index_offset].normal_name
+ '</span>,'
);
}
adr.push('\n</p>\n');
adrstring = adr.join('');
if(LocationDetail.EXACT === index_offset) {
var coords =
user.location_hierarchy[LocationDetail.EXACT].geometry.coordinates;
geostring = '<p class="geo">'
+'\n <span class="latitude">'
+ coords[0]
+ '</span>;'
+ '\n <span class="longitude">'
+ coords[1]
+ '</span>\n</p>\n';
}
return (adrstring + geostring);
}
Here we check the availability of every level of location and build it into the adr and geo patterns as appropriate. Just as for the geotag function, if there’s no exact location the geo markup won’t be returned.
Finally, there’s a rendering method which creates a container for all this data, renders all the applicable location formats and then displays them in the page for a user to copy and paste. You can throw this together with DOM methods and some simple styling, or roll in some components from YUI or JQuery to handle drawing full featured overlays.
You can see this simple implementation for rendering in the full source code.
Make the call
With a framework in place to render Fire Eagle’s location hierarchy, the only thing that remains is to actually request your location. Having already authed through Amadeus earlier, that’s as simple as instantiating the Fire Eagle JavaScript wrapper and making a single function call. It’s a big deal that whilst a lot of new technologies like OAuth add some complexity and require new knowledge to work with, APIs like Fire Eagle are really very simple indeed.
return {
run: function() {
insert_prerequisites();
setTimeout(
function() {
var fe = new FireEagle(
Keys.consumer_key,
Keys.consumer_secret,
Keys.user_token,
Keys.user_secret
);
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = fe.getUserUrl(
FireEagle.RESPONSE_FORMAT.json,
'Geomarklet.callback'
);
document.body.appendChild(script);
},
2000
);
},
callback: function(json) {
if(json.rsp && 'fail' == json.rsp.stat) {
alert('Error ' + json.rsp.code + ": " + json.rsp.message);
}
else {
index_offset = json.user.location_hierarchy[0].level;
draw_selector(json);
}
}
};
We first insert the prerequisite scripts required for the Fire Eagle request to function, and to prevent trying to instantiate the FireEagle object before it’s been loaded over the wire, the remaining instantiation and request is wrapped inside a setTimeout delay.
We then create the request URL, referencing the Geomarklet.callback callback function and then append the script to the document body — allowing a cross-domain request.
The callback itself is quite simple. Check for the presence and value of rsp.status to test for errors, and display them as required. If the request is successful set the index_offset — to adjust for the granularity of the location hierarchy — and then pass the object to the renderer.
The result? When Geomarklet.run() is called, your location from Fire Eagle is read, and each renderer displayed on the page in an easily copy and pasteable form, ready to be used however you need.
Deploy
The final step is to convert this code into a long string for use as a bookmarklet. Easiest for Mac users is the JavaScript bundle in TextMate — choose Bundles: JavaScript: Copy as Bookmarklet to Clipboard. Then create a new ‘Get Location’ bookmark in your browser of choice and paste in.
Those without TextMate can shrink their code down into a single line by first running their code through the JSLint tool (to ensure the code is free from errors and has all the required semi-colons) and then use a find-and-replace tool to remove line breaks from your code (or even run your code through JSMin to shrink it down).
With the bookmarklet created and added to your bookmarks bar, you can now call up your location on any page at all. Get a feel for a web where your location is just another reliable part of the browsing experience.
Where next?
So, the Geomarklet you’ve been guided through is a pretty simple premise and pretty simple output. But from this base you can start to extend: Add code that will insert each of the location renderings directly into form fields, perhaps, or how about site-specific handlers to add your location tags into the correct form field in Wordpress or Tumblr? Paste in your current location to Google Maps? Or Flickr?
Geomarklet gives you a base to start experimenting with location on your own pages and the sites you browse daily.
The introduction of consumer accessible geo to the web is an adventure of discovery; not so much discovering new locations, but discovering location itself. |
2008 |
Ben Ward |
benward |
2008-12-21T00:00:00+00:00 |
https://24ways.org/2008/geotag-everywhere-with-fire-eagle/ |
code |
| 163 |
Get To Grips with Slippy Maps |
Online mapping has definitely hit mainstream. Google Maps made ‘slippy maps’ popular and made it easy for any developer to quickly add a dynamic map to his or her website. You can now find maps for store locations, friends nearby, upcoming events, and embedded in blogs.
In this tutorial we’ll show you how to easily add a map to your site using the Mapstraction mapping library. There are many map providers available to choose from, each with slightly different functionality, design, and terms of service. Mapstraction makes deciding which provider to use easy by allowing you to write your mapping code once, and then easily switch providers.
Assemble the pieces
Utilizing any of the mapping library typically consists of similar overall steps:
Create an HTML div to hold the map
Include the Javascript libraries
Create the Javascript Map element
Set the initial map center and zoom level
Add markers, lines, overlays and more
Create the Map Div
The HTML div is where the map will actually show up on your page. It needs to have a unique id, because we’ll refer to that later to actually put the map here. This also lets you have multiple maps on a page, by creating individual divs and Javascript map elements. The size of the div also sets the height and width of the map. You set the size using CSS, either inline with the element, or via a CSS reference to the element id or class. For this example, we’ll use inline styling.
<div id="map" style="width: 400px; height: 400px;"></div>
Include Javascript libraries
A mapping library is like any Javascript library. You need to include the library in your page before you use the methods of that library. For our tutorial, we’ll need to include at least two libraries: Mapstraction, and the mapping API(s) we want to display. Our first example we’ll use the ubiquitous Google Maps library. However, you can just as easily include Yahoo, MapQuest, or any of the other supported libraries.
Another important aspect of the mapping libraries is that many of them require an API key. You will need to agree to the terms of service, and get an API key these.
<script src="http://maps.google.com/maps?file=api&v=2&key=YOUR_KEY" type="text/javascript"></script>
<script type="text/javascript" src="http://mapstraction.com/src/mapstraction.js"></script>
Create the Map
Great, we’ve now put in all the pieces we need to start actually creating our map. This is as simple as creating a new Mapstraction object with the id of the HTML div we created earlier, and the name of the mapping provider we want to use for this map.
With several of the mapping libraries you will need to set the map center and zoom level before the map will appear. The map centering actually triggers the initialization of the map.
var mapstraction = new Mapstraction('map','google');
var myPoint = new LatLonPoint(37.404,-122.008);
mapstraction.setCenterAndZoom(myPoint, 10);
A note about zoom levels. The setCenterAndZoom function takes two parameters, the center as a LatLonPoint, and a zoom level that has been defined by mapping libraries. The current usage is for zoom level 1 to be “zoomed out”, or view the entire earth – and increasing the zoom level as you zoom in. Typically 17 is the maximum zoom, which is about the size of a house.
Different mapping providers have different quality of zoomed in maps over different parts of the world. This is a perfect reason why using a library like Mapstraction is very useful, because you can quickly change mapping providers to accommodate users in areas that have bad coverage with some maps.
To switch providers, you just need to include the Javascript library, and then change the second parameter in the Mapstraction creation. Or, you can call the switch method to dynamically switch the provider.
So for Yahoo Maps (demo):
var mapstraction = new Mapstraction('map','yahoo');
or Microsoft Maps (demo):
var mapstraction = new Mapstraction('map','microsoft');
want a 3D globe in your browser? try FreeEarth (demo):
var mapstraction = new Mapstraction('map','freeearth');
or even OpenStreetMap (free your data!) (demo):
var mapstraction = new Mapstraction('map','openstreetmap');
Visit the Mapstraction multiple map demo page for an example of how easy it is to have many maps on your page, each with a different provider.
Adding Markers
While adding your first map is fun, and you can probably spend hours just sliding around, the point of adding a map to your site is usually to show the location of something. So now you want to add some markers. There are a couple of ways to add to your map.
The simplest is directly creating markers. You could either hard code this into a rather static page, or dynamically generate these using whatever tools your site is built on.
var marker = new Marker( new LatLonPoint(37.404,-122.008) );
marker.setInfoBubble("It's easy to add maps to your site");
mapstraction.addMarker( marker );
There is a lot more you can do with markers, including changing the icon, adding timestamps, automatically opening the bubble, or making them draggable.
While it is straight-forward to create markers one by one, there is a much easier way to create a large set of markers. And chances are, you can make it very easy by extending some data you already are sharing: RSS.
Specifically, using GeoRSS you can easily add a large set of markers directly to a map. GeoRSS is a community built standard (like Microformats) that added geographic markup to RSS and Atom entries. It’s as simple as adding <georss:point>42 -83</georss:point> to your feeds to share items via GeoRSS. Once you’ve done that, you can add that feed as an ‘overlay’ to your map using the function:
mapstraction.addOverlay("http://api.flickr.com/services/feeds/groups_pool.gne?id=322338@N20&format=rss_200&georss=1");
Mapstraction also supports KML for many of the mapping providers. So it’s easy to add various data sources together with your own data. Check out Mapufacture for a growing index of available GeoRSS feeds and KML documents.
Play with your new toys
Mapstraction offers a lot more functionality you can utilize for demonstrating a lot of geographic data on your website. It also includes geocoding and routing abstraction layers for making sure your users know where to go. You can see more on the Mapstraction website: http://mapstraction.com. |
2007 |
Andrew Turner |
andrewturner |
2007-12-02T00:00:00+00:00 |
https://24ways.org/2007/get-to-grips-with-slippy-maps/ |
code |
| 307 |
Get the Balance Right: Responsive Display Text |
Last year in 24 ways I urged you to Get Expressive with Your Typography. I made the case for grabbing your readers’ attention by setting text at display sizes, that is to say big. You should consider very large text in the same way you might a hero image: a picture that creates an atmosphere and anchors your layout.
When setting text to be read, it is best practice to choose body and subheading sizes from a pre-defined scale appropriate to the viewport dimensions. We set those sizes using rems, locking the text sizes together so they all scale according to the page default and your reader’s preferences. You can take the same approach with display text by choosing larger sizes from the same scale.
However, display text, as defined by its purpose and relative size, is text to be seen first, and read second. In other words a picture of text. When it comes to pictures, you are likely to scale all scene-setting imagery - cover photos, hero images, and so on - relative to the viewport. Take the same approach with display text: lock the size and shape of the text to the screen or browser window.
Introducing viewport units
With CSS3 came a new set of units which are locked to the viewport. You can use these viewport units wherever you might otherwise use any other unit of length such as pixels, ems or percentage. There are four viewport units, and in each case a value of 1 is equal to 1% of either the viewport width or height as reported in reference1 pixels:
vw - viewport width,
vh - viewport height,
vmin - viewport height or width, whichever is smaller
vmax - viewport height or width, whichever is larger
In one fell swoop you can set the size of a display heading to be proportional to the screen or browser width, rather than choosing from a scale in a series of media queries. The following makes the heading font size 13% of the viewport width:
h1 {
font-size: 13 vw;
}
So for a selection of widths, the rendered font size would be:
Rendered font size (px)
Viewport width
13 vw
320
42
768
100
1024
133
1280
166
1920
250
A problem with using vw in this manner is the difference in text block proportions between portrait and landscape devices. Because the font size is based on the viewport width, the text on a landscape display is far bigger than when rendered on the same device held in a portrait orientation.
Landscape text is much bigger than portrait text when using vw units.
The proportions of the display text relative to the screen are so dissimilar that each orientation has its own different character, losing the inconsistency and considered design you would want when designing to make an impression.
However if the text was the same size in both orientations, the visual effect would be much more consistent. This where vmin comes into its own. Set the font size using vmin and the size is now set as a proportion of the smallest side of the viewport, giving you a far more consistent rendering.
h1 {
font-size: 13vmin;
}
Landscape text is consistent with portrait text when using vmin units.
Comparing vw and vmin renderings for various common screen dimensions, you can see how using vmin keeps the text size down to a usable magnitude:
Rendered font size (px)
Viewport
13 vw
13 vmin
320 × 480
42
42
414 × 736
54
54
768 × 1024
100
100
1024 × 768
133
100
1280 × 720
166
94
1366 × 768
178
100
1440 × 900
187
117
1680 × 1050
218
137
1920 × 1080
250
140
2560 × 1440
333
187
Hybrid font sizing
Using vertical media queries to set text in direct proportion to screen dimensions works well when sizing display text. In can be less desirable when sizing supporting text such as sub-headings, which you may not want to scale upwards at the same rate as the display text. For example, we can size a subheading using vmin so that it starts at 16 px on smaller screens and scales up in the same way as the main heading:
h1 {
font-size: 13vmin;
}
h2 {
font-size: 5vmin;
}
Using vmin alone for supporting text can scale it too quickly
The balance of display text to supporting text on the phone works well, but the subheading text on the tablet, even though it has been increased in line with the main heading, is starting to feel disproportionately large and a little clumsy. This problem becomes magnified on even bigger screens.
A solution to this is use a hybrid method of sizing text2. We can use the CSS calc() function to calculate a font size simultaneously based on both rems and viewport units. For example:
h2 {
font-size: calc(0.5rem + 2.5vmin);
}
For a 320 px wide screen, the font size will be 16 px, calculated as follows:
(0.5 × 16) + (320 × 0.025) = 8 + 8 = 16px
For a 768 px wide screen, the font size will be 27 px:
(0.5 × 16) + (768 × 0.025) = 8 + 19 = 27px
This results in a more balanced subheading that doesn’t take emphasis away from the main heading:
To give you an idea of the effect of using a hybrid approach, here’s a side-by-side comparison of hybrid and viewport text sizing:
table.ex--scale{width:100%;overflow: hidden;} table.ex--scale td{vertical-align:baseline;text-align:center;padding:0} tr.ex--scale-key{color:#666} tr.ex--scale-key td{font-size:.875rem;padding:0 0.125em} .ex--scale-2 tr.ex--scale-size{color:#ccc} tr.ex--scale-size td{font-size:1em;line-height:.34em;padding-bottom:.5rem} td.ex--scale-step{color:#000} td.ex--scale-hilite{color:red} .ex--scale-3 tr.ex--scale-size td{line-height:.9em}
top: calc() hybrid method; bottom: vmin only
16
20
27
32
35
40
44
16
24
38
48
54
64
72
320
480
768
960
1080
1280
1440
Over this festive period, try experiment with the proportion of rem and vmin in your hybrid calculation to see what feels best for your particular setting.
A reference pixel is based on the logical resolution of a device which takes into account double density screens such as Retina displays. ↩︎
For even more sophisticated uses of hybrid text sizing see the work of Mike Riethmuller. ↩︎ |
2016 |
Richard Rutter |
richardrutter |
2016-12-09T00:00:00+00:00 |
https://24ways.org/2016/responsive-display-text/ |
code |
| 206 |
Getting Hardboiled with CSS Custom Properties |
Custom Properties are a fabulous new feature of CSS and have widespread support in contemporary browsers. But how do we handle browsers without support for CSS Custom Properties? Do we wait until those browsers are lying dead in a ditch before we use them? Do we tool up and prop up our CSS using a post-processor? Or do we get tough? Do we get hardboiled?
Previously only pre-processing tools like LESS and Sass enabled developers to use variables in their stylesheets, but now Custom Properties have brought variables natively to CSS.
How do you write a custom property? It’s hardly a mystery. Simply add two dashes to the start of a style rule. Like this:
--color-text-default : black;
If you’re more the underscore type, try this:
--color_text_default : black;
Hyphens or underscores are allowed in property names, but don’t be a chump and try to use spaces.
Custom property names are also case-sensitive, so --color-text-default and --Color_Text_Default are two distinct properties.
To use a custom property in your style rules, var() tells a browser to retrieve the value of a property. In the next example, the browser retrieves the black colour from the color-text-default variable and applies it to the body element:
body {
color : var(--color-text-default);
}
Like variables in LESS or Sass, CSS Custom Properties mean you don’t have to be a dumb mug and repeat colour, font, or size values multiple times in your stylesheets. Unlike a preprocessor variable though, CSS Custom Properties use the cascade, can be modified by media queries and other state changes, and can also be manipulated by Javascript.
(Serg Hospodarets wrote a fabulous primer on CSS Custom Properties where he dives deeper into the code and possible applications.)
Browser support
Now it’s about this time that people normally mention browser support. So what about support for CSS Custom Properties? Current versions of Chrome, Edge, Firefox, Opera, and Safari are all good. Internet Explorer 11 and before? Opera Mini? Nasty.
Sound familiar?
Can I Use css-variables? Data on support for the css-variables feature across the major browsers from caniuse.com.
Not to worry, we can manually check for Custom Property support in a browser by using an @support directive, like this:
--color-text-default : black;
body {
color : black;
}
@supports ((--foo : bar)) {
body {
color : var(--color-text-default);
}
}
In that example we first set body element text to black and then override that colour with a Custom Property value when the browser supports our fictitious foo bar variable.
Substitutions
If we reference a variable that hasn’t been defined, that won’t be a problem as browsers are smart enough to ignore the value altogether. If we need a cast iron alibi, use substitutions to specify a fall-back value.
body {
color : var(--color-text-default, black);
}
Substitutions are similar to font stacks in that they contain a comma separated list of values. If there’s no value associated with a property, a browser will ignore it and move onto the next value in the list.
Post-processing
Of course we could use a post-processor plugin to turn Custom Properties into plain CSS, but hang on one goddam minute kiddo.
Haven’t we been down this road before? Didn’t we engineer elaborate workarounds to enable us to use ‘advanced’ CSS3 properties like border-radius, CSS columns, and Flexbox in the past? We did what we had to do to get the job done, but came away feeling dirty.
I think there’s a better way, one that allows us to enjoy the benefits of CSS Custom Properties in browsers that support them, while providing an appropriate, but not identical experience, for people who use less capable browsers. Guess what, I’ve been down this road before too.
2Tone Stuff & Nonsense
When Internet Explorer 6 was the big dumb browser everyone hated, I served two different designs on my website.
For the modern browsers of the time, mod arrows and targets were everywhere in glorious red, white, and blue, and I implemented all of them using CSS attribute selectors which were considered advanced at the time:
[class="banner"] {
background-colour : red;
}
Internet Explorer 6 ignored any selectors it didn’t understand, so people using that browser saw a simpler black and white, 2Tone-based design that I’d implemented for them using class selectors:
.banner {
background-colour : black;
}
[class="banner"] {
background-colour : red;
}
You don’t have to be a detective to find out that most people thought I’d lost my wits, but Microsoft even used my website as a reference when they tested attribute selectors in Internet Explorer 7. They did, as I suggested, “Stomp to da betta browser.”
Dumb browsers look the other way
So how does this approach relate to tackling any lack of support for CSS Custom Properties? How can we take advantage of them without worrying about browsers with no support and having to implement complex workarounds, or spending hours specifying fallbacks that perfectly match our designs?
Turns out, the answer is built into CSS, and always has been, because when browsers don’t know what they’re looking at, they look away.
All we have to do is first specify values for a simpler design first, and then follow that up with the values in our CSS Custom Properties:
body {
color : black;
color : var(--color-text-default, black);
}
All browsers understand the first value (black,) and if they‘re smart enough to understand the second (var(--color-text-default)), they’ll use it and override the first. If they’re too damn stupid to understand the custom property value, they’ll ignore it. Nobody dies.
Repeat this for every style that contains a variable, baking an alternative, perhaps simpler design into your stylesheets for people who use less capable browsers, just like I did with Stuff & Nonsense.
Conclusion
I doubt that anyone agrees with presenting a design that looks broken or unloved—and I’m not advocating for that—but websites need not look the same in every browser. We can use substitutions to present a simpler design to people using less capable browsers.
The decision when to start using new CSS properties isn‘t always a technical one. Sometimes a change in attitude about browser support is all that’s required. So get tough with dumb browsers and benefit from all the advantages that CSS Custom Properties offer. Get hardboiled.
Resources:
It’s Time To Start Using CSS Custom Properties—Smashing Magazine
Using CSS variables correctly—Mike Riethmuller
Developing Inspired Guides with CSS Custom Properties (variables)—Andy Clarke |
2017 |
Andy Clarke |
andyclarke |
2017-12-13T00:00:00+00:00 |
https://24ways.org/2017/getting-hardboiled-with-css-custom-properties/ |
code |
| 52 |
Git Rebasing: An Elfin Workshop Workflow |
This year Santa’s helpers have been tasked with making a garland. It’s a pretty simple task: string beads onto yarn in a specific order. When the garland reaches a specific length, add it to the main workshop garland. Each elf has a specific sequence they’re supposed to chain, which is given to them via a work order. (This is starting to sound like one of those horrible calculus problems. I promise it isn’t. It’s worse; it’s about Git.)
For the most part, the system works really well. The elves are able to quickly build up a shared chain because each elf specialises on their own bit of garland, and then links the garland together. Because of this they’re able to work independently, but towards the common goal of making a beautiful garland.
At first the elves are really careful with each bead they put onto the garland. They check with one another before merging their work, and review each new link carefully. As time crunches on, the elves pour a little more cheer into the eggnog cooler, and the quality of work starts to degrade. Tensions rise as mistakes are made and unkind words are said. The elves quickly realise they’re going to need a system to change the beads out when mistakes are made in the chain.
The first common mistake is not looking to see what the latest chain is that’s been added to the main garland. The garland is huge, and it sits on a roll in one of the corners of the workshop. It’s a big workshop, so it is incredibly impractical to walk all the way to the roll to check what the last link is on the chain. The elves, being magical, have set up a monitoring system that allows them to keep a local copy of the main garland at their workstation. It’s an imperfect system though, so the elves have to request a manual refresh to see the latest copy. They can request a new copy by running the command
git pull --rebase=preserve
(They found that if they ran git pull on its own, they ended up with weird loops of extra beads off the main garland, so they’ve opted to use this method.) This keeps the shared garland up to date, which makes things a lot easier. A visualisation of the rebase process is available.
The next thing the elves noticed is that if they worked on the main workshop garland, they were always running into problems when they tried to share their work back with the rest of the workshop. It was fine if they were working late at night by themselves, but in the middle of the day, it was horrible. (I’ve been asked not to talk about that time the fight broke out.) Instead of trying to share everything on their local copy of the main garland, the elves have realised it’s a lot easier to work on a new string and then knot this onto the main garland when their pattern repeat is finished. They generate a new string by issuing the following commands:
git checkout master
git checkout -b 1234_pattern-name
1234 represents the work order number and pattern-name describes the pattern they’re adding. Each bead is then added to the new link (git add bead.txt) and locked into place (git commit). Each elf repeats this process until the sequence of beads described in the work order has been added to their mini garland.
To combine their work with the main garland, the elves need to make a few decisions. If they’re making a single strand, they issue the following commands:
git checkout master
git merge --ff-only 1234_pattern-name
To share their work they publish the new version of the main garland to the workshop spool with the command git push origin master.
Sometimes this fails. Sharing work fails because the workshop spool has gotten new links added since the elf last updated their copy of the main workshop spool. This makes the elves both happy and sad. It makes them happy because it means the other elves have been working too, but it makes them sad because they now need to do a bit of extra work to close their work order.
To update the local copy of the workshop spool, the elf first unlinks the chain they just linked by running the command:
git reset --merge ORIG_HEAD
This works because the garland magic notices when the elves are doing a particularly dangerous thing and places a temporary, invisible bookmark to the last safe bead in the chain before the dangerous thing happened. The garland no longer has the elf’s work, and can be updated safely. The elf runs the command git pull --rebase=preserve and the changes all the other elves have made are applied locally.
With these new beads in place, the elf now has to restring their own chain so that it starts at the right place. To do this, the elf turns back to their own chain (git checkout 1234_pattern-name) and runs the command git rebase master. Assuming their bead pattern is completely unique, the process will run and the elf’s beads will be restrung on the tip of the main workshop garland.
Sometimes the magic fails and the elf has to deal with merge conflicts. These are kind of annoying, so the elf uses a special inspector tool to figure things out. The elf opens the inspector by running the command git mergetool to work through places where their beads have been added at the same points as another elf’s beads. Once all the conflicts are resolved, the elf saves their work, and quits the inspector. They might need to do this a few times if there are a lot of new beads, so the elf has learned to follow this update process regularly instead of just waiting until they’re ready to close out their work order.
Once their link is up to date, the elf can now reapply their chain as before, publish their work to the main workshop garland, and close their work order:
git checkout master
git merge --ff-only 1234_pattern-name
git push origin master
Generally this process works well for the elves. Sometimes, though, when they’re tired or bored or a little drunk on festive cheer, they realise there’s a mistake in their chain of beads. Fortunately they can fix the beads without anyone else knowing. These tools can be applied to the whole workshop chain as well, but it causes problems because the magic assumes that elves are only ever adding to the main chain, not removing or reordering beads on the fly. Depending on where the mistake is, the elf has a few different options.
Let’s pretend the elf has a sequence of five beads she’s been working on. The work order says the pattern should be red-blue-red-blue-red.
If the sequence of beads is wrong (for example, blue-blue-red-red-red), the elf can remove the beads from the chain, but keep the beads in her workstation using the command git reset --soft HEAD~5.
If she’s been using the wrong colours and the wrong pattern (for example, green-green-yellow-yellow-green), she can remove the beads from her chain and discard them from her workstation using the command git reset --hard HEAD~5.
If one of the beads is missing (for example, red-blue-blue-red), she can restring the beads using the first method, or she can use a bit of magic to add the missing bead into the sequence.
Using a tool that’s a bit like orthoscopic surgery, she first selects a sequence of beads which contains the problem. A visualisation of this process is available.
Start the garland surgery process with the command:
git rebase --interactive HEAD~4
A new screen comes up with the following information (the oldest bead is on top):
pick c2e4877 Red bead
pick 9b5555e Blue bead
pick 7afd66b Blue bead
pick e1f2537 Red bead
The elf adjusts the list, changing “pick” to “edit” next to the first blue bead:
pick c2e4877 Red bead
edit 9b5555e Blue bead
pick 7afd66b Blue bead
pick e1f2537 Red bead
She then saves her work and quits the editor. The garland magic has placed her back in time at the moment just after she added the first blue bead.
She needs to manually fix up her garland to add the new red bead. If the beads were files, she might run commands like vim beads.txt and edit the file to make the necessary changes.
Once she’s finished her changes, she needs to add her new bead to the garland (git add --all) and lock it into place (git commit). This time she assigns the commit message “Red bead – added” so she can easily find it.
The garland magic has replaced the bead, but she still needs to verify the remaining beads on the garland. This is a mostly automatic process which is started by running the command git rebase --continue.
The new red bead has been assigned a position formerly held by the blue bead, and so the elf must deal with a merge conflict. She opens up a new program to help resolve the conflict by running git mergetool.
She knows she wants both of these beads in place, so the elf edits the file to include both the red and blue beads.
With the conflict resolved, the elf saves her changes and quits the mergetool.
Back at the command line, the elf checks the status of her work using the command git status.
rebase in progress; onto 4a9cb9d
You are currently rebasing branch '2_RBRBR' on '4a9cb9d'.
(all conflicts fixed: run "git rebase --continue")
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: beads.txt
Untracked files:
(use "git add <file>..." to include in what will be committed)
beads.txt.orig
She removes the file added by the mergetool with the command rm beads.txt.orig and commits the edits she just made to the bead file using the commands:
git add beads.txt
git commit --message "Blue bead -- resolved conflict"
With the conflict resolved, the elf is able to continue with the rebasing process using the command git rebase --continue. There is one final conflict the elf needs to resolve. Once again, she opens up the visualisation tool and takes a look at the two conflicting files.
She incorporates the changes from the left and right column to ensure her bead sequence is correct.
Once the merge conflict is resolved, the elf saves the file and quits the mergetool. Once again, she cleans out the backup file added by the mergetool (rm beads.txt.orig) and commits her changes to the garland:
git add beads.txt
git commit --message "Red bead -- resolved conflict"
and then runs the final verification steps in the rebase process (git rebase --continue).
The verification process runs through to the end, and the elf checks her work using the command git log --oneline.
9269914 Red bead -- resolved conflict
4916353 Blue bead -- resolved conflict
aef0d5c Red bead -- added
9b5555e Blue bead
c2e4877 Red bead
She knows she needs to read the sequence from bottom to top (the oldest bead is on the bottom). Reviewing the list she sees that the sequence is now correct.
Sometimes, late at night, the elf makes new copies of the workshop garland so she can play around with the bead sequencer just to see what happens. It’s made her more confident at restringing beads when she’s found real mistakes. And she doesn’t mind helping her fellow elves when they run into trouble with their beads. The sugar cookies they leave her as thanks don’t hurt either. If you would also like to play with the bead sequencer, you can get a copy of the branches the elf worked.
Our lessons from the workshop:
By using rebase to update your branches, you avoid merge commits and keep a clean commit history.
If you make a mistake on one of your local branches, you can use reset to take commits off your branch. If you want to save the work, but uncommit it, add the parameter --soft. If you want to completely discard the work, use the parameter, --hard.
If you have merged working branch changes to the local copy of your master branch and it is preventing you from pushing your work to a remote repository, remove these changes using the command reset with the parameter --merge ORIG_HEAD before updating your local copy of the remote master branch.
If you want to make a change to work that was committed a little while ago, you can use the command rebase with the parameter --interactive. You will need to include how many commits back in time you want to review. |
2015 |
Emma Jane Westby |
emmajanewestby |
2015-12-07T00:00:00+00:00 |
https://24ways.org/2015/git-rebasing/ |
code |
| 15 |
Git for Grown-ups |
You are a clever and talented person. You create beautiful designs, or perhaps you have architected a system that even my cat could use. Your peers adore you. Your clients love you. But, until now, you haven’t *&^#^! been able to make Git work. It makes you angry inside that you have to ask your co-worker, again, for that *&^#^! command to upload your work.
It’s not you. It’s Git. Promise.
Yes, this is an article about the popular version control system, Git. But unlike just about every other article written about Git, I’m not going to give you the top five commands that you need to memorize; and I’m not going to tell you all your problems would be solved if only you were using this GUI wrapper or that particular workflow. You see, I’ve come to a grand realization: when we teach Git, we’re doing it wrong.
Let me back up for a second and tell you a little bit about the field of adult education. (Bear with me, it gets good and will leave you feeling both empowered and righteous.) Andragogy, unlike pedagogy, is a learner-driven educational experience. There are six main tenets to adult education:
Adults prefer to know why they are learning something.
The foundation of the learning activities should include experience.
Adults prefer to be able to plan and evaluate their own instruction.
Adults are more interested in learning things which directly impact their daily activities.
Adults prefer learning to be oriented not towards content, but towards problems.
Adults relate more to their own motivators than to external ones.
Nowhere in this list does it include “memorize the five most popular Git commands”. And yet this is how we teach version control: init, add, commit, branch, push. You’re an expert! Sound familiar? In the hierarchy of learning, memorizing commands is the lowest, or most basic, form of learning. At the peak of learning you are able to not just analyze and evaluate a problem space, but create your own understanding in relation to your existing body of knowledge.
“Fine,” I can hear you saying to yourself. “But I’m here to learn about version control.” Right you are! So how can we use this knowledge to master Git? First of all: I give you permission to use Git as a tool. A tool which you control and which you assign tasks to. A tool like a hammer, or a saw. Yes, your mastery of your tools will shape the kinds of interactions you have with your work, and your peers. But it’s yours to control. Git was written by kernel developers for kernel development. The web world has adopted Git, but it is not a tool designed for us and by us. It’s no Sass, y’know? Git wasn’t developed out of our frustration with managing CSS files in an increasingly complex ecosystem of components and atomic design. So, as you work through the next part of this article, give yourself a bit of a break. We’re in this together, and it’s going to be OK.
We’re going to do a little activity. We’re going to create your perfect Git cheatsheet.
I want you to start by writing down a list of all the people on your code team. This list may include:
developers
designers
project managers
clients
Next, I want you to write down a list of all the ways you interact with your team. Maybe you’re a solo developer and you do all the tasks. Maybe you only do a few things. But I want you to write down a list of all the tasks you’re actually responsible for. For example, my list looks like this:
writing code
reviewing code
publishing tested code to your server(s)
troubleshooting broken code
The next list will end up being a series of boxes in a diagram. But to start, I want you to write down a list of your tools and constraints. This list potentially has a lot of noun-like items and verb-like items:
code hosting system (Bitbucket? GitHub? Unfuddle? self-hosted?)
server ecosystem (dev/staging/live)
automated testing systems or review gates
automated build systems (that Jenkins dude people keep referring to)
Brilliant! Now you’ve got your actors and your actions, it’s time to shuffle them into a diagram. There are many popular workflow patterns. None are inherently right or wrong; rather, some are more or less appropriate for what you are trying to accomplish.
Centralized workflow
Everyone saves to a single place. This workflow may mean no version control, or a very rudimentary version control system which only ever has a single copy of the work available to the team at any point in time.
Branching workflow
Everyone works from a copy of the same place, merging their changes into the main copy as their work is completed. Think of the branches as a motorcycle sidecar: they’re along for the ride and probably cannot exist in isolation of the main project for long without serious danger coming to the either the driver or sidecar passenger. Branches are a fundamental concept in version control — they allow you to work on new features, bug fixes, and experimental changes within a single repository, but without forcing the changes onto others working from the same branch.
Forking workflow
Everyone works from their own, independent repository. A fork is an exact duplicate of a repository that a developer can make their own changes to. It can be kept up to date with additional changes made in other repositories, but it cannot force its changes onto another’s repository. A fork is a complete repository which can use its own workflow strategies. If developers wish to merge their work with the main project, they must make a request of some kind (submit a patch, or a pull request) which the project collaborators may choose to adopt or reject. This workflow is popular for open source projects as it enforces a review process.
Gitflow workflow
A specific workflow convention which includes five streams of parallel coding efforts: master, development, feature branches, release branches, and hot fixes. This workflow is often simplified down to a few elements by web teams, but may be used wholesale by software product teams. The original article describing this workflow was written by Vincent Driessen back in January 2010.
But these workflows aren’t about you yet, are they? So let’s make the connections.
From the list of people on your team you identified earlier, draw a little circle. Give each of these circles some eyes and a smile. Now I want you to draw arrows between each of these people in the direction that code (ideally) flows. Does your designer create responsive prototypes which are pushed to the developer? Draw an arrow to represent this.
Chances are high that you don’t just have people on your team, but you also have some kind of infrastructure. Hopefully you wrote about it earlier. For each of the servers and code repositories in your infrastructure, draw a square. Now, add to your diagram the relationships between the people and each of the machines in the infrastructure. Who can deploy code to the live server? How does it really get there? I bet it goes through some kind of code hosting system, such as GitHub. Draw in those arrows.
But wait!
The code that’s on your development machine isn’t the same as the live code. This is where we introduce the concept of a branch in version control. In Git, a repository contains all of the code (sort of). A branch is a fragment of the code that has been worked on in isolation to the other branches within a repository. Often branches will have elements in common. When we compare two (or more) branches, we are asking about the difference (or diff) between these two slivers. Often the master branch is used on production, and the development branch is used on our dev server. The difference between these two branches is the untested code that is not yet deployed.
On your diagram, see if you can colour-code according to the branch names at each of the locations within your infrastructure. You might find it useful to make a few different copies of the diagram to isolate each of the tasks you need to perform. For example: our team has a peer review process that each branch must go through before it is merged into the shared development branch.
Finally, we are ready to add the Git commands necessary to make sense of the arrows in our diagram. If we are bringing code to our own workstation we will issue one of the following commands: clone (the first time we bring code to our workstation) or pull. Remembering that a repository contains all branches, we will issue the command checkout to switch from one branch to another within our own workstation. If we want to share a particular branch with one of our team mates, we will push this branch back to the place we retrieved it from (the origin). Along each of the arrows in your diagram, write the name of the command you are are going to use when you perform that particular task.
From here, it’s up to you to be selfish. Before asking Git what command it would like you to use, sketch the diagram of what you want. Git is your tool, you are not Git’s tool. Draw the diagram. Communicate your tasks with your team as explicitly as you can. Insist on being a selfish adult learner — demand that others explain to you, in ways that are relevant to you, how to do the things you need to do today. |
2013 |
Emma Jane Westby |
emmajanewestby |
2013-12-04T00:00:00+00:00 |
https://24ways.org/2013/git-for-grownups/ |
code |
| 76 |
Giving CSS Animations and Transitions Their Place |
CSS animations and transitions may not sit squarely in the realm of the behaviour layer, but they’re stepping up into this area that used to be pure JavaScript territory. Heck, CSS might even perform better than its JavaScript equivalents in some cases. That’s pretty serious! With CSS’s new tricks blurring the lines between presentation and behaviour, it can start to feel bloated and messy in our CSS files. It’s an uncomfortable feeling.
Here are a pair of methods I’ve found to be pretty helpful in keeping the potential bloat and wire-crossing under control when CSS has its hands in both presentation and behaviour.
Same eggs, more baskets
Structuring your CSS to have separate files for layout, typography, grids, and so on is a fairly common approach these days. But which one do you put your transitions and animations in? The initial answer, as always, is “it depends”.
Small effects here and there will likely sit just fine with your other styles. When you move into more involved effects that require multiple animations and some logic support from JavaScript, it’s probably time to choose none of the above, and create a separate CSS file just for them.
Putting all your animations in one file is a huge help for code organization. Even if you opt for a name less literal than animations.css, you’ll know exactly where to go for anything CSS animation related. That saves time and effort when it comes to editing and maintenance. Keeping track of which animations are still currently used is easier when they’re all grouped together as well. And as an added bonus, you won’t have to look at all those horribly unattractive and repetitive prefixed @-keyframe rules unless you actually need to.
An animations.css file might look something like the snippet below. It defines each animation’s keyframes and defines a class for each variation of that animation you’ll be using. Depending on the situation, you may also want to include transitions here in a similar way. (I’ve found defining transitions as their own class, or mixin, to be a huge help in past projects for me.)
// defining the animation
@keyframes catFall {
from { background-position: center 0;}
to {background-position: center 1000px;}
}
@-webkit-keyframes catFall {
from { background-position: center 0;}
to {background-position: center 1000px;}
}
@-moz-keyframes catFall {
from { background-position: center 0;}
to {background-position: center 1000px;}
}
@-ms-keyframes catFall {
from { background-position: center 0;}
to {background-position: center 1000px;}
}
…
// class that assigns the animation
.catsBackground {
height: 100%;
background: transparent url(../endlessKittens.png) 0 0 repeat-y;
animation: catFall 1s linear infinite;
-webkit-animation: catFall 1s linear infinite;
-moz-animation: catFall 1s linear infinite;
-ms-animation: catFall 1s linear infinite;
}
If we don’t need it, why load it?
Having all those CSS animations and transitions in one file gives us the added flexibility to load them only when we want to. Loading a whole lot of things that will never be used might seem like a bit of a waste.
While CSS has us impressed with its motion chops, it falls flat when it comes to the logic and fine-grained control. JavaScript, on the other hand, is pretty good at both those things. Chances are the content of your animations.css file isn’t acting alone. You’ll likely be adding and removing classes via JavaScript to manage your CSS animations at the very least. If your CSS animations are so entwined with JavaScript, why not let them hang out with the rest of the behaviour layer and only come out to play when JavaScript is supported?
Dynamically linking your animations.css file like this means it will be completely ignored if JavaScript is off or not supported. No JavaScript? No additional behaviour, not even the parts handled by CSS.
<script>
document.write('<link rel="stylesheet" type="text/css" href="animations.css">');
</script>
This technique comes up in progressive enhancement techniques as well, but it can help here to keep your presentation and behaviour nicely separated when more than one language is involved. The aim in both cases is to avoid loading files we won’t be using.
If you happen to be doing something a bit fancier – like 3-D transforms or critical animations that require more nuanced fallbacks – you might need something like modernizr to step in to determine support more specifically. But the general idea is the same.
Summing it all up
Using a couple of simple techniques like these, we get to pick where to best draw the line between behaviour and presentation based on the situation at hand, not just on what language we’re using. The power of when to separate and how to reassemble the individual pieces can be even greater if you use preprocessors as part of your process. We’ve got a lot of options! The important part is to make forward-thinking choices to save your future self, and even your current self, unnecessary headaches. |
2012 |
Val Head |
valhead |
2012-12-08T00:00:00+00:00 |
https://24ways.org/2012/giving-css-animations-and-transitions-their-place/ |
code |
| 95 |
Giving Content Priority with CSS3 Grid Layout |
Browser support for many of the modules that are part of CSS3 have enabled us to use CSS for many of the things we used to have to use images for. The rise of mobile browsers and the concept of responsive web design has given us a whole new way of looking at design for the web. However, when it comes to layout, we haven’t moved very far at all. We have talked for years about separating our content and source order from the presentation of that content, yet most of us have had to make decisions on source order in order to get a certain visual layout.
Owing to some interesting specifications making their way through the W3C process at the moment, though, there is hope of change on the horizon. In this article I’m going to look at one CSS module, the CSS3 grid layout module, that enables us to define a grid and place elements on to it. This article comprises a practical demonstration of the basics of grid layout, and also a discussion of one way in which we can start thinking of content in a more adaptive way.
Before we get started, it is important to note that, at the time of writing, these examples work only in Internet Explorer 10. CSS3 grid layout is a module created by Microsoft, and implemented using the -ms prefix in IE10. My examples will all use the -ms prefix, and not include other prefixes simply because this is such an early stage specification, and by the time there are implementations in other browsers there may be inconsistencies. The implementation I describe today may well change, but is also there for your feedback.
If you don’t have access to IE10, then one way to view and test these examples is by signing up for an account with Browserstack – the free trial would give you time to have a look. I have also included screenshots of all relevant stages in creating the examples.
What is CSS3 grid layout?
CSS3 grid layout aims to let developers divide up a design into a grid and place content on to that grid. Rather than trying to fabricate a grid from floats, you can declare an actual grid on a container element and then use that to position the elements inside. Most importantly, the source order of those elements does not matter.
Declaring a grid
We declare a grid using a new value for the display property: display: grid. As we are using the IE10 implementation here, we need to prefix that value: display: -ms-grid;.
Once we have declared our grid, we set up the columns and rows using the grid-columns and grid-rows properties.
.wrapper {
display: -ms-grid;
-ms-grid-columns: 200px 20px auto 20px 200px;
-ms-grid-rows: auto 1fr;
}
In the above example, I have declared a grid on the .wrapper element. I have used the grid-columns property to create a grid with a 200 pixel-wide column, a 20 pixel gutter, a flexible width auto column that will stretch to fill the available space, another 20 pixel-wide gutter and a final 200 pixel sidebar: a flexible width layout with two fixed width sidebars. Using the grid-rows property I have created two rows: the first is set to auto so it will stretch to fill whatever I put into it; the second row is set to 1fr, a new value used in grids that means one fraction unit. In this case, one fraction unit of the available space, effectively whatever space is left.
Positioning items on the grid
Now I have a simple grid, I can pop items on to it. If I have a <div> with a class of .main that I want to place into the second row, and the flexible column set to auto I would use the following CSS:
.content {
-ms-grid-column: 3;
-ms-grid-row: 2;
-ms-grid-row-span: 1;
}
If you are old-school, you may already have realised that we are essentially creating an HTML table-like layout structure using CSS. I found the concept of a table the most helpful way to think about the grid layout module when trying to work out how to place elements.
Creating grid systems
As soon as I started to play with CSS3 grid layout, I wanted to see if I could use it to replicate a flexible grid system like this fluid 16-column 960 grid system.
I started out by defining a grid on my wrapper element, using fractions to make this grid fluid.
.wrapper {
width: 90%;
margin: 0 auto 0 auto;
display: -ms-grid;
-ms-grid-columns: 1fr (4.25fr 1fr)[16];
-ms-grid-rows: (auto 20px)[24];
}
Like the 960 grid system I was using as an example, my grid starts with a gutter, followed by the first actual column, plus another gutter repeated sixteen times. What this means is that if I want to span two columns, as far as the grid layout module is concerned that is actually three columns: two wide columns, plus one gutter. So this needs to be accounted for when positioning items.
I created a CSS class for each positioning option: column position; rows position; and column span. For example:
.grid1 {-ms-grid-column: 2;} /* applying this class positions an item in the first column (the gutter is column 1) */
.grid2 {-ms-grid-column: 4;} /* 2nd column - gutter|column 1|gutter */
.grid3 {-ms-grid-column: 6;} /* 3rd column - gutter|column 1|gutter|column2|gutter */
.row1 {-ms-grid-row:1;}
.row2 {-ms-grid-row:3;}
.row3 {-ms-grid-row:5;}
.colspan1 {-ms-grid-column-span:1;}
.colspan2 {-ms-grid-column-span:3;}
.colspan3 {-ms-grid-column-span:5;}
I could then add multiple classes to each element to set the position on on the grid.
This then gives me a replica of the fluid grid using CSS3 grid layout. To see this working fire up IE10 and view Example 1.
This works, but…
This worked, but isn’t ideal. I considered not showing this stage of my experiment – however, I think it clearly shows how the grid layout module works and is a useful starting point. That said, it’s not an approach I would take in production. First, we have to add classes to our markup that tie an element to a position on the grid. This might not be too much of a problem if we are always going to maintain the sixteen-column grid, though, as I will show you that the real power of the grid layout module appears once you start to redefine the grid, using different grids based on media queries. If you drop to a six-column layout for small screens, positioning items into column 16 makes no sense any more.
Calculating grid position using LESS
As we’ve seen, if you want to use a grid with main columns and gutters, you have to take into account the spacing between columns as well as the actual columns. This means we have to do some calculating every time we place an item on the grid. In my example above I got around this by creating a CSS class for each position, allowing me to think in sixteen rather than thirty-two columns. But by using a CSS preprocessor, I can avoid using all the classes yet still think in main columns.
I’m using LESS for my example. My simple grid framework consists of one simple mixin.
.position(@column,@row,@colspan,@rowspan) {
-ms-grid-column: @column*2;
-ms-grid-row: @row*2-1;
-ms-grid-column-span: @colspan*2-1;
-ms-grid-row-span: @rowspan*2-1;
}
My mixin takes four parameters: column; row; colspan; and rowspan. So if I wanted to place an item on column four, row three, spanning two columns and one row, I would write the following CSS:
.box {
.position(4,3,2,1);
}
The mixin would return:
.box {
-ms-grid-column: 8;
-ms-grid-row: 5;
-ms-grid-column-span: 3;
-ms-grid-row-span: 1;
}
This saves me some typing and some maths. I could also add other prefixed values into my mixin as other browsers started to add support.
We can see this in action creating a new grid. Instead of adding multiple classes to each element, I can add one class; that class uses the mixin to create the position. I have also played around with row spans using my mixin and you can see we end up with a quite complicated arrangement of boxes. Have a look at example two in IE10. I’ve used the JavaScript LESS parser so that you can view the actual LESS that I use. Note that I have needed to escape the -ms prefixed properties with ~"" to get LESS to accept them.
This is looking better. I don’t have direct positioning information on each element in the markup, just a class name – I’ve used grid(x), but it could be something far more semantic. We can now take the example a step further and redefine the grid based on screen width.
Media queries and the grid
This example uses exactly the same markup as the previous example. However, we are now using media queries to detect screen width and redefine the grid using a different number of columns depending on that width.
I start out with a six-column grid, defining that on .wrapper, then setting where the different items sit on this grid:
.wrapper {
width: 90%;
margin: 0 auto 0 auto;
display: ~"-ms-grid"; /* escaped for the LESS parser */
-ms-grid-columns: ~"1fr (4.25fr 1fr)[6]"; /* escaped for the LESS parser */
-ms-grid-rows: ~"(auto 20px)[40]"; /* escaped for the LESS parser */
}
.grid1 { .position(1,1,1,1); }
.grid2 { .position(2,1,1,1); }
/* ... see example for all declarations ... */
Using media queries, I redefine the grid to nine columns when we hit a minimum width of 700 pixels.
@media only screen and (min-width: 700px) {
.wrapper {
-ms-grid-columns: ~"1fr (4.25fr 1fr)[9]";
-ms-grid-rows: ~"(auto 20px)[50]";
}
.grid1 { .position(1,1,1,1); }
.grid2 { .position(2,1,1,1); }
/* ... */
}
Finally, we redefine the grid for 960 pixels, back to the sixteen-column grid we started out with.
@media only screen and (min-width: 940px) {
.wrapper {
-ms-grid-columns:~" 1fr (4.25fr 1fr)[16]";
-ms-grid-rows:~" (auto 20px)[24]";
}
.grid1 { .position(1,1,1,1); }
.grid2 { .position(2,1,1,1); }
/* ... */
}
If you view example three in Internet Explorer 10 you can see how the items reflow to fit the window size. You can also see, looking at the final set of blocks, that source order doesn’t matter. You can pick up a block from anywhere and place it in any position on the grid.
Laying out a simple website
So far, like a toddler on Christmas Day, we’ve been playing with boxes rather than thinking about what might be in them. So let’s take a quick look at a more realistic layout, in order to see why the CSS3 grid layout module can be really useful. At this time of year, I am very excited to get out of storage my collection of odd nativity sets, prompting my family to suggest I might want to open a museum. Should I ever do so, I’ll need a website, and here is an example layout.
As I am using CSS3 grid layout, I can order my source in a logical manner. In this example my document is as follows, though these elements could be in any order I please:
<div class="wrapper">
<div class="welcome">
...
</div>
<article class="main">
...
</article>
<div class="info">
...
</div>
<div class="ads">
...
</div>
</div>
For wide viewports I can use grid layout to create a sidebar, with the important information about opening times on the top righ,t with the ads displayed below it. This creates the layout shown in the screenshot above.
@media only screen and (min-width: 940px) {
.wrapper {
-ms-grid-columns:~" 1fr (4.25fr 1fr)[16]";
-ms-grid-rows:~" (auto 20px)[24]";
}
.welcome {
.position(1,1,12,1);
padding: 0 5% 0 0;
}
.info {
.position(13,1,4,1);
border: 0;
padding:0;
}
.main {
.position(1,2,12,1);
padding: 0 5% 0 0;
}
.ads {
.position(13,2,4,1);
display: block;
margin-left: 0;
}
}
In a floated layout, a sidebar like this often ends up being placed under the main content at smaller screen widths. For my situation this is less than ideal. I want the important information about opening times to end up above the main article, and to push the ads below it. With grid layout I can easily achieve this at the smallest width .info ends up in row two and .ads in row five with the article between.
.wrapper {
display: ~"-ms-grid";
-ms-grid-columns: ~"1fr (4.25fr 1fr)[4]";
-ms-grid-rows: ~"(auto 20px)[40]";
}
.welcome {
.position(1,1,4,1);
}
.info {
.position(1,2,4,1);
border: 4px solid #fff;
padding: 10px;
}
.content {
.position(1,3,4,5);
}
.main {
.position(1,3,4,1);
}
.ads {
.position(1,4,4,1);
}
Finally, as an extra tweak I add in a breakpoint at 600 pixels and nest a second grid on the ads area, arranging those three images into a row when they sit below the article at a screen width wider than the very narrow mobile width but still too narrow to support a sidebar.
@media only screen and (min-width: 600px) {
.ads {
display: ~"-ms-grid";
-ms-grid-columns: ~"20px 1fr 20px 1fr 20px 1fr";
-ms-grid-rows: ~"1fr";
margin-left: -20px;
}
.ad:nth-child(1) {
.position(1,1,1,1);
}
.ad:nth-child(2) {
.position(2,1,1,1);
}
.ad:nth-child(3) {
.position(3,1,1,1);
}
}
View example four in Internet Explorer 10.
This is a very simple example to show how we can use CSS grid layout without needing to add a lot of classes to our document. It also demonstrates how we can mainpulate the content depending on the context in which the user is viewing it.
Layout, source order and the idea of content priority
CSS3 grid layout isn’t the only module that starts to move us away from the issue of visual layout being linked to source order. However, with good support in Internet Explorer 10, it is a nice way to start looking at how this might work. If you look at the grid layout module as something to be used in conjunction with the flexible box layout module and the very interesting CSS regions and exclusions specifications, we have, tantalizingly on the horizon, a powerful set of tools for layout.
I am particularly keen on the potential separation of source order from layout as it dovetails rather neatly into something I spend a lot of time thinking about. As a CMS developer, working on larger scale projects as well as our CMS product Perch, I am interested in how we better enable content editors to create content for the web. In particular, I search for better ways to help them create adaptive content; content that will work in a variety of contexts rather than being tied to one representation of that content.
If the concept of adaptive content is new to you, then Karen McGrane’s presentation Adapting Ourselves to Adaptive Content is the place to start. Karen talks about needing to think of content as chunks, that might be used in many different places, displayed differently depending on context.
I absolutely agree with Karen’s approach to content. We have always attempted to move content editors away from thinking about creating a page and previewing it on the desktop. However at some point content does need to be published as a page, or a collection of content if you prefer, and bits of that content have priority. Particularly in a small screen context, content gets linearized, we can only show so much at a time, and we need to make sure important content rises to the top. In the case of my example, I wanted to ensure that the address information was clearly visible without scrolling around too much. Dropping it with the entire sidebar to the bottom of the page would not have been so helpful, though neither would moving the whole sidebar to the top of the screen so a visitor had to scroll past advertising to get to the article.
If our layout is linked to our source order, then enabling the content editor to make decisions about priority is really hard. Only a system that can do some regeneration of the source order on the server-side – perhaps by way of multiple templates – can allow those kinds of decisions to be made. For larger systems this might be a possibility; for smaller ones, or when using an off-the-shelf CMS, it is less likely to be. Fortunately, any system that allows some form of custom field type can be used to pop a class on to an element, and with CSS grid layout that is all that is needed to be able to target that element and drop it into the right place when the content is viewed, be that on a desktop or a mobile device.
This approach can move us away from forcing editors to think visually. At the moment, I might have to explain to an editor that if a certain piece of content needs to come first when viewed on a mobile device, it needs to be placed in the sidebar area, tying it to a particular layout and design. I have to do this because we have to enforce fairly strict rules around source order to make the mechanics of the responsive design work. If I can instead advise an editor to flag important content as high priority in the CMS, then I can make decisions elsewhere as to how that is displayed, and we can maintain the visual hierarchy across all the different ways content might be rendered.
Why frustrate ourselves with specifications we can’t yet use in production?
The CSS3 grid layout specification is listed under the Exploring section of the list of current work of the CSS Working Group. While discussing a module at this stage might seem a bit pointless if we can’t use it in production work, there is a very real reason for doing so. If those of us who will ultimately be developing sites with these tools find out about them early enough, then we can start to give our feedback to the people responsible for the specification. There is information on the same page about how to get involved with the disussions.
So, if you have a bit of time this holiday season, why not have a play with the CSS3 grid layout module? I have outlined here some of my thoughts on how grid layout and other modules that separate layout from source order can be used in the work that I do. Likewise, wherever in the stack you work, playing with and thinking about new specifications means you can think about how you would use them to enhance your work. Spot a problem? Think that a change to the specification would improve things for a specific use case? Then you have something you could post to www-style to add to the discussion around this module.
All the examples are on CodePen so feel free to play around and fork them. |
2012 |
Rachel Andrew |
rachelandrew |
2012-12-18T00:00:00+00:00 |
https://24ways.org/2012/css3-grid-layout/ |
code |
| 180 |
Going Nuts with CSS Transitions |
I’m going to show you how CSS 3 transforms and WebKit transitions can add zing to the way you present images on your site.
Laying the foundations
First we are going to make our images look like mini polaroids with captions. Here’s the markup:
<div class="polaroid pull-right">
<img src="../img/seal.jpg" alt="">
<p class="caption">Found this little cutie on a walk in New Zealand!</p>
</div>
You’ll notice we’re using a somewhat presentational class of pull-right here. This means the logic is kept separate from the code that applies the polaroid effect. The polaroid class has no positioning, which allows it to be used generically anywhere that the effect is required. The pull classes set a float and add appropriate margins—they can be used for things like blockquotes as well.
.polaroid {
width: 150px;
padding: 10px 10px 20px 10px;
border: 1px solid #BFBFBF;
background-color: white;
-webkit-box-shadow: 2px 2px 3px rgba(135, 139, 144, 0.4);
-moz-box-shadow: 2px 2px 3px rgba(135, 139, 144, 0.4);
box-shadow: 2px 2px 3px rgba(135, 139, 144, 0.4);
}
The actual polaroid effect itself is simply applied using padding, a border and a background colour. We also apply a nice subtle box shadow, using a property that is supported by modern WebKit browsers and Firefox 3.5+. We include the box-shadow property last to ensure that future browsers that support the eventual CSS3 specified version natively will use that implementation over the legacy browser specific version.
The box-shadow property takes four values: three lengths and a colour. The first is the horizontal offset of the shadow—positive values place the shadow on the right, while negative values place it to the left. The second is the vertical offset, positive meaning below. If both of these are set to 0, the shadow is positioned equally on all four sides. The last length value sets the blur radius—the larger the number, the blurrier the shadow (therefore the darker you need to make the colour to have an effect).
The colour value can be given in any format recognised by CSS. Here, we’re using rgba as explained by Drew behind the first door of this year’s calendar.
Rotation
For browsers that understand it (currently our old favourites WebKit and FF3.5+) we can add some visual flair by rotating the image, using the transform CSS 3 property.
-webkit-transform: rotate(9deg);
-moz-transform: rotate(9deg);
transform: rotate(9deg);
Rotations can be specified in degrees, radians (rads) or grads. WebKit also supports turns unfortunately Firefox doesn’t just yet.
For our example, we want any polaroid images on the left hand side to be rotated in the opposite direction, using a negative degree value:
.pull-left.polaroid {
-webkit-transform: rotate(-9deg);
-moz-transform: rotate(-9deg);
transform: rotate(-9deg);
}
Multiple class selectors don’t work in IE6 but as luck would have it, the transform property doesn’t work in any current IE version either. The above code is a good example of progressive enrichment: browsers that don’t support box-shadow or transform will still see the image and basic polaroid effect.
Animation
WebKit is unique amongst browser rendering engines in that it allows animation to be specified in pure CSS. Although this may never actually make it in to the CSS 3 specification, it degrades nicely and more importantly is an awful lot of fun!
Let’s go nuts.
In the next demo, the image is contained within a link and mousing over that link causes the polaroid to animate from being angled to being straight.
Here’s our new markup:
<a href="http://www.flickr.com/photos/nataliedowne/2340993237/" class="polaroid">
<img src="../img/raft.jpg" alt="">
White water rafting in Queenstown
</a>
And here are the relevant lines of CSS:
a.polaroid {
/* ... */
-webkit-transform: rotate(10deg);
-webkit-transition: -webkit-transform 0.5s ease-in;
}
a.polaroid:hover,
a.polaroid:focus,
a.polaroid:active {
/* ... */
-webkit-transform: rotate(0deg);
}
The @-webkit-transition@ property is the magic wand that sets up the animation. It takes three values: the property to be animated, the duration of the animation and a ‘timing function’ (which affects the animation’s acceleration, for a smoother effect).
-webkit-transition only takes affect when the specified property changes. In pure CSS, this is done using dynamic pseudo-classes. You can also change the properties using JavaScript, but that’s a story for another time.
Throwing polaroids at a table
Imagine there are lots of differently sized polaroid photos scattered on a table. That’s the effect we are aiming for with our next demo.
As an aside: we are using absolute positioning to arrange the images inside a flexible width container (with a minimum and maximum width specified in pixels). As some are positioned from the left and some from the right when you resize the browser they shuffle underneath each other. This is an effect used on the UX London site.
This demo uses a darker colour shadow with more transparency than before. The grey shadow in the previous example worked fine, but it was against a solid background. Since the images are now overlapping each other, the more opaque shadow looked fake.
-webkit-box-shadow: 2px 2px 4px rgba(0,0, 0, 0.3);
-moz-box-shadow: 2px 2px 4px rgba(0,0, 0, 0.3);
box-shadow: 2px 2px 4px rgba(0,0, 0, 0.3);
On hover, as well as our previous trick of animating the image rotation back to straight, we are also making the shadow darker and setting the z-index to be higher than the other images so that it appears on top.
And Finally…
Finally, for a bit more fun, we’re going to simulate the images coming towards you and lifting off the page. We’ll achieve this by making them grow larger and by offsetting the shadow & making it longer.
Screenshot 1 shows the default state, while 2 shows our previous hover effect. Screenshot 3 is the effect we are aiming for, illustrated by demo 4.
a.polaroid {
/* ... */
z-index: 2;
-webkit-box-shadow: 2px 2px 4px rgba(0,0, 0, 0.3);
-moz-box-shadow: 2px 2px 4px rgba(0,0, 0, 0.3);
box-shadow: 2px 2px 4px rgba(0,0, 0, 0.3);
-webkit-transform: rotate(10deg);
-moz-transform: rotate(10deg);
transform: rotate(10deg);
-webkit-transition: all 0.5s ease-in;
}
a.polaroid:hover,
a.polaroid:focus,
a.polaroid:active {
z-index: 999;
border-color: #6A6A6A;
-webkit-box-shadow: 15px 15px 20px rgba(0,0, 0, 0.4);
-moz-box-shadow: 15px 15px 20px rgba(0,0, 0, 0.4);
box-shadow: 15px 15px 20px rgba(0,0, 0, 0.4);
-webkit-transform: rotate(0deg) scale(1.05);
-moz-transform: rotate(0deg) scale(1.05);
transform: rotate(0deg) scale(1.05);
}
You’ll notice we are now giving the transform property another transform function: scale, which takes increases the size by the specified factor. Other things you can do with transform include skewing, translating or you can go mad creating your own transforms with a matrix.
The box-shadow has both its offset and blur radius increased dramatically, and is darkened using the alpha channel of the rgba colour.
And because we want the effects to all animate smoothly, we pass a value of all to the -webkit-transition property, ensuring that any changed property on that link will be animated.
Demo 5 is the finished example, bringing everything nicely together.
CSS transitions and transforms are a great example of progressive enrichment, which means improving the experience for a portion of the audience without negatively affecting other users. They are also a lot of fun to play with!
Further reading
-moz-transform – the mozilla developer center has a comprehensive explanation of transform that also applies to -webkit-transform and transform.
CSS: Animation Using CSS Transforms – this is a good, more indepth tutorial on animations.
CSS Animation – the Safari blog explains the usage of -webkit-transform.
Dinky pocketbooks with transform – another use for transforms, create your own printable pocketbook.
A while back, Simon wrote a little bookmarklet to spin the entire page… warning: this will spin the entire page. |
2009 |
Natalie Downe |
nataliedowne |
2009-12-14T00:00:00+00:00 |
https://24ways.org/2009/going-nuts-with-css-transitions/ |
code |
| 68 |
Grid, Flexbox, Box Alignment: Our New System for Layout |
Three years ago for 24 ways 2012, I wrote an article about a new CSS layout method I was excited about. A specification had emerged, developed by people from the Internet Explorer team, bringing us a proper grid system for the web. In 2015, that Internet Explorer implementation is still the only public implementation of CSS grid layout. However, in 2016 we should be seeing it in a new improved form ready for our use in browsers.
Grid layout has developed hidden behind a flag in Blink, and in nightly builds of WebKit and, latterly, Firefox. By being developed in this way, breaking changes could be safely made to the specification as no one was relying on the experimental implementations in production work.
Another new layout method has emerged over the past few years in a more public and perhaps more painful way. Shipped prefixed in browsers, The flexible box layout module (flexbox) was far too tempting for developers not to use on production sites. Therefore, as changes were made to the specification, we found ourselves with three different flexboxes, and browser implementations that did not match one another in completeness or in the version of specified features they supported.
Owing to the different ways these modules have come into being, when I present on grid layout it is often the very first time someone has heard of the specification. A question I keep being asked is whether CSS grid layout and flexbox are competing layout systems, as though it might be possible to back the loser in a CSS layout competition. The reality, however, is that these two methods will sit together as one system for doing layout on the web, each method playing to certain strengths and serving particular layout tasks.
If there is to be a loser in the battle of the layouts, my hope is that it will be the layout frameworks that tie our design to our markup. They have been a necessary placeholder while we waited for a true web layout system, but I believe that in a few years time we’ll be easily able to date a website to circa 2015 by seeing <div class="row"> or <div class="col-md-3"> in the markup.
In this article, I’m going to take a look at the common features of our new layout systems, along with a couple of examples which serve to highlight the differences between them.
To see the grid layout examples you will need to enable grid in your browser. The easiest thing to do is to enable the experimental web platform features flag in Chrome. Details of current browser support can be found here.
Relationship
Items only become flex or grid items if they are a direct child of the element that has display:flex, display:grid or display:inline-grid applied. Those direct children then understand themselves in the context of the complete layout. This makes many things possible. It’s the lack of relationship between elements that makes our existing layout methods difficult to use. If we float two columns, left and right, we have no way to tell the shorter column to extend to the height of the taller one. We have expended a lot of effort trying to figure out the best way to make full-height columns work, using techniques that were never really designed for page layout.
At a very simple level, the relationship between elements means that we can easily achieve full-height columns. In flexbox:
See the Pen Flexbox equal height columns by rachelandrew (@rachelandrew) on CodePen.
And in grid layout (requires a CSS grid-supporting browser):
See the Pen Grid equal height columns by rachelandrew (@rachelandrew) on CodePen.
Alignment
Full-height columns rely on our flex and grid items understanding themselves as part of an overall layout. They also draw on a third new specification: the box alignment module. If vertical centring is a gift you’d like to have under your tree this Christmas, then this is the box you’ll want to unwrap first.
The box alignment module takes the alignment and space distribution properties from flexbox and applies them to other layout methods. That includes grid layout, but also other layout methods. Once implemented in browsers, this specification will give us true vertical centring of all the things.
Our examples above achieved full-height columns because the default value of align-items is stretch. The value ensured our columns stretched to the height of the tallest. If we want to use our new vertical centring abilities on all items, we would set align-items:center on the container. To align one flex or grid item, apply the align-self property.
The examples below demonstrate these alignment properties in both grid layout and flexbox. The portrait image of Widget the cat is aligned with the default stretch. The other three images are aligned using different values of align-self.
Take a look at an example in flexbox:
See the Pen Flexbox alignment by rachelandrew (@rachelandrew) on CodePen.
And also in grid layout (requires a CSS grid-supporting browser):
See the Pen Grid alignment by rachelandrew (@rachelandrew) on CodePen.
The alignment properties used with CSS grid layout.
Fluid grids
A cornerstone of responsive design is the concept of fluid grids.
“[…]every aspect of the grid—and the elements laid upon it—can be expressed as a proportion relative to its container.”
—Ethan Marcotte, “Fluid Grids”
The method outlined by Marcotte is to divide the target width by the context, then use that value as a percentage value for the width property on our element.
h1 {
margin-left: 14.575%; /* 144px / 988px = 0.14575 */
width: 70.85%; /* 700px / 988px = 0.7085 */
}
In more recent years, we’ve been able to use calc() to simplify this (at least, for those of us able to drop support for Internet Explorer 8). However, flexbox and grid layout make fluid grids simple.
The most basic of flexbox demos shows this fluidity in action. The justify-content property – another property defined in the box alignment module – can be used to create an equal amount of space between or around items. As the available width increases, more space is assigned in proportion.
In this demo, the list items are flex items due to display:flex being added to the ul. I have given them a maximum width of 250 pixels. Any remaining space is distributed equally between the items as the justify-content property has a value of space-between.
See the Pen Flexbox: justify-content by rachelandrew (@rachelandrew) on CodePen.
For true fluid grid-like behaviour, your new flexible friends are flex-grow and flex-shrink. These properties give us the ability to assign space in proportion.
The flexbox flex property is a shorthand for:
flex-grow
flex-shrink
flex-basis
The flex-basis property sets the default width for an item. If flex-grow is set to 0, then the item will not grow larger than the flex-basis value; if flex-shrink is 0, the item will not shrink smaller than the flex-basis value.
flex: 1 1 200px: a flexible box that can grow and shrink from a 200px basis.
flex: 0 0 200px: a box that will be 200px and cannot grow or shrink.
flex: 1 0 200px: a box that can grow bigger than 200px, but not shrink smaller.
In this example, I have a set of boxes that can all grow and shrink equally from a 100 pixel basis.
See the Pen Flexbox: flex-grow by rachelandrew (@rachelandrew) on CodePen.
What I would like to happen is for the first element, containing a portrait image, to take up less width than the landscape images, thus keeping it more in proportion. I can do this by changing the flex-grow value. By giving all the items a value of 1, they all gain an equal amount of the available space after the 100 pixel basis has been worked out.
If I give them all a value of 3 and the first box a value of 1, the other boxes will be assigned three parts of the available space while box 1 is assigned only one part. You can see what happens in this demo:
See the Pen Flexbox: flex-grow by rachelandrew (@rachelandrew) on CodePen.
Once you understand flex-grow, you should easily be able to grasp how the new fraction unit (fr, defined in the CSS grid layout specification) works. Like flex-grow, this unit allows us to assign available space in proportion. In this case, we assign the space when defining our track sizes.
In this demo (which requires a CSS grid-supporting browser), I create a four-column grid using the fraction unit to define my track sizes. The first track is 1fr in width, and the others 2fr.
grid-template-columns: 1fr 2fr 2fr 2fr;
See the Pen Grid fraction units by rachelandrew (@rachelandrew) on CodePen.
The four-track grid.
Separation of concerns
My younger self petitioned my peers to stop using tables for layout and to move to CSS. One of the rallying cries of that movement was the concept of separating our source and content from how they were displayed. It was something of a failed promise given the tools we had available: the display leaked into the markup with the need for redundant elements to cope with browser bugs, or visual techniques that just could not be achieved without supporting markup.
Browsers have improved, but even now we can find ourselves compromising the ideal document structure so we can get the layout we want at various breakpoints. In some ways, the situation has returned to tables-for-layout days. Many of the current grid frameworks rely on describing our layout directly in the markup. We add divs for rows, and classes to describe the number of desired columns. We nest these constructions of divs inside one another.
Here is a snippet from the Bootstrap grid examples – two columns with two nested columns:
<div class="row">
<div class="col-md-8">
.col-md-8
<div class="row">
<div class="col-md-6">
.col-md-6
</div>
<div class="col-md-6">
.col-md-6
</div>
</div>
</div>
<div class="col-md-4">
.col-md-4
</div>
</div>
Not a million miles away from something I might have written in 1999.
<table>
<tr>
<td class="col-md-8">
.col-md-8
<table>
<tr>
<td class="col-md-6">
.col-md-6
</td>
<td class="col-md-6">
.col-md-6
</td>
</tr>
</table>
</td>
<td class="col-md-4">
.col-md-4
</td>
</tr>
</table>
Grid and flexbox layouts do not need to be described in markup. The layout description happens entirely in the CSS, meaning that elements can be moved around from within the presentation layer.
Flexbox gives us the ability to reverse the flow of elements, but also to set the order of elements with the order property. This is demonstrated here, where Widget the cat is in position 1 in the source, but I have used the order property to display him after the things that are currently unimpressive to him.
See the Pen Flexbox: order by rachelandrew (@rachelandrew) on CodePen.
Grid layout takes this a step further. Where flexbox lets us set the order of items in a single dimension, grid layout gives us the ability to position things in two dimensions: both rows and columns. Defined in the CSS, this positioning can be changed at any breakpoint without needing additional markup. Compare the source order with the display order in this example (requires a CSS grid-supporting browser):
See the Pen Grid positioning in two dimensions by rachelandrew (@rachelandrew) on CodePen.
Laying out our items in two dimensions using grid layout.
As these demos show, a straightforward way to decide if you should use grid layout or flexbox is whether you want to position items in one dimension or two. If two, you want grid layout.
A note on accessibility and reordering
The issues arising from this powerful ability to change the way items are ordered visually from how they appear in the source have been the subject of much discussion. The current flexbox editor’s draft states
“Authors must use order only for visual, not logical, reordering of content. Style sheets that use order to perform logical reordering are non-conforming.”
—CSS Flexible Box Layout Module Level 1, Editor’s Draft (3 December 2015)
This is to ensure that non-visual user agents (a screen reader, for example) can rely on the document source order as being correct. Take care when reordering that you do so from the basis of a sound document that makes sense in terms of source order. Avoid using visual order to convey meaning.
Automatic content placement with rules
Having control over the order of items, or placing items on a predefined grid, is nice. However, we can often do that already with one method or another and we have frameworks and tools to help us. Tools such as Susy mean we can even get away from stuffing our markup full of grid classes. However, our new layout methods give us some interesting new possibilities.
Something that is useful to be able to do when dealing with content coming out of a CMS or being pulled from some other source, is to define a bunch of rules and then say, “Display this content, using these rules.”
As an example of this, I will leave you with a Christmas poem displayed in a document alongside Widget the cat and some of the decorations that are bringing him no Christmas cheer whatsoever.
The poem is displayed first in the source as a set of paragraphs. I’ve added a class identifying each of the four paragraphs but they are displayed in the source as one text. Below that are all my images, some landscape and some portrait; I’ve added a class of landscape to the landscape ones.
The mobile-first grid is a single column and I use line-based placement to explicitly position my poem paragraphs. The grid layout auto-placement rules then take over and place the images into the empty cells left in the grid.
At wider screen widths, I declare a four-track grid, and position my poem around the grid, keeping it in a readable order.
I also add rules to my landscape class, stating that these items should span two tracks. Once again the grid layout auto-placement rules position the rest of my images without my needing to position them. You will see that grid layout takes items out of source order to fill gaps in the grid. It does this because I have set the property grid-auto-flow to dense. The default is sparse meaning that grid will not attempt this backfilling behaviour.
Take a look and play around with the full demo (requires a CSS grid layout-supporting browser):
See the Pen Grid auto-flow with rules by rachelandrew (@rachelandrew) on CodePen.
The final automatic placement example.
My wish for 2016
I really hope that in 2016, we will see CSS grid layout finally emerge from behind browser flags, so that we can start to use these features in production — that we can start to move away from using the wrong tools for the job.
However, I also hope that we’ll see developers fully embracing these tools as the new system that they are. I want to see people exploring the possibilities they give us, rather than trying to get them to behave like the grid systems of 2015. As you discover these new modules, treat them as the new paradigm that they are, get creative with them. And, as you find the edges of possibility with them, take that feedback to the CSS Working Group. Help improve the layout systems that will shape the look of the future web.
Some further reading
I maintain a site of grid layout examples and resources at Grid by Example.
The three CSS specifications I’ve discussed can be found as editor’s drafts: CSS grid, flexbox, box alignment.
I wrote about the last three years of my interest in CSS grid layout, which gives something of a history of the specification.
More examples of box alignment and grid layout.
My presentation at Fronteers earlier this year, in which I explain more about these concepts. |
2015 |
Rachel Andrew |
rachelandrew |
2015-12-15T00:00:00+00:00 |
https://24ways.org/2015/grid-flexbox-box-alignment-our-new-system-for-layout/ |
code |
| 18 |
Grunt for People Who Think Things Like Grunt are Weird and Hard |
Front-end developers are often told to do certain things:
Work in as small chunks of CSS and JavaScript as makes sense to you, then concatenate them together for the production website.
Compress your CSS and minify your JavaScript to make their file sizes as small as possible for your production website.
Optimize your images to reduce their file size without affecting quality.
Use Sass for CSS authoring because of all the useful abstraction it allows.
That’s not a comprehensive list of course, but those are the kind of things we need to do. You might call them tasks.
I bet you’ve heard of Grunt. Well, Grunt is a task runner. Grunt can do all of those things for you. Once you’ve got it set up, which isn’t particularly difficult, those things can happen automatically without you having to think about them again.
But let’s face it: Grunt is one of those fancy newfangled things that all the cool kids seem to be using but at first glance feels strange and intimidating. I hear you. This article is for you.
Let’s nip some misconceptions in the bud right away
Perhaps you’ve heard of Grunt, but haven’t done anything with it. I’m sure that applies to many of you. Maybe one of the following hang-ups applies to you.
I don’t need the things Grunt does
You probably do, actually. Check out that list up top. Those things aren’t nice-to-haves. They are pretty vital parts of website development these days. If you already do all of them, that’s awesome. Perhaps you use a variety of different tools to accomplish them. Grunt can help bring them under one roof, so to speak. If you don’t already do all of them, you probably should and Grunt can help. Then, once you are doing those, you can keep using Grunt to do more for you, which will basically make you better at doing your job.
Grunt runs on Node.js — I don’t know Node
You don’t have to know Node. Just like you don’t have to know Ruby to use Sass. Or PHP to use WordPress. Or C++ to use Microsoft Word.
I have other ways to do the things Grunt could do for me
Are they all organized in one place, configured to run automatically when needed, and shared among every single person working on that project? Unlikely, I’d venture.
Grunt is a command line tool — I’m just a designer
I’m a designer too. I prefer native apps with graphical interfaces when I can get them. But I don’t think that’s going to happen with Grunt1.
The extent to which you need to use the command line is:
Navigate to your project’s directory.
Type grunt and press Return.
After set-up, that is, which again isn’t particularly difficult.
OK. Let’s get Grunt installed
Node is indeed a prerequisite for Grunt. If you don’t have Node installed, don’t worry, it’s very easy. You literally download an installer and run it. Click the big Install button on the Node website.
You install Grunt on a per-project basis. Go to your project’s folder. It needs a file there named package.json at the root level. You can just create one and put it there.
package.json at root
The contents of that file should be this:
{
"name": "example-project",
"version": "0.1.0",
"devDependencies": {
"grunt": "~0.4.1"
}
}
Feel free to change the name of the project and the version, but the devDependencies thing needs to be in there just like that.
This is how Node does dependencies. Node has a package manager called NPM (Node packaged modules) for managing Node dependencies (like a gem for Ruby if you’re familiar with that). You could even think of it a bit like a plug-in for WordPress.
Once that package.json file is in place, go to the terminal and navigate to your folder. Terminal rubes like me do it like this:
Terminal rube changing directories
Then run the command:
npm install
After you’ve run that command, a new folder called node_modules will show up in your project.
Example of node_modules folder
The other files you see there, README.md and LICENSE are there because I’m going to put this project on GitHub and that’s just standard fare there.
The last installation step is to install the Grunt CLI (command line interface). That’s what makes the grunt command in the terminal work. Without it, typing grunt will net you a “Command Not Found”-style error. It is a separate installation for efficiency reasons. Otherwise, if you had ten projects you’d have ten copies of Grunt CLI.
This is a one-liner again. Just run this command in the terminal:
npm install -g grunt-cli
You should close and reopen the terminal as well. That’s a generic good practice to make sure things are working right. Kinda like restarting your computer after you install a new application was in the olden days.
Let’s make Grunt concatenate some files
Perhaps in our project there are three separate JavaScript files:
jquery.js – The library we are using.
carousel.js – A jQuery plug-in we are using.
global.js – Our authored JavaScript file where we configure and call the plug-in.
In production, we would concatenate all those files together for performance reasons (one request is better than three). We need to tell Grunt to do this for us.
But wait. Grunt actually doesn’t do anything all by itself. Remember Grunt is a task runner. The tasks themselves we will need to add. We actually haven’t set up Grunt to do anything yet, so let’s do that.
The official Grunt plug-in for concatenating files is grunt-contrib-concat. You can read about it on GitHub if you want, but all you have to do to use it on your project is to run this command from the terminal (it will henceforth go without saying that you need to run the given commands from your project’s root folder):
npm install grunt-contrib-concat --save-dev
A neat thing about doing it this way: your package.json file will automatically be updated to include this new dependency. Open it up and check it out. You’ll see a new line:
"grunt-contrib-concat": "~0.3.0"
Now we’re ready to use it. To use it we need to start configuring Grunt and telling it what to do.
You tell Grunt what to do via a configuration file named Gruntfile.js2
Just like our package.json file, our Gruntfile.js has a very special format that must be just right. I wouldn’t worry about what every word of this means. Just check out the format:
module.exports = function(grunt) {
// 1. All configuration goes here
grunt.initConfig({
pkg: grunt.file.readJSON('package.json'),
concat: {
// 2. Configuration for concatinating files goes here.
}
});
// 3. Where we tell Grunt we plan to use this plug-in.
grunt.loadNpmTasks('grunt-contrib-concat');
// 4. Where we tell Grunt what to do when we type "grunt" into the terminal.
grunt.registerTask('default', ['concat']);
};
Now we need to create that configuration. The documentation can be overwhelming. Let’s focus just on the very simple usage example.
Remember, we have three JavaScript files we’re trying to concatenate. We’ll list file paths to them under src in an array of file paths (as quoted strings) and then we’ll list a destination file as dest. The destination file doesn’t have to exist yet. It will be created when this task runs and squishes all the files together.
Both our jquery.js and carousel.js files are libraries. We most likely won’t be touching them. So, for organization, we’ll keep them in a /js/libs/ folder. Our global.js file is where we write our own code, so that will be right in the /js/ folder. Now let’s tell Grunt to find all those files and squish them together into a single file named production.js, named that way to indicate it is for use on our real live website.
concat: {
dist: {
src: [
'js/libs/*.js', // All JS in the libs folder
'js/global.js' // This specific file
],
dest: 'js/build/production.js',
}
}
Note: throughout this article there will be little chunks of configuration code like above. The intention is to focus in on the important bits, but it can be confusing at first to see how a particular chunk fits into the larger file. If you ever get confused and need more context, refer to the complete file.
With that concat configuration in place, head over to the terminal, run the command:
grunt
and watch it happen! production.js will be created and will be a perfect concatenation of our three files. This was a big aha! moment for me. Feel the power course through your veins. Let’s do more things!
Let’s make Grunt minify that JavaScript
We have so much prep work done now, adding new tasks for Grunt to run is relatively easy. We just need to:
Find a Grunt plug-in to do what we want
Learn the configuration style of that plug-in
Write that configuration to work with our project
The official plug-in for minifying code is grunt-contrib-uglify. Just like we did last time, we just run an NPM command to install it:
npm install grunt-contrib-uglify --save-dev
Then we alter our Gruntfile.js to load the plug-in:
grunt.loadNpmTasks('grunt-contrib-uglify');
Then we configure it:
uglify: {
build: {
src: 'js/build/production.js',
dest: 'js/build/production.min.js'
}
}
Let’s update that default task to also run minification:
grunt.registerTask('default', ['concat', 'uglify']);
Super-similar to the concatenation set-up, right?
Run grunt at the terminal and you’ll get some deliciously minified JavaScript:
Minified JavaScript
That production.min.js file is what we would load up for use in our index.html file.
Let’s make Grunt optimize our images
We’ve got this down pat now. Let’s just go through the motions. The official image minification plug-in for Grunt is grunt-contrib-imagemin. Install it:
npm install grunt-contrib-imagemin --save-dev
Register it in the Gruntfile.js:
grunt.loadNpmTasks('grunt-contrib-imagemin');
Configure it:
imagemin: {
dynamic: {
files: [{
expand: true,
cwd: 'images/',
src: ['**/*.{png,jpg,gif}'],
dest: 'images/build/'
}]
}
}
Make sure it runs:
grunt.registerTask('default', ['concat', 'uglify', 'imagemin']);
Run grunt and watch that gorgeous squishification happen:
Squished images
Gotta love performance increases for nearly zero effort.
Let’s get a little bit smarter and automate
What we’ve done so far is awesome and incredibly useful. But there are a couple of things we can get smarter on and make things easier on ourselves, as well as Grunt:
Run these tasks automatically when they should
Run only the tasks needed at the time
For instance:
Concatenate and minify JavaScript when JavaScript changes
Optimize images when a new image is added or an existing one changes
We can do this by watching files. We can tell Grunt to keep an eye out for changes to specific places and, when changes happen in those places, run specific tasks. Watching happens through the official grunt-contrib-watch plugin.
I’ll let you install it. It is exactly the same process as the last few plug-ins we installed. We configure it by giving watch specific files (or folders, or both) to watch. By watch, I mean monitor for file changes, file deletions or file additions. Then we tell it what tasks we want to run when it detects a change.
We want to run our concatenation and minification when anything in the /js/ folder changes. When it does, we should run the JavaScript-related tasks. And when things happen elsewhere, we should not run the JavaScript-related tasks, because that would be irrelevant. So:
watch: {
scripts: {
files: ['js/*.js'],
tasks: ['concat', 'uglify'],
options: {
spawn: false,
},
}
}
Feels pretty comfortable at this point, hey? The only weird bit there is the spawn thing. And you know what? I don’t even really know what that does. From what I understand from the documentation it is the smart default. That’s real-world development. Just leave it alone if it’s working and if it’s not, learn more.
Note: Isn’t it frustrating when something that looks so easy in a tutorial doesn’t seem to work for you? If you can’t get Grunt to run after making a change, it’s very likely to be a syntax error in your Gruntfile.js. That might look like this in the terminal:
Errors running Grunt
Usually Grunt is pretty good about letting you know what happened, so be sure to read the error message. In this case, a syntax error in the form of a missing comma foiled me. Adding the comma allowed it to run.
Let’s make Grunt do our preprocessing
The last thing on our list from the top of the article is using Sass — yet another task Grunt is well-suited to run for us. But wait? Isn’t Sass technically in Ruby? Indeed it is. There is a version of Sass that will run in Node and thus not add an additional dependency to our project, but it’s not quite up-to-snuff with the main Ruby project. So, we’ll use the official grunt-contrib-sass plug-in which just assumes you have Sass installed on your machine. If you don’t, follow the command line instructions.
What’s neat about Sass is that it can do concatenation and minification all by itself. So for our little project we can just have it compile our main global.scss file:
sass: {
dist: {
options: {
style: 'compressed'
},
files: {
'css/build/global.css': 'css/global.scss'
}
}
}
We wouldn’t want to manually run this task. We already have the watch plug-in installed, so let’s use it! Within the watch configuration, we’ll add another subtask:
css: {
files: ['css/*.scss'],
tasks: ['sass'],
options: {
spawn: false,
}
}
That’ll do it. Now, every time we change any of our Sass files, the CSS will automaticaly be updated.
Let’s take this one step further (it’s absolutely worth it) and add LiveReload. With LiveReload, you won’t have to go back to your browser and refresh the page. Page refreshes happen automatically and in the case of CSS, new styles are injected without a page refresh (handy for heavily state-based websites).
It’s very easy to set up, since the LiveReload ability is built into the watch plug-in. We just need to:
Install the browser plug-in
Add to the top of the watch configuration:
. watch: {
options: {
livereload: true,
},
scripts: {
/* etc */
Restart the browser and click the LiveReload icon to activate it.
Update some Sass and watch it change the page automatically.
Live reloading browser
Yum.
Prefer a video?
If you’re the type that likes to learn by watching, I’ve made a screencast to accompany this article that I’ve published over on CSS-Tricks: First Moments with Grunt
Leveling up
As you might imagine, there is a lot of leveling up you can do with your build process. It surely could be a full time job in some organizations.
Some hardcore devops nerds might scoff at the simplistic setup we have going here. But I’d advise them to slow their roll. Even what we have done so far is tremendously valuable. And don’t forget this is all free and open source, which is amazing.
You might level up by adding more useful tasks:
Running your CSS through Autoprefixer (A+ Would recommend) instead of a preprocessor add-ons.
Writing and running JavaScript unit tests (example: Jasmine).
Build your image sprites and SVG icons automatically (example: Grunticon).
Start a server, so you can link to assets with proper file paths and use services that require a real URL like TypeKit and such, as well as remove the need for other tools that do this, like MAMP.
Check for code problems with HTML-Inspector, CSS Lint, or JS Hint.
Have new CSS be automatically injected into the browser when it ever changes.
Help you commit or push to a version control repository like GitHub.
Add version numbers to your assets (cache busting).
Help you deploy to a staging or production environment (example: DPLOY).
You might level up by simply understanding more about Grunt itself:
Read Grunt Boilerplate by Mark McDonnell.
Read Grunt Tips and Tricks by Nicolas Bevacqua.
Organize your Gruntfile.js by splitting it up into smaller files.
Check out other people’s and projects’ Gruntfile.js.
Learn more about Grunt by digging into its source and learning about its API.
Let’s share
I think some group sharing would be a nice way to wrap this up. If you are installing Grunt for the first time (or remember doing that), be especially mindful of little frustrating things you experience(d) but work(ed) through. Those are the things we should share in the comments here. That way we have this safe place and useful resource for working through those confusing moments without the embarrassment. We’re all in this thing together!
1 Maybe someday someone will make a beautiful Grunt app for your operating system of choice. But I’m not sure that day will come. The configuration of the plug-ins is the important part of using Grunt. Each plug-in is a bit different, depending on what it does. That means a uniquely considered UI for every single plug-in, which is a long shot.
Perhaps a decent middleground is this Grunt DevTools Chrome add-on.
2 Gruntfile.js is often referred to as Gruntfile in documentation and examples. Don’t literally name it Gruntfile — it won’t work. |
2013 |
Chris Coyier |
chriscoyier |
2013-12-11T00:00:00+00:00 |
https://24ways.org/2013/grunt-is-not-weird-and-hard/ |
code |
| 80 |
HTML5 Video Bumpers |
Video is a bigger part of the web experience than ever before. With native browser support for HTML5 video elements freeing us from the tyranny of plugins, and the availability of faster internet connections to the workplace, home and mobile networks, it’s now pretty straightforward to publish video in a way that can be consumed in all sorts of ways on all sorts of different web devices.
I recently worked on a project where the client had shot some dedicated video shorts to publish on their site. They also had some five-second motion graphics produced to top and tail the videos with context and branding. This pretty common requirement is a great idea on the web, where a user might land at your video having followed a link and be viewing a page without much context.
Known as bumpers, these short introduction clips help brand a video and make it look a lot more professional.
Adding bumpers to a video
The simplest way to add bumpers to a video would be to edit them on to the start and end of the video file itself. Cooking the bumpers into the video file is easy, but should you ever want to update them it can become a real headache. If the branding needs updating, for example, you’d need to re-edit and re-encode all your videos. Not a fun task.
What if the bumpers could be added dynamically? That would enable you to use the same bumper for multiple videos (decreasing download time for users who might watch more than one) and to update the bumpers whenever you wanted. You could change them seasonally, update them for special promotions, run different advertising slots, perform multivariate testing, or even target different bumpers to different users.
The trade-off, of course, is that if you dynamically add your bumpers, there’s a chance that a user in a given circumstance might not see the bumper. For example, if the main video feature was uploaded to YouTube, you’d have no way to control the playback. As always, you need to weigh up the pros and cons and make your choice.
HTML5 bumpers
If you wanted to dynamically add bumpers to your HTML5 video, how would you go about it? That was the question I found myself needing to answer for this particular client project.
My initial thought was to treat it just like an image slideshow. If I were building a slideshow that moved between images, I’d use CSS absolute positioning with z-index to stack the images up on top of each other in a pile, with the first image on top. To transition to the second image, I’d use JavaScript to fade the top image out, revealing the second image beneath it.
Now that video is just a native object in the DOM, just like an image, why not do the same? Stack the videos up with the opening bumper on top, listen for the video’s onended event, and fade it out to reveal the main feature behind. Good idea, right?
Wrong
Remember that this is the web. It’s never going to be that easy. The problem here is that many non-desktop devices use native, dedicated video players. Think about watching a video on a mobile phone – when you play the video, the phone often goes full-screen in its native player, leaving the web page behind. There’s no opportunity to fade or switch z-index, as the video isn’t being viewed in the page. Your page is left powerless. Powerless!
So what can we do? What can we control?
Those of us with particularly long memories might recall a time before CSS, when we’d have to use JavaScript to perform image rollovers. As CSS background images weren’t a practical reality, we would use lots of <img> elements, and perform a rollover by modifying the src attribute of the image.
Turns out, this old trick of modifying the source can help us out with video, too. In most cases, modifying the src attribute of a <video> element, or perhaps more likely the src attribute of a source element, will swap from one video to another.
Swappin’ it
Let’s take a deliberately simple example of a super-basic video tag:
<video src="mycat.webm" controls>no fallback coz i is lame, innit.</video>
We could very simply write a script to find all video tags and give them a new src to show our bumper.
<script>
var videos, i, l;
videos = document.getElementsByTagName('video');
for(i=0, l=videos.length; i<l; i++) {
videos[i].setAttribute('src', 'bumper-in.webm');
}
</script>
View the example in a browser with WebM support. You’ll see that the video is swapped out for the opening bumper. Great!
Beefing it up
Of course, we can’t just publish video in one format. In practical use, you need a <video> element with multiple <source> elements containing your different source formats.
<video controls>
<source src="mycat.mp4" type="video/mp4" />
<source src="mycat.webm" type="video/webm" />
<source src="mycat.ogv" type="video/ogg" />
</video>
This time, our script needs to loop through the sources, not the videos. We’ll use a regular expression replacement to swap out the file name while maintaining the correct file extension.
<script>
var sources, i, l, orig;
sources = document.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('src');
sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));
// reload the video
sources[i].parentNode.load();
}
</script>
The difference this time is that when changing the src of a <source> we need to call the .load() method on the video to get it to acknowledge the change.
See the code in action, this time in a wider range of browsers.
But, my video!
I guess we should get the original video playing again. Keeping the same markup, we need to modify the script to do two things:
Store the original src in a data- attribute so we can access it later
Add an event listener so we can detect the end of the bumper playing, and load the original video back in
As we need to loop through the videos this time to add the event listener, I’ve moved the .load() call into that loop. It’s a bit more efficient to call it only once after modifying all the video’s sources.
<script>
var videos, sources, i, l, orig;
sources = document.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('src');
sources[i].setAttribute('data-orig', orig);
sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));
}
videos = document.getElementsByTagName('video');
for(i=0, l=videos.length; i<l; i++) {
videos[i].load();
videos[i].addEventListener('ended', function(){
sources = this.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('data-orig');
if (orig) {
sources[i].setAttribute('src', orig);
}
sources[i].setAttribute('data-orig','');
}
this.load();
this.play();
});
}
</script>
Again, view the example to see the bumper play, followed by our spectacular main feature. (That’s my cat, Widget. His interests include sleeping and internet marketing.)
Tidying things up
The final thing to do is add our closing bumper after the main video has played. This involves the following changes:
We need to keep track of whether the src has been changed, so we only play the video if it’s changed. I’ve added the modified variable to track this, and it stops us getting into a situation where the video just loops forever.
Add an else to the event listener, for when the orig is false (so the main feature has been playing) to load in the end bumper. We also check that we’re not already playing the end bumper. Because looping.
<script>
var videos, sources, i, l, orig, current, modified;
sources = document.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('src');
sources[i].setAttribute('data-orig', orig);
sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));
}
videos = document.getElementsByTagName('video');
for(i=0, l=videos.length; i<l; i++) {
videos[i].load();
modified = false;
videos[i].addEventListener('ended', function(){
sources = this.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('data-orig');
if (orig) {
sources[i].setAttribute('src', orig);
modified = true;
}else{
current = sources[i].getAttribute('src');
if (current.indexOf('bumper-out')==-1) {
sources[i].setAttribute('src', current.replace(/([w]+).(w+)/, 'bumper-out.$2'));
modified = true;
}else{
this.pause();
modified = false;
}
}
sources[i].setAttribute('data-orig','');
}
if (modified) {
this.load();
this.play();
}
});
}
</script>
Yo ho ho, that’s a lot of JavaScript. See it in action – you should get a bumper, the cat video, and an end bumper.
Of course, this code works fine for demonstrating the principle, but it’s very procedural. Nothing wrong with that, but to do something similar in production, you’d probably want to make the code more modular to ease maintainability. Besides, you may want to use a framework, rather than basic JavaScript.
The end credits
One really important principle here is that of progressive enhancement. If the browser doesn’t support JavaScript, the user won’t see your bumper, but they will get the main video. If the browser supports JavaScript but doesn’t allow you to modify the src (as was the case with older versions of iOS), the user won’t see your bumper, but they will get the main video.
If a search engine or social media bot grabs your page and looks for content, they won’t see your bumper, but they will get the main video – which is absolutely what you want.
This means that if the bumper is absolutely crucial, you may still need to cook it into the video. However, for many applications, running it dynamically can work quite well.
As always, it comes down to three things:
Measure your audience: know how people access your site
Test the solution: make sure it works for your audience
Plan for failure: it’s the web and that’s how things work ‘round these parts
But most of all play around with it, have fun and build something awesome. |
2012 |
Drew McLellan |
drewmclellan |
2012-12-01T00:00:00+00:00 |
https://24ways.org/2012/html5-video-bumpers/ |
code |
| 177 |
HTML5: Tool of Satan, or Yule of Santa? |
It would lead to unseasonal arguments to discuss the title of this piece here, and the arguments are as indigestible as the fourth turkey curry of the season, so we’ll restrict our article to the practical rather than the philosophical: what HTML5 can you reasonably expect to be able to use reliably cross-browser in the early months of 2010?
The answer is that you can use more than you might think, due to the seasonal tinsel of feature-detection and using the sparkly pixie-dust of IE-only VML (but used in a way that won’t damage your Elf).
Canvas
canvas is a 2D drawing API that defines a blank area of the screen of arbitrary size, and allows you to draw on it using JavaScript. The pictures can be animated, such as in this canvas mashup of Wolfenstein 3D and Flickr. (The difference between canvas and SVG is that SVG uses vector graphics, so is infinitely scalable. It also keeps a DOM, whereas canvas is just pixels so you have to do all your own book-keeping yourself in JavaScript if you want to know where aliens are on screen, or do collision detection.)
Previously, you needed to do this using Adobe Flash or Java applets, requiring plugins and potentially compromising keyboard accessibility. Canvas drawing is supported now in Opera, Safari, Chrome and Firefox. The reindeer in the corner is, of course, Internet Explorer, which currently has zero support for canvas (or SVG, come to that).
Now, don’t pull a face like all you’ve found in your Yuletide stocking is a mouldy satsuma and a couple of nuts—that’s not the end of the story. Canvas was originally an Apple proprietary technology, and Internet Explorer had a similar one called Vector Markup Language which was submitted to the W3C for standardisation in 1998 but which, unlike canvas, was not blessed with retrospective standardisation.
What you need, then, is some way for Internet Explorer to translate canvas to VML on-the-fly, while leaving the other, more standards-compliant browsers to use the HTML5. And such a way exists—it’s a JavaScript library called excanvas. It’s downloadable from http://code.google.com/p/explorercanvas/ and it’s simple to include it via a conditional comment in the head for IE:
<!--[if IE]>
<script src="excanvas.js"></script>
<![endif]-->
Simply include this, and your canvas will be natively supported in the modern browsers (and the library won’t even be downloaded) whereas IE will suddenly render your canvas using its own VML engine. Be sure, however, to check it carefully, as the IE JavaScript engine isn’t so fast and you’ll need to be sure that performance isn’t too degraded to use.
Forms
Since the beginning of the Web, developers have been coding forms, and then writing JavaScript to check whether an input is a correctly formed email address, URL, credit card number or conforms to some other pattern. The cumulative labour of the world’s developers over the last 15 years makes whizzing round in a sleigh and delivering presents seem like popping to the corner shop in comparison.
With HTML5, that’s all about to change. As Yaili began to explore on Day 3, a host of new attributes to the input element provide built-in validation for email address formats (input type=email), URLs (input type=url), any pattern that can be expressed with a JavaScript-syntax regex (pattern="[0-9][A-Z]{3}") and the like. New attributes such as required, autofocus, input type=number min=3 max=50 remove much of the tedious JavaScript from form validation.
Other, really exciting input types are available (see all input types). The datalist is reminiscent of a select box, but allows the user to enter their own text if they don’t want to choose one of the pre-defined options. input type=range is rendered as a slider, while input type=date pops up a date picker, all natively in the browser with no JavaScript required at all.
Currently, support is most complete in an experimental implementation in Opera and a number of the new attributes in Webkit-based browsers. But don’t let that stop you! The clever thing about the specification of the new Web Forms is that all the new input types are attributes (rather than elements). input defaults to input type=text, so if a browser doesn’t understand a new HTML5 type, it gracefully degrades to a plain text input.
So where does that leave validation in those browsers that don’t support Web Forms? The answer is that you don’t retire your pre-existing JavaScript validation just yet, but you leave it as a fallback after doing some feature detection. To detect whether (say) input type=email is supported, you make a new input type=email with JavaScript but don’t add it to the page. Then, you interrogate your new element to find out what its type attribute is. If it’s reported back as “email”, then the browser supports the new feature, so let it do its work and don’t bring in any JavaScript validation. If it’s reported back as “text”, it’s fallen back to the default, indicating that it’s not supported, so your code should branch to your old validation routines. Alternatively, use the small (7K) Modernizr library which will do this work for you and give you JavaScript booleans like Modernizr.inputtypes[email] set to true or false.
So what does this buy you? Well, first and foremost, you’re future-proofing your code for that time when all browsers support these hugely useful additions to forms. Secondly, you buy a usability and accessibility win. Although it’s tempting to style the stuffing out of your form fields (which can, incidentally, lead to madness), whatever your branding people say, it’s better to leave forms as close to the browser defaults as possible. A browser’s slider and date pickers will be the same across different sites, making it much more comprehensible to users. And, by using native controls rather than faking sliders and date pickers with JavaScript, your forms are much more likely to be accessible to users of assistive technology.
HTML5 DOCTYPE
You can use the new DOCTYPE !doctype html now and – hey presto – you’re writing HTML5, as it’s pretty much a superset of HTML4. There are some useful advantages to doing this. The first is that the HTML5 validator (I use http://html5.validator.nu) also validates ARIA information, whereas the HTML4 validator doesn’t, as ARIA is a new spec developed after HTML4. (Actually, it’s more accurate to say that it doesn’t validate your ARIA attributes, but it doesn’t automatically report them as an error.)
Another advantage is that HTML5 allows tabindex as a global attribute (that is, on any element). Although originally designed as an accessibility bolt-on, I ordinarily advise you don’t use it; a well-structured page should provide a logical tab order through links and form fields already.
However, tabindex="-1" is a legal value in HTML5 as it allows for the element to be programmatically focussable by JavaScript. It’s also very useful for correcting a bug in Internet Explorer when used with a keyboard; in-page links go nowhere if the destination doesn’t have a proprietary property called hasLayout set or a tabindex of -1.
So, whether it is the tool of Satan or yule of Santa, HTML5 is just around the corner. Some you can use now, and by the end of 2010 I predict you’ll be able to use a whole lot more as new browser versions are released. |
2009 |
Bruce Lawson |
brucelawson |
2009-12-05T00:00:00+00:00 |
https://24ways.org/2009/html5-tool-of-satan-or-yule-of-santa/ |
code |
| 309 |
HTTP/2 Server Push and Service Workers: The Perfect Partnership |
Being a web developer today is exciting! The web has come a long way since its early days and there are so many great technologies that enable us to build faster, better experiences for our users. One of these technologies is HTTP/2 which has a killer feature known as HTTP/2 Server Push.
During this year’s Chrome Developer Summit, I watched a really informative talk by Sam Saccone, a Software Engineer on the Google Chrome team. He gave a talk entitled Planning for Performance, and one of the topics that he covered immediately piqued my interest; the idea that HTTP/2 Server Push and Service Workers were the perfect web performance combination.
If you’ve never heard of HTTP/2 Server Push before, fear not - it’s not as scary as it sounds. HTTP/2 Server Push simply allows the server to send data to the browser without having to wait for the browser to explicitly request it first. In this article, I am going to run through the basics of HTTP/2 Server Push and show you how, when combined with Service Workers, you can deliver the ultimate in web performance to your users.
What is HTTP/2 Server Push?
When a user navigates to a URL, a browser will make an HTTP request for the underlying web page. The browser will then scan the contents of the HTML document for any assets that it may need to retrieve such as CSS, JavaScript or images. Once it finds any assets that it needs, it will then make multiple HTTP requests for each resource that it needs and begin downloading one by one. While this approach works well, the problem is that each HTTP request means more round trips to the server before any data arrives at the browser. These extra round trips take time and can make your web pages load slower.
Before we go any further, let’s see what this might look like when your browser makes a request for a web page. If you were to view this in the developer tools of your browser, it might look a little something like this:
As you can see from the image above, once the HTML file has been downloaded and parsed, the browser then makes HTTP requests for any assets that it needs.
This is where HTTP/2 Server Push comes in. The idea behind HTTP/2 Server Push is that when the browser requests a web page from the server, the server already knows about all the assets that are needed for the web page and “pushes” it to browser. This happens when the first HTTP request for the web page takes place and it eliminates an extra round trip, making your site faster.
Using the same example above, let’s “push” the JavaScript and CSS files instead of waiting for the browser to request them. The image below gives you an idea of what this might look like.
Whoa, that looks different - let’s break it down a little. Firstly, you can see that the JavaScript and CSS files appear earlier in the waterfall chart. You might also notice that the loading times for the files are extremely quick. The browser doesn’t need to make an extra HTTP request to the server, instead it receives the critical files it needs all at once. Much better!
There are a number of different approaches when it comes to implementing HTTP/2 Server Push. Adoption is growing and many commercial CDNs such as Akamai and Cloudflare already offer support for Server Push. You can even roll your own implementation depending on your environment. I’ve also previously blogged about building a basic HTTP/2 Server Push example using Node.js. In this post, I’m not going to dive into how to implement HTTP/2 Server Push as that is an entire post in itself! However, I do recommend reading this article to find out more about the inner workings.
HTTP/2 Server Push is awesome, but it isn’t a magic bullet. It is fantastic for improving the load time of a web page when it first loads for a user, but it isn’t that great when they request the same web page again. The reason for this is that HTTP/2 Server Push is not cache “aware”. This means that the server isn’t aware about the state of your client. If you’ve visited a web page before, the server isn’t aware of this and will push the resource again anyway, regardless of whether or not you need it. HTTP/2 Server Push effectively tells the browser that it knows better and that the browser should receive the resources whether it needs them or not. In theory browsers can cancel HTTP/2 Server Push requests if they’re already got something in cache but unfortunately no browsers currently support it. The other issue is that the server will have already started to send some of the resource to the browser by the time the cancellation occurs.
HTTP/2 Server Push & Service Workers
So where do Service Workers fit in? Believe it or not, when combined together HTTP/2 Server Push and Service Workers can be the perfect web performance partnership. If you’ve not heard of Service Workers before, they are worker scripts that run in the background of your website. Simply put, they act as middleman between the client and the browser and enable you to intercept any network requests that come and go from the browser. They are packed with useful features such as caching, push notifications, and background sync. Best of all, they are written in JavaScript, making it easy for web developers to understand.
Using Service Workers, you can easily cache assets on a user’s device. This means when a browser makes an HTTP request for an asset, the Service Worker is able to intercept the request and first check if the asset already exists in cache on the users device. If it does, then it can simply return and serve them directly from the device instead of ever hitting the server.
Let’s stop for a second and analyse what that means. Using HTTP/2 Server Push, you are able to push critical assets to the browser before the browser requests them. Then, using Service Workers you are able to cache these resources so that the browser never needs to make a request to the server again. That means a super fast first load and an even faster second load!
Let’s put this into action. The following HTML code is a basic web page that retrieves a few images and two JavaScript files.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>HTTP2 Push Demo</title>
</head>
<body>
<h1>HTTP2 Push</h1>
<img src="./images/beer-1.png" width="200" height="200" />
<img src="./images/beer-2.png" width="200" height="200" />
<br>
<br>
<img src="./images/beer-3.png" width="200" height="200" />
<img src="./images/beer-4.png" width="200" height="200" />
<!-- Scripts -->
<script async src="./js/promise.min.js"></script>
<script async src="./js/fetch.js"></script>
<script>
// Register the service worker
if ('serviceWorker' in navigator) {
navigator.serviceWorker.register('./service-worker.js').then(function(registration) {
// Registration was successful
console.log('ServiceWorker registration successful with scope: ', registration.scope);
}).catch(function(err) {
// registration failed :(
console.log('ServiceWorker registration failed: ', err);
});
}
</script>
</body>
</html>
In the HTML code above, I am registering a Service Worker file named service-worker.js. In order to start caching assets, I am going to use the Service Worker toolbox . It is a lightweight helper library to help you get started creating your own Service Workers. Using this library, we can actually cache the base web page with the path /push.
The Service Worker Toolbox comes with a built-in routing system which is based on the same routing as Express. With just a few lines of code, you can start building powerful caching patterns.
I’ve add the following code to the service-worker.js file.
(global => {
'use strict';
// Load the sw-toolbox library.
importScripts('/js/sw-toolbox/sw-toolbox.js');
// The route for any requests
toolbox.router.get('/push', global.toolbox.fastest);
toolbox.router.get('/images/(.*)', global.toolbox.fastest);
toolbox.router.get('/js/(.*)', global.toolbox.fastest);
// Ensure that our service worker takes control of the page as soon as possible.
global.addEventListener('install', event => event.waitUntil(global.skipWaiting()));
global.addEventListener('activate', event => event.waitUntil(global.clients.claim()));
})(self);
Let’s break this code down further. Around line 4, I am importing the Service Worker toolbox. Next, I am specifying a route that will listen to any requests that match the URL /push. Because I am also interested in caching the images and JavaScript for that page, I’ve told the toolbox to listen to these routes too.
The best thing about the code above is that if any of the assets exist in cache, we will instantly return the cached version instead of waiting for it to download. If the asset doesn’t exist in cache, the code above will add it into cache so that we can retrieve it when it’s needed again.
You may also notice the code global.toolbox.fastest - this is important because gives you the compromise of fulfilling from the cache immediately, while firing off an additional HTTP request updating the cache for the next visit.
But what does this mean when combined with HTTP/2 Server Push? Well, it means that on the first load of the web page, you are able to “push” everything to the user at once before the browser has even requested it. The Service Worker activates and starts caching the assets on the users device. The next time a user visits the page, the Service Worker will intercept the request and serve the asset directly from cache. Amazing!
Using this technique, the waterfall chart for a repeat visit should look like the image below.
If you look closely at the image above, you’ll notice that the web page returns almost instantly without ever making an HTTP request over the network. Using the Service Worker library, we cached the base page for the route /push, which allowed us to retrieve this directly from cache.
Whether used on their own or combined together, the best thing about these two features is that they are the perfect progressive enhancement. If your user’s browser doesn’t support them, they will simply fall back to HTTP/1.1 without Service Workers. Your users may not experience as fast a load time as they would with these two techniques, but it would be no different from their normal experience. HTTP/2 Server Push and Service Workers are really the perfect partners when it comes to web performance.
Summary
When used correctly, HTTP/2 Server Push and Service Workers can have a positive impact on your site’s load times. Together they mean super fast first load times and even faster repeat views to a web page. Whilst this technique is really effective, it’s worth noting that HTTP/2 push is not a magic bullet. Think about the situations where it might make sense to use it and don’t just simply “push” everything; it could actually lead to having slower page load times. If you’d like to learn more about the rules of thumb for HTTP/2 Server Push, I recommend reading this article for more information.
All of the code in this example is available on my Github repo - if you have any questions, please submit an issue and I’ll get back to you as soon as possible.
If you’d like to learn more about this technique and others relating to HTTP/2, I highly recommend watching Sam Saccone’s talk at this years Chrome Developer Summit.
I’d also like to say a massive thank you to Robin Osborne, Andy Davies and Jeffrey Posnick for helping me review this article before putting it live! |
2016 |
Dean Hume |
deanhume |
2016-12-15T00:00:00+00:00 |
https://24ways.org/2016/http2-server-push-and-service-workers/ |
code |
| 316 |
Have Your DOM and Script It Too |
When working with the XMLHttpRequest object it appears you can only go one of three ways:
You can stay true to the colorful moniker du jour and stick strictly to the responseXML property
You can play with proprietary – yet widely supported – fire and inject the value of responseText property into the innerHTML of an element of your choosing
Or you can be eval() and parse JSON or arbitrary JavaScript delivered via responseText
But did you know that there’s a fourth option giving you the best of the latter two worlds? Mint uses this unmentioned approach to grab fresh HTML and run arbitrary JavaScript simultaneously. Without relying on eval(). “But wait-”, you might say, “when would I need to do this?” Besides the example below this technique is handy for things like tab groups that need initialization onload but miss the main onload event handler by a mile thanks to asynchronous scripting.
Consider the problem
Originally Mint used option 2 to refresh or load new tabs into individual Pepper panes without requiring a full roundtrip to the server. This was all well and good until I introduced the new Client Mode which when enabled allows anyone to view a Mint installation without being logged in. If voyeurs are afoot as Client Mode is disabled, the next time they refresh a pane the entire login page is inserted into the current document. That’s not very helpful so I needed a way to redirect the current document to the login page.
Enter the solution
Wouldn’t it be cool if browsers interpreted the contents of script tags crammed into innerHTML? Sure, but unfortunately, that just wasn’t meant to be. However like the body element, image elements have an onload event handler. When the image has fully loaded the handler runs the code applied to it. See where I’m going with this?
By tacking a tiny image (think single pixel, transparent spacer gif – shudder) onto the end of the HTML returned by our Ajax call, we can smuggle our arbitrary JavaScript into the existing document. The image is added to the DOM, and our stowaway can go to town.
<p>This is the results of our Ajax call.</p>
<img src="../images/loaded.gif" alt="" onload="alert('Now that I have your attention...');" />
Please be neat
So we’ve just jammed some meaningless cruft into our DOM. If our script does anything with images this addition could have some unexpected side effects. (Remember The Fly?) So in order to save that poor, unsuspecting element whose innerHTML we just swapped out from sharing Jeff Goldblum’s terrible fate we should tidy up after ourselves. And by using the removeChild method we do just that.
<p>This is the results of our Ajax call.</p>
<img src="../images/loaded.gif" alt=""
onload="alert('Now that I have your attention...');this.parentNode.removeChild(this);" /> |
2005 |
Shaun Inman |
shauninman |
2005-12-24T00:00:00+00:00 |
https://24ways.org/2005/have-your-dom-and-script-it-too/ |
code |
| 179 |
Have a Field Day with HTML5 Forms |
Forms are usually seen as that obnoxious thing we have to markup and style. I respectfully disagree: forms (on a par with tables) are the most exciting thing we have to work with.
Here we’re going to take a look at how to style a beautiful HTML5 form using some advanced CSS and latest CSS3 techniques. I promise you will want to style your own forms after you’ve read this article.
Here’s what we’ll be creating:
The form. (Icons from Chalkwork Payments)
Meaningful markup
We’re going to style a simple payment form. There are three main sections on this form:
The person’s details
The address details
The credit card details
We are also going to use some of HTML5’s new input types and attributes to create more meaningful fields and use less unnecessary classes and ids:
email, for the email field
tel, for the telephone field
number, for the credit card number and security code
required, for required fields
placeholder, for the hints within some of the fields
autofocus, to put focus on the first input field when the page loads
There are a million more new input types and form attributes on HTML5, and you should definitely take a look at what’s new on the W3C website. Hopefully this will give you a good idea of how much more fun form markup can be.
A good foundation
Each section of the form will be contained within its own fieldset. In the case of the radio buttons for choosing the card type, we will enclose those options in another nested fieldset.
We will also be using an ordered list to group each label / input pair. This will provide us with a (kind of) semantic styling hook and it will also make the form easier to read when viewing with no CSS applied:
The unstyled form
So here’s the markup we are going to be working with:
<form id=payment>
<fieldset>
<legend>Your details</legend>
<ol>
<li>
<label for=name>Name</label>
<input id=name name=name type=text placeholder="First and last name" required autofocus>
</li>
<li>
<label for=email>Email</label>
<input id=email name=email type=email placeholder="example@domain.com" required>
</li>
<li>
<label for=phone>Phone</label>
<input id=phone name=phone type=tel placeholder="Eg. +447500000000" required>
</li>
</ol>
</fieldset>
<fieldset>
<legend>Delivery address</legend>
<ol>
<li>
<label for=address>Address</label>
<textarea id=address name=address rows=5 required></textarea>
</li>
<li>
<label for=postcode>Post code</label>
<input id=postcode name=postcode type=text required>
</li>
<li>
<label for=country>Country</label>
<input id=country name=country type=text required>
</li>
</ol>
</fieldset>
<fieldset>
<legend>Card details</legend>
<ol>
<li>
<fieldset>
<legend>Card type</legend>
<ol>
<li>
<input id=visa name=cardtype type=radio>
<label for=visa>VISA</label>
</li>
<li>
<input id=amex name=cardtype type=radio>
<label for=amex>AmEx</label>
</li>
<li>
<input id=mastercard name=cardtype type=radio>
<label for=mastercard>Mastercard</label>
</li>
</ol>
</fieldset>
</li>
<li>
<label for=cardnumber>Card number</label>
<input id=cardnumber name=cardnumber type=number required>
</li>
<li>
<label for=secure>Security code</label>
<input id=secure name=secure type=number required>
</li>
<li>
<label for=namecard>Name on card</label>
<input id=namecard name=namecard type=text placeholder="Exact name as on the card" required>
</li>
</ol>
</fieldset>
<fieldset>
<button type=submit>Buy it!</button>
</fieldset>
</form>
Making things look nice
First things first, so let’s start by adding some defaults to our form by resetting the margins and paddings of the elements and adding a default font to the page:
html, body, h1, form, fieldset, legend, ol, li {
margin: 0;
padding: 0;
}
body {
background: #ffffff;
color: #111111;
font-family: Georgia, "Times New Roman", Times, serif;
padding: 20px;
}
Next we are going to style the form element that is wrapping our fields:
form#payment {
background: #9cbc2c;
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
border-radius: 5px;
padding: 20px;
width: 400px;
}
We will also remove the border from the fieldset and apply some bottom margin to it. Using the :last-of-type pseudo-class, we remove the bottom margin of the last fieldset — there is no need for it:
form#payment fieldset {
border: none;
margin-bottom: 10px;
}
form#payment fieldset:last-of-type {
margin-bottom: 0;
}
Next we’ll make the legends big and bold, and we will also apply a light-green text-shadow, to add that little extra special detail:
form#payment legend {
color: #384313;
font-size: 16px;
font-weight: bold;
padding-bottom: 10px;
text-shadow: 0 1px 1px #c0d576;
}
Our legends are looking great, but how about adding a clear indication of how many steps our form has? Instead of adding that manually to every legend, we can use automatically generated counters.
To add a counter to an element, we have to use either the :before or :after pseudo-elements to add content via CSS. We will follow these steps:
create a counter using the counter-reset property on the form element
call the counter with the content property (using the same name we’ve created before)
with the counter-incremet property, indicate that for each element that matches our selector, that counter will be increased by 1
form#payment > fieldset > legend:before {
content: "Step " counter(fieldsets) ": ";
counter-increment: fieldsets;
}
Finally, we need to change the style of the legend that is part of the radio buttons group, to make it look like a label:
form#payment fieldset fieldset legend {
color: #111111;
font-size: 13px;
font-weight: normal;
padding-bottom: 0;
}
Styling the lists
For our list elements, we’ll just add some nice rounded corners and semi-transparent border and background. Because we are using RGBa colors, we should provide a fallback for browsers that don’t support them (that comes before the RBGa color). For the nested lists, we will remove these properties because they would be overlapping:
form#payment ol li {
background: #b9cf6a;
background: rgba(255,255,255,.3);
border-color: #e3ebc3;
border-color: rgba(255,255,255,.6);
border-style: solid;
border-width: 2px;
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
border-radius: 5px;
line-height: 30px;
list-style: none;
padding: 5px 10px;
margin-bottom: 2px;
}
form#payment ol ol li {
background: none;
border: none;
float: left;
}
Form controls
Now we only need to style our labels, inputs and the button element.
All our labels will look the same, with the exception of the one for the radio elements. We will float them to the left and give them a width.
For the credit card type labels, we will add an icon as the background, and override some of the properties that aren’t necessary. We will be using the attribute selector to specify the background image for each label — in this case, we use the for attribute of each label.
To add an extra user-friendly detail, we’ll add a cursor: pointer to the radio button labels on the :hover state, so the user knows that he can simply click them to select that option.
form#payment label {
float: left;
font-size: 13px;
width: 110px;
}
form#payment fieldset fieldset label {
background:none no-repeat left 50%;
line-height: 20px;
padding: 0 0 0 30px;
width: auto;
}
form#payment label[for=visa] {
background-image: url(visa.gif);
}
form#payment label[for=amex] {
background-image: url(amex.gif);
}
form#payment label[for=mastercard] {
background-image: url(mastercard.gif);
}
form#payment fieldset fieldset label:hover {
cursor: pointer;
}
Almost there! Now onto the input elements. Here we want to match all inputs, except for the radio ones, and the textarea. For that we will use the negation pseudo-class (:not()). With it we can target all input elements except for the ones with type of radio.
We will also make sure to add some :focus styles and add the appropriate styling for the radio inputs:
form#payment input:not([type=radio]),
form#payment textarea {
background: #ffffff;
border: none;
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
-khtml-border-radius: 3px;
border-radius: 3px;
font: italic 13px Georgia, "Times New Roman", Times, serif;
outline: none;
padding: 5px;
width: 200px;
}
form#payment input:not([type=submit]):focus,
form#payment textarea:focus {
background: #eaeaea;
}
form#payment input[type=radio] {
float: left;
margin-right: 5px;
}
And finally we come to our submit button. To it, we will just add some nice typography and text-shadow, align it to the center of the form and give it some background colors for its different states:
form#payment button {
background: #384313;
border: none;
-moz-border-radius: 20px;
-webkit-border-radius: 20px;
-khtml-border-radius: 20px;
border-radius: 20px;
color: #ffffff;
display: block;
font: 18px Georgia, "Times New Roman", Times, serif;
letter-spacing: 1px;
margin: auto;
padding: 7px 25px;
text-shadow: 0 1px 1px #000000;
text-transform: uppercase;
}
form#payment button:hover {
background: #1e2506;
cursor: pointer;
}
And that’s it! See the completed form.
This form will not look the same on every browser. Internet Explorer and Opera don’t support border-radius (at least not for now); the new input types are rendered as just normal inputs on some browsers; and some of the most advanced CSS, like the counter, :last-of-type or text-shadow are not supported on some browsers. But that doesn’t mean you can’t use them right now, and simplify your development process. My gift to you! |
2009 |
Inayaili de León Persson |
inayailideleon |
2009-12-03T00:00:00+00:00 |
https://24ways.org/2009/have-a-field-day-with-html5-forms/ |
code |
| 121 |
Hide And Seek in The Head |
If you want your JavaScript-enhanced pages to remain accessible and understandable to scripted and noscript users alike, you have to think before you code. Which functionalities are required (ie. should work without JavaScript)? Which ones are merely nice-to-have (ie. can be scripted)? You should only start creating the site when you’ve taken these decisions.
Special HTML elements
Once you have a clear idea of what will work with and without JavaScript, you’ll likely find that you need a few HTML elements for the noscript version only.
Take this example: A form has a nifty bit of Ajax that automatically and silently sends a request once the user enters something in a form field. However, in order to preserve accessibility, the user should also be able to submit the form normally. So the form should have a submit button in noscript browsers, but not when the browser supports sufficient JavaScript.
Since the button is meant for noscript browsers, it must be hard-coded in the HTML:
<input type="submit" value="Submit form" id="noScriptButton" />
When JavaScript is supported, it should be removed:
var checkJS = [check JavaScript support];
window.onload = function () {
if (!checkJS) return;
document.getElementById('noScriptButton').style.display = 'none';
}
Problem: the load event
Although this will likely work fine in your testing environment, it’s not completely correct. What if a user with a modern, JavaScript-capable browser visits your page, but has to wait for a huge graphic to load? The load event fires only after all assets, including images, have been loaded. So this user will first see a submit button, but then all of a sudden it’s removed. That’s potentially confusing.
Fortunately there’s a simple solution: play a bit of hide and seek in the <head>:
var checkJS = [check JavaScript support];
if (checkJS) {
document.write('<style>#noScriptButton{display: none}</style>');
}
First, check if the browser supports enough JavaScript. If it does, document.write an extra <style> element that hides the button.
The difference with the previous technique is that the document.write command is outside any function, and is therefore executed while the JavaScript is being parsed. Thus, the #noScriptButton{display: none} rule is written into the document before the actual HTML is received.
That’s exactly what we want. If the rule is already present at the moment the HTML for the submit button is received and parsed, the button is hidden immediately. Even if the user (and the load event) have to wait for a huge image, the button is already hidden, and both scripted and noscript users see the interface they need, without any potentially confusing flashes of useless content.
In general, if you want to hide content that’s not relevant to scripted users, give the hide command in CSS, and make sure it’s given before the HTML element is loaded and parsed.
Alternative
Some people won’t like to use document.write. They could also add an empty <link /> element to the <head> and give it an href attribute once the browser’s JavaScript capabilities have been evaluated. The <link /> element is made to refer to a style sheet that contains the crucial #noScriptButton{display: none}, and everything works fine.
Important note: The script needs access to the <link />, and the only way to ensure that access is to include the empty <link /> element before your <script> tag. |
2006 |
Peter-Paul Koch |
ppk |
2006-12-06T00:00:00+00:00 |
https://24ways.org/2006/hide-and-seek-in-the-head/ |
code |
| 55 |
How Tabs Should Work |
Tabs in browsers (not browser tabs) are one of the oldest custom UI elements in a browser that I can think of. They’ve been done to death. But, sadly, most of the time I come across them, the tabs have been badly, or rather partially, implemented.
So this post is my definition of how a tabbing system should work, and one approach of implementing that.
But… tabs are easy, right?
I’ve been writing code for tabbing systems in JavaScript for coming up on a decade, and at one point I was pretty proud of how small I could make the JavaScript for the tabbing system:
var tabs = $('.tab').click(function () {
tabs.hide().filter(this.hash).show();
}).map(function () {
return $(this.hash)[0];
});
$('.tab:first').click();
Simple, right? Nearly fits in a tweet (ignoring the whole jQuery library…). Still, it’s riddled with problems that make it a far from perfect solution.
Requirements: what makes the perfect tab?
All content is navigable and available without JavaScript (crawler-compatible and low JS-compatible).
ARIA roles.
The tabs are anchor links that:
are clickable
have block layout
have their href pointing to the id of the panel element
use the correct cursor (i.e. cursor: pointer).
Since tabs are clickable, the user can open in a new tab/window and the page correctly loads with the correct tab open.
Right-clicking (and Shift-clicking) doesn’t cause the tab to be selected.
Native browser Back/Forward button correctly changes the state of the selected tab (think about it working exactly as if there were no JavaScript in place).
The first three points are all to do with the semantics of the markup and how the markup has been styled. I think it’s easy to do a good job by thinking of tabs as links, and not as some part of an application. Links are navigable, and they should work the same way other links on the page work.
The last three points are JavaScript problems. Let’s investigate that.
The shitmus test
Like a litmus test, here’s a couple of quick ways you can tell if a tabbing system is poorly implemented:
Change tab, then use the Back button (or keyboard shortcut) and it breaks
The tab isn’t a link, so you can’t open it in a new tab
These two basic things are, to me, the bare minimum that a tabbing system should have.
Why is this important?
The people who push their so-called native apps on users can’t have more reasons why the web sucks. If something as basic as a tab doesn’t work, obviously there’s more ammo to push a closed native app or platform on your users.
If you’re going to be a web developer, one of your responsibilities is to maintain established interactivity paradigms. This doesn’t mean don’t innovate. But it does mean: stop fucking up my scrolling experience with your poorly executed scroll effects. </rant> :breath:
URI fragment, absolute URL or query string?
A URI fragment (AKA the # hash bit) would be using mysite.com/config#content to show the content panel. A fully addressable URL would be mysite.com/config/content. Using a query string (by way of filtering the page): mysite.com/config?tab=content.
This decision really depends on the context of your tabbing system. For something like GitHub’s tabs to view a pull request, it makes sense that the full URL changes.
For our problem though, I want to solve the issue when the page doesn’t do a full URL update; that is, your regular run-of-the-mill tabbing system.
I used to be from the school of using the hash to show the correct tab, but I’ve recently been exploring whether the query string can be used. The biggest reason is that multiple hashes don’t work, and comma-separated hash fragments don’t make any sense to control multiple tabs (since it doesn’t actually link to anything).
For this article, I’ll keep focused on using a single tabbing system and a hash on the URL to control the tabs.
Markup
I’m going to assume subcontent, so my markup would look like this (yes, this is a cat demo…):
<ul class="tabs">
<li><a class="tab" href="#dizzy">Dizzy</a></li>
<li><a class="tab" href="#ninja">Ninja</a></li>
<li><a class="tab" href="#missy">Missy</a></li>
</ul>
<div id="dizzy">
<!-- panel content -->
</div>
<div id="ninja">
<!-- panel content -->
</div>
<div id="missy">
<!-- panel content -->
</div>
It’s important to note that in the markup the link used for an individual tab references its panel content using the hash, pointing to the id on the panel. This will allow our content to connect up without JavaScript and give us a bunch of features for free, which we’ll see once we’re on to writing the code.
URL-driven tabbing systems
Instead of making the code responsive to the user’s input, we’re going to exclusively use the browser URL and the hashchange event on the window to drive this tabbing system. This way we get Back button support for free.
With that in mind, let’s start building up our code. I’ll assume we have the jQuery library, but I’ve also provided the full code working without a library (vanilla, if you will), but it depends on relatively new (polyfillable) tech like classList and dataset (which generally have IE10 and all other browser support).
Note that I’ll start with the simplest solution, and I’ll refactor the code as I go along, like in places where I keep calling jQuery selectors.
function show(id) {
// remove the selected class from the tabs,
// and add it back to the one the user selected
$('.tab').removeClass('selected').filter(function () {
return (this.hash === id);
}).addClass('selected');
// now hide all the panels, then filter to
// the one we're interested in, and show it
$('.panel').hide().filter(id).show();
}
$(window).on('hashchange', function () {
show(location.hash);
});
// initialise by showing the first panel
show('#dizzy');
This works pretty well for such little code. Notice that we don’t have any click handlers for the user and the Back button works right out of the box.
However, there’s a number of problems we need to fix:
The initialised tab is hard-coded to the first panel, rather than what’s on the URL.
If there’s no hash on the URL, all the panels are hidden (and thus broken).
If you scroll to the bottom of the example, you’ll find a “top” link; clicking that will break our tabbing system.
I’ve purposely made the page long, so that when you click on a tab, you’ll see the page scrolls to the top of the tab. Not a huge deal, but a bit annoying.
From our criteria at the start of this post, we’ve already solved items 4 and 5. Not a terrible start. Let’s solve items 1 through 3 next.
Using the URL to initialise correctly and protect from breakage
Instead of arbitrarily picking the first panel from our collection, the code should read the current location.hash and use that if it’s available.
The problem is: what if the hash on the URL isn’t actually for a tab?
The solution here is that we need to cache a list of known panel IDs. In fact, well-written DOM scripting won’t continuously search the DOM for nodes. That is, when the show function kept calling $('.tab').each(...) it was wasteful. The result of $('.tab') should be cached.
So now the code will collect all the tabs, then find the related panels from those tabs, and we’ll use that list to double the values we give the show function (during initialisation, for instance).
// collect all the tabs
var tabs = $('.tab');
// get an array of the panel ids (from the anchor hash)
var targets = tabs.map(function () {
return this.hash;
}).get();
// use those ids to get a jQuery collection of panels
var panels = $(targets.join(','));
function show(id) {
// if no value was given, let's take the first panel
if (!id) {
id = targets[0];
}
// remove the selected class from the tabs,
// and add it back to the one the user selected
tabs.removeClass('selected').filter(function () {
return (this.hash === id);
}).addClass('selected');
// now hide all the panels, then filter to
// the one we're interested in, and show it
panels.hide().filter(id).show();
}
$(window).on('hashchange', function () {
var hash = location.hash;
if (targets.indexOf(hash) !== -1) {
show(hash);
}
});
// initialise
show(targets.indexOf(location.hash) !== -1 ? location.hash : '');
The core of working out which tab to initialise with is solved in that last line: is there a location.hash? Is it in our list of valid targets (panels)? If so, select that tab.
The second breakage we saw in the original demo was that clicking the “top” link would break our tabs. This was due to the hashchange event firing and the code didn’t validate the hash that was passed. Now this happens, the panels don’t break.
So far we’ve got a tabbing system that:
Works without JavaScript.
Supports right-click and Shift-click (and doesn’t select in these cases).
Loads the correct panel if you start with a hash.
Supports native browser navigation.
Supports the keyboard.
The only annoying problem we have now is that the page jumps when a tab is selected. That’s due to the browser following the default behaviour of an internal link on the page. To solve this, things are going to get a little hairy, but it’s all for a good cause.
Removing the jump to tab
You’d be forgiven for thinking you just need to hook a click handler and return false. It’s what I started with. Only that’s not the solution. If we add the click handler, it breaks all the right-click and Shift-click support.
There may be another way to solve this, but what follows is the way I found – and it works. It’s just a bit… hairy, as I said.
We’re going to strip the id attribute off the target panel when the user tries to navigate to it, and then put it back on once the show code starts to run. This change will mean the browser has nowhere to navigate to for that moment, and won’t jump the page.
The change involves the following:
Add a click handle that removes the id from the target panel, and cache this in a target variable that we’ll use later in hashchange (see point 4).
In the same click handler, set the location.hash to the current link’s hash. This is important because it forces a hashchange event regardless of whether the URL actually changed, which prevents the tabs breaking (try it yourself by removing this line).
For each panel, put a backup copy of the id attribute in a data property (I’ve called it old-id).
When the hashchange event fires, if we have a target value, let’s put the id back on the panel.
These changes result in this final code:
/*global $*/
// a temp value to cache *what* we're about to show
var target = null;
// collect all the tabs
var tabs = $('.tab').on('click', function () {
target = $(this.hash).removeAttr('id');
// if the URL isn't going to change, then hashchange
// event doesn't fire, so we trigger the update manually
if (location.hash === this.hash) {
// but this has to happen after the DOM update has
// completed, so we wrap it in a setTimeout 0
setTimeout(update, 0);
}
});
// get an array of the panel ids (from the anchor hash)
var targets = tabs.map(function () {
return this.hash;
}).get();
// use those ids to get a jQuery collection of panels
var panels = $(targets.join(',')).each(function () {
// keep a copy of what the original el.id was
$(this).data('old-id', this.id);
});
function update() {
if (target) {
target.attr('id', target.data('old-id'));
target = null;
}
var hash = window.location.hash;
if (targets.indexOf(hash) !== -1) {
show(hash);
}
}
function show(id) {
// if no value was given, let's take the first panel
if (!id) {
id = targets[0];
}
// remove the selected class from the tabs,
// and add it back to the one the user selected
tabs.removeClass('selected').filter(function () {
return (this.hash === id);
}).addClass('selected');
// now hide all the panels, then filter to
// the one we're interested in, and show it
panels.hide().filter(id).show();
}
$(window).on('hashchange', update);
// initialise
if (targets.indexOf(window.location.hash) !== -1) {
update();
} else {
show();
}
This version now meets all the criteria I mentioned in my original list, except for the ARIA roles and accessibility. Getting this support is actually very cheap to add.
ARIA roles
This article on ARIA tabs made it very easy to get the tabbing system working as I wanted.
The tasks were simple:
Add aria-role set to tab for the tabs, and tabpanel for the panels.
Set aria-controls on the tabs to point to their related panel (by id).
I use JavaScript to add tabindex=0 to all the tab elements.
When I add the selected class to the tab, I also set aria-selected to true and, inversely, when I remove the selected class I set aria-selected to false.
When I hide the panels I add aria-hidden=true, and when I show the specific panel I set aria-hidden=false.
And that’s it. Very small changes to get full sign-off that the tabbing system is bulletproof and accessible.
Check out the final version (and the non-jQuery version as promised).
In conclusion
There’s a lot of tab implementations out there, but there’s an equal amount that break the browsing paradigm and the simple linkability of content. Clearly there’s a special hell for those tab systems that don’t even use links, but I think it’s clear that even in something that’s relatively simple, it’s the small details that make or break the user experience.
Obviously there are corners I’ve not explored, like when there’s more than one set of tabs on a page, and equally whether you should deliver the initial markup with the correct tab selected. I think the answer lies in using query strings in combination with hashes on the URL, but maybe that’s for another year! |
2015 |
Remy Sharp |
remysharp |
2015-12-22T00:00:00+00:00 |
https://24ways.org/2015/how-tabs-should-work/ |
code |
| 308 |
How to Make a Chrome Extension to Delight (or Troll) Your Friends |
If you’re like me, you grew up drawing mustaches on celebrities. Every photograph was subject to your doodling wrath, and your brilliance was taken to a whole new level with computer programs like Microsoft Paint. The advent of digital cameras meant that no one was safe from your handiwork, especially not your friends. And when you finally got your hands on Photoshop, you spent hours maniacally giggling at your artistic genius.
But today is different. You’re a serious adult with important things to do and a reputation to uphold. You keep up with modern web techniques and trends, and have little time for fun other than a random Giphy on Slack… right?
Nope.
If there’s one thing 2016 has taught me, it’s that we—the self-serious, world-changing tech movers and shakers of the universe—haven’t changed one bit from our younger, more delightable selves.
How do I know? This year I created a Chrome extension called Tabby Cat and watched hundreds of thousands of people ditch productivity for randomly generated cats. Tabby Cat replaces your new tab page with an SVG cat featuring a silly name like “Stinky Dinosaur” or “Tiny Potato”. Over time, the cats collect goodies that vary in absurdity from fishbones to lawn flamingos to Raybans. Kids and adults alike use this extension, and analytics show the majority of use happens Monday through Friday from 9-5. The popularity of Tabby Cat has convinced me there’s still plenty of room in our big, grown-up hearts for fun.
Today, we’re going to combine the formula behind Tabby Cat with your intrinsic desire to delight (or troll) your friends, and create a web app that generates your friends with random objects and environments of your choosing. You can publish it as a Chrome extension to replace your new tab, or simply host it as a website and point to it with the New Tab Redirect extension.
Here’s a sneak peek at my final result featuring my partner, my cat, and I in cheerfully weird accessories. Your result will look however you want it to.
Along the way, we’ll cover how to build a Chrome extension that replaces the new tab page, and explore ways to program randomness into your work to create something truly delightful.
What you’ll need
Adobe Illustrator (or a similar illustration program to export PNG)
Some images of your friends
A text editor
Note: This can be as simple or as complex as you want it to be. Most of the application is pre-built so you can focus on kicking back and getting in touch with your creative side. If you want to dive in deeper, you’ll find ways to do it.
Getting started
Download a local copy of the boilerplate for today’s tutorial here, and open it in a text editor. Inside, you’ll find a simple web app that you can run in Chrome.
Open index.html in Chrome. You should see a grey page that says “Noname”.
Open template.pdf in Adobe Illustrator or a similar program that can export PNG. The file contains an artboard measuring 800px x 800px, with a dotted blue outline of a face. This is your template.
Note: We’re using Google Chrome to build and preview this application because the end-result is a Chrome extension. This means that the application isn’t totally cross-browser compatible, but that’s okay.
Step 1: Gather your friends
The first thing to do is choose who your muses are. Since the holidays are upon us, I’d suggest finding inspiration in your family.
Create your artwork
For each person, find an image where their face is pointed as forward as possible. Place the image onto the Artwork layer of the Illustrator file, and line up their face with the template. Then, rename the artboard something descriptive like face_bob. Here’s my crew:
As you can see, my use of the word “family” extends to cats. There’s no judgement here.
Notice that some of my photos don’t completely fill the artboard–that’s fine. The images will be clipped into ovals when they’re rendered in the application.
Now, export your images by following these steps:
Turn the Template layer off and export the images as PNGs.
In the Export dialog, tick the “Use Artboards” checkbox and enter the range with your faces.
Export at 72ppi to keep things running fast.
Save your images into the images/ folder in your project.
Add your images to config.js
Open scripts/config.js. This is where you configure your extension.
Add key value pairs to the faces object. The key should be the person’s name, and the value should be the filepath to the image.
faces: {
leslie: 'images/face_leslie.png',
kyle: 'images/face_kyle.png',
beep: 'images/face_beep.png'
}
The application will choose one of these options at random each time you open a new tab. This pattern is used for everything in the config file. You give the application groups of choices, and it chooses one at random each time it loads. The only thing that’s special about the faces object is that person’s name will also be displayed when their face is chosen.
Now, when you refresh the project in Chrome, you should see one of your friends along with their name, like this:
Congrats, you’re off and running!
Step 2: Add adjectives
Now that you’ve loaded your friends into the application, it’s time to call them names. This step definitely yields the most laughs for the least amount of effort.
Add a list of adjectives into the prefixes array in config.js. To get the words flowing, I took inspiration from ways I might describe some of my relatives during a holiday gathering…
prefixes: [
'Loving',
'Drunk',
'Chatty',
'Merry',
'Creepy',
'Introspective',
'Cheerful',
'Awkward',
'Unrelatable',
'Hungry',
...
]
When you refresh Chrome, you should see one of these words prefixed before your friend’s name. Voila!
Step 3: Choose your color palette
Real talk: I’m bad at choosing color palettes, so I have a trick up my sleeve that I want to share with you. If you’ve been blessed with the gift of color aptitude, skip ahead.
How to choose colors
To create a color palette, I start by going to a Coolors.co, and I hit the spacebar until I find a palette that I like. We need a wide gamut of hues for our palette, so lock down colors you like and keep hitting the spacebar until you find a nice, full range. You can use as many or as few colors as you like.
Copy these colors into your swatches in Adobe Illustrator. They’ll be the base for any illustrations you create later.
Now you need a set of background colors. Here’s my trick to making these consistent with your illustration palette without completely blending in. Use the “Adjust Palette” tool in Coolors to dial up the brightness a few notches, and the saturation down just a tad to remove any neon effect. These will be your background colors.
Add your background colors to config.js
Copy your hex codes into the bgColors array in config.js.
bgColors: [
'#FFDD77',
'#FF8E72',
'#ED5E84',
'#4CE0B3',
'#9893DA',
...
]
Now when you go back to Chrome and refresh the page, you’ll see your new palette!
Step 4: Accessorize
This is the fun part. We’re going to illustrate objects, accessories, lizards—whatever you want—and layer them on top of your friends.
Your objects will be categorized into groups, and one option from each group will be randomly chosen each time you load the page. Think of a group like “hats” or “glasses”. This will allow combinations of accessories to show at once, without showing two of the same type on the same person.
Create a group of accessories
To get started, open up Illustrator and create a new artboard out of the template. Think of a group of objects that you can riff on. I found hats to be a good place to start. If you don’t feel like illustrating, you can use cut-out images instead.
Next, follow the same steps as you did when you exported the faces. Here they are again:
Turn the Template layer off and export the images as PNGs.
In the Export dialog, tick the “Use Artboards” checkbox and enter the range with your hats.
Export at 72ppi to keep things running fast.
Save your images into the images/ folder in your project.
Add your accessories to config.js
In config.js, add a new key to the customProps object that describes the group of accessories that you just created. Its value should be an array of the filepaths to your images. This is my hats array:
customProps: {
hats: [
'images/hat_crown.png',
'images/hat_santa.png',
'images/hat_tophat.png',
'images/hat_antlers.png'
]
}
Refresh Chrome and behold, accessories!
Create as many more accessories as you want
Repeat the steps above to create as many groups of accessories as you want. I went on to make glasses and hairstyles, so my final illustrator file looks like this:
The last step is adding your new groups to the config object. List your groups in the order that you want them to be stacked in the DOM. My final output will be hair, then hats, then glasses:
customProps: {
hair: [
'images/hair_bowl.png',
'images/hair_bob.png'
],
hats: [
'images/hat_crown.png',
'images/hat_santa.png',
'images/hat_tophat.png',
'images/hat_antlers.png'
],
glasses: [
'images/glasses_aviators.png',
'images/glasses_monacle.png'
]
}
And, there you have it! Randomly generated friends with random accessories.
Feel free to go much crazier than I did. I considered adding a whole group of animals in celebration of the new season of Planet Earth, or even adding Sir David Attenborough himself, or doing a bit of role reversal and featuring the animals with little safari hats! But I digress…
Step 5: Publish it
It’s time to put this in your new tabs! You have two options:
Publish it as a Chrome extension in the Chrome Web Store.
Host it as a website and point to it with the New Tab Redirect extension.
Today, we’re going to cover Option #1 because I want to show you how to make the simplest Chrome extension possible. However, I recommend Option #2 if you want to keep your project private. Every Chrome extension that you publish is made publicly available, so unless your friends want their faces published to an extension that anyone can use, I’d suggest sticking to Option #2.
How to make a simple Chrome extension to replace the new tab page
All you need to do to make your project into a Chrome extension is add a manifest.json file to the root of your project with the following contents. There are plenty of other properties that you can add to your manifest file, but these are the only ones that are required for a new tab replacement:
{
"manifest_version": 2,
"name": "Your extension name",
"version": "1.0",
"chrome_url_overrides" : {
"newtab": "index.html"
}
}
To test your extension, you’ll need to run it in Developer Mode. Here’s how to do that:
Go to the Extensions page in Chrome by navigating to chrome://extensions/.
Tick the checkbox in the upper-right corner labelled “Developer Mode”.
Click “Load unpacked extension…” and select this project.
If everything is running smoothly, you should see your project when you open a new tab. If there are any errors, they should appear in a yellow box on the Extensions page.
Voila! Like I said, this is a very light example of a Chrome extension, but Google has tons of great documentation on how to take things further. Check it out and see what inspires you.
Share the love
Now that you know how to make a new tab extension, go forth and create! But wield your power responsibly. New tabs are opened so often that they’ve become a part of everyday life–just consider how many tabs you opened today. Some people prefer to-do lists in their tabs, and others prefer cats.
At the end of the day, let’s make something that makes us happy. Cheers! |
2016 |
Leslie Zacharkow |
lesliezacharkow |
2016-12-08T00:00:00+00:00 |
https://24ways.org/2016/how-to-make-a-chrome-extension/ |
code |
| 327 |
Improving Form Accessibility with DOM Scripting |
The form label element is an incredibly useful little element – it lets you link the form field unquestionably with the descriptive label text that sits alongside or above it. This is a very useful feature for people using screen readers, but there are some problems with this element.
What happens if you have one piece of data that, for various reasons (validation, the way your data is collected/stored etc), needs to be collected using several form elements?
The classic example is date of birth – ideally, you’ll ask for the date of birth once but you may have three inputs, one each for day, month and year, that you also need to provide hints about the format required. The problem is that to be truly accessible you need to label each field. So you end up needing something to say “this is a date of birth”, “this is the day field”, “this is the month field” and “this is the day field”. Seems like overkill, doesn’t it? And it can uglify a form no end.
There are various ways that you can approach it (and I think I’ve seen them all). Some people omit the label and rely on the title attribute to help the user through; others put text in a label but make the text 1 pixel high and merging in to the background so that screen readers can still get that information. The most common method, though, is simply to set the label to not display at all using the CSS display:none property/value pairing (a technique which, for the time being, seems to work on most screen readers). But perhaps we can do more with this?
The technique I am suggesting as another alternative is as follows (here comes the pseudo-code):
Start with a totally valid and accessible form
Ensure that each form input has a label that is linked to its related form control
Apply a class to any label that you don’t want to be visible (for example superfluous)
Then, through the magic of unobtrusive JavaScript/the DOM, manipulate the page as follows once the page has loaded:
Find all the label elements that are marked as superfluous and hide them
Find out what input element each of these label elements is related to
Then apply a hint about formatting required for input (gleaned from the original, now-hidden label text) – add it to the form input as default text
Finally, add in a behaviour that clears or selects the default text (as you choose)
So, here’s the theory put into practice – a date of birth, grouped using a fieldset, and with the behaviours added in using DOM, and here’s the JavaScript that does the heavy lifting.
But why not just use display:none? As demonstrated at Juicy Studio, display:none seems to work quite well for hiding label elements. So why use a sledge hammer to crack a nut? In all honesty, this is something of an experiment, but consider the following:
Using the DOM, you can add extra levels of help, potentially across a whole form – or even range of forms – without necessarily increasing your markup (it goes beyond simply hiding labels)
Screen readers today may identify a label that is set not to display, but they may not in the future – this might provide a way around
By expanding this technique above, it might be possible to visually change the parent container that groups these items – in this case, a fieldset and legend, which are notoriously difficult to style consistently across different browsers – while still retaining the underlying semantic/logical structure
Well, it’s an idea to think about at least. How is it for you? How else might you use DOM scripting to improve the accessiblity or usability of your forms? |
2005 |
Ian Lloyd |
ianlloyd |
2005-12-03T00:00:00+00:00 |
https://24ways.org/2005/improving-form-accessibility-with-dom-scripting/ |
code |
| 169 |
Incite A Riot |
Given its relatively limited scope, HTML can be remarkably expressive. With a bit of lateral thinking, we can mark up content such as tag clouds and progress meters, even when we don’t have explicit HTML elements for those patterns.
Suppose we want to mark up a short conversation:
Alice: I think Eve is watching.
Bob: This isn’t a cryptography tutorial …we’re in the wrong example!
A note in the the HTML 4.01 spec says it’s okay to use a definition list:
Another application of DL, for example, is for marking up dialogues, with each DT naming a speaker, and each DD containing his or her words.
That would give us:
<dl>
<dt>Alice</dt>: <dd>I think Eve is watching.</dd>
<dt>Bob</dt>: <dd>This isn't a cryptography tutorial ...we're in the wrong example!</dd>
</dl>
This usage of a definition list is proof that writing W3C specifications and smoking crack are not mutually exclusive activities. “I think Eve is watching” is not a definition of “Alice.” If you (ab)use a definition list in this way, Norm will hunt you down.
The conversation problem was revisited in HTML5. What if dt and dd didn’t always mean “definition title” and “definition description”? A new element was forged: dialog. Now the the “d” in dt and dd doesn’t stand for “definition”, it stands for “dialog” (or “dialogue” if you can spell):
<dialog>
<dt>Alice</dt>: <dd>I think Eve is watching.</dd>
<dt>Bob</dt>: <dd>This isn't a cryptography tutorial ...we're in the wrong example!</dd>
</dialog>
Problem solved …except that dialog is no longer in the HTML5 spec. Hixie further expanded the meaning of dt and dd so that they could be used inside details (which makes sense—it starts with a “d”) and figure (…um). At the same time as the content model of details and figure were being updated, the completely-unrelated dialog element was dropped.
Back to the drawing board, or in this case, the HTML 4.01 specification. The spec defines the cite element thusly:
Contains a citation or a reference to other sources.
Perfect! There’s even an example showing how this can applied when attributing quotes to people:
As <CITE>Harry S. Truman</CITE> said,
<Q lang="en-us">The buck stops here.</Q>
For longer quotes, the blockquote element might be more appropriate. In a conversation, where the order matters, I think an ordered list would make a good containing element for this pattern:
<ol>
<li><cite>Alice</cite>: <q>I think Eve is watching.</q></li>
<li><cite>Bob</cite>: <q>This isn't a cryptography tutorial ...we're in the wrong example!</q></li>
</ol>
Problem solved …except that the cite element has been redefined in the HTML5 spec:
The cite element represents the title of a work … A person’s name is not the title of a work … and the element must therefore not be used to mark up people’s names.
HTML5 is supposed to be backwards compatible with previous versions of HTML, yet here we have a semantic pattern already defined in HTML 4.01 that is now non-conforming in HTML5. The entire justification for the change boils down to this line of reasoning:
Given that: titles of works are often italicised and
given that: people’s names are not often italicised and
given that: most browsers italicise the contents of the cite element,
therefore: the cite element should not be used to mark up people’s names.
In other words, the default browser styling is now dictating semantic meaning. The tail is wagging the dog.
Not to worry, the HTML5 spec tells us how we can mark up names in conversations without using the cite element:
In some cases, the b element might be appropriate for names
I believe the colloquial response to this is a combination of the letters W, T and F, followed by a question mark.
The non-normative note continues:
In other cases, if an element is really needed, the span element can be used.
This is not a joke. We are seriously being told to use semantically meaningless elements to mark up content that is semantically meaningful.
We don’t have to take it.
Firstly, any conformance checker—that’s the new politically correct term for “validator”—cannot possibly check every instance of the cite element to see if it’s really the title of a work and not the name of a person. So we can disobey the specification without fear of invalidating our documents.
Secondly, Hixie has repeatedly stated that browser makers have a powerful voice in deciding what goes into the HTML5 spec; if a browser maker refuses to implement a feature, then that feature should come out of the spec because otherwise, the spec is fiction. Well, one of the design principles of HTML5 is the Priority of Constituencies:
In case of conflict, consider users over authors over implementors over specifiers over theoretical purity.
That places us—authors—above browser makers. If we resolutely refuse to implement part of the HTML5 spec, then the spec becomes fiction.
Join me in a campaign of civil disobedience against the unnecessarily restrictive, backwards-incompatible change to the cite element. Start using HTML5 but start using it sensibly. Let’s ensure that bad advice remains fictitious.
Tantek has set up a page on the WHATWG wiki to document usage of the cite element for conversations. Please contribute to it. |
2009 |
Jeremy Keith |
jeremykeith |
2009-12-11T00:00:00+00:00 |
https://24ways.org/2009/incite-a-riot/ |
code |
| 255 |
Inclusive Considerations When Restyling Form Controls |
I would like to begin by saying 2018 was the year that we, as developers, visual designers, browser implementers, and inclusive design and experience specialists rallied together and achieved a long-sought goal: We now have the ability to fully style form controls, across all modern browsers, while retaining their ease of declaration, native functionality and accessibility.
I would like to begin by saying all these things. However, they’re not true. I think we spent the year debating about what file extension CSS should be written in, or something. Or was that last year? Maybe I’m thinking of next year.
Returning to reality, styling form controls is more tricky and time consuming these days rather than flat out “hard”. In fact, depending on the length of the styling-leash a particular browser provides, there are controls you can style quite a bit. As for browsers with shorter leashes, there are other options to force their controls closer to the visual design you’re tasked to match.
However, when striving for custom styled controls, one must be careful not to forget about the inherent functionality and accessibility that many provide. People expect and deserve the products and services they use and pay for to work for them. If these services are visually pleasing, but only function for those who fit the handful of personas they’ve been designed for, then we’ve potentially deprived many people the experiences they deserve.
Quick level setting
Getting down to brass tacks, when creating custom styled form controls that should retain their expected semantics and functionality, we have to consider the following:
Many form elements can be styled directly through standard and browser specific selectors, as well as through some clever styling of markup patterns. We should leverage these native options before reinventing any wheels.
It is important to preserve the underlying semantics of interactive controls. We must not unintentionally exclude people who use assistive technologies (ATs) that rely on these semantics.
Make sure you test what you create. There is a lot of underlying complexity to form controls which may not be immediately apparent if they’re judged solely by their visual presentation in a single browser, or with limited AT testing.
Visually resetting and restyling form controls
Over the course of 2018, I worked on a project where I tested and reported on the accessibility impact of styling various form controls. In conducting my research, I reviewed many of the form controls available in HTML, testing to see how malleable they were to direct styling from standardized CSS selectors.
As I expected, controls such as the various text fields could be restyled rather easily. However, other controls like radio buttons and checkboxes, or sub-elements of special text fields like date, search, and number spinners were resistant to standard-based styling. These particular controls and their sub-elements required specific pseudo-elements to reset and allow for restyling of some of their default presentation.
See the Pen form control styling comparisons by Scott (@scottohara) on CodePen.
https://codepen.io/scottohara/pen/gZOrZm/
Over the years, the ability to directly style form controls has been something many people have clamored for. However, one should realize the benefits of being able to restyle some of these controls may involve more effort than originally anticipated.
If you want to restyle a control from the ground up, then you must also recreate any :active, :focus, and :hover states for the control—all those things that were previously taken care of by browsers. Not only that, but anything you restyle should also work with Windows High Contrast mode, styling for dark mode, and other OS-level settings that browser respect without you even realizing.
You ever try playing with the accessibility settings of your display on macOS, or similar Windows setting?
It is also worth mentioning that any browser prefixed pseudo-elements are not standardized CSS selectors. As MDN mentions at the top of their pages documenting these pseudo-elements:
Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
While this may be a deterrent for some, it’s my opinion the risks are often only skin-deep. By which I mean if a non-standard selector does change, the control may look a bit quirky, but likely won’t cease to function. A bug report which requires a CSS selector change can be an easy JIRA ticket to close, after all.
Can’t make it? Fake it.
Internet Explorer 11 (IE11) is still neck-and-neck with other browsers in vying for the number 2 spot in desktop browser share. Due to IE not recognizing vendor-prefixed appearance properties, some essential controls like checkboxes won’t render as intended.
Additionally, some controls like select boxes, file uploads, and sub-elements of date fields (calendar popups) cannot be modified by just relying on styling their HTML selectors alone. This means that unless your company designs and develops with a progressive enhancement, or graceful degradation mindset, you’ll need to take a different approach in styling.
Getting clever with markup and CSS
The following CodePen demonstrates how we can create a custom checkbox markup pattern. By mindfully utilizing CSS sibling selectors and positioning of the native control, we can create custom visual styling while also retaining the functionality and accessibility expectations of a native checkbox.
See the Pen Accessible Styled Native Checkbox by Scott (@scottohara) on CodePen.
https://codepen.io/scottohara/pen/RqEayN/
Customizing checkboxes by visually hiding the input and styling well-placed markup with sibling selectors may seem old hat to some. However, many variations of these patterns do not take into account how their method of visually hiding the checkboxes can create discovery issues for certain screen reader navigation methods. For instance, if someone is using a mobile device and exploring by touch, how will they be able to drag their finger over an input that has been reduced to a single pixel, or positioned off screen?
As we move away from the simplicity of declaring a single HTML element and using clever CSS and markup patterns to create restyled form controls, we increase the need for additional testing to ensure no expected behaviors are lost. In other words, what should work in theory may not work in practice when you introduce the various different ways people may engage with a form control. It’s worth remembering: what might be typical interactions for ourselves may be problematic if not impossible for others.
Limitations to cleverness
Creative coding will allow us to apply more consistent custom styles to some of the more problematic form controls. There will be a varied amount of custom markup, CSS, and sometimes JavaScript that will be needed to preserve the control’s inherent usability and accessibility for each control we take this approach to.
However, this method of restyling still doesn’t solve for the lack of feature parity across different browsers. Nor is it a means to account for controls which don’t have a native HTML element equivalent, such as a switch or multi-thumb range slider? Maybe there’s a control that calls for a visual design or proposed user experience that would require too much fighting with a native control’s behavior to be worth the level of effort to implement. Here’s where we need to take another approach.
Using ARIA when appropriate
Sometimes we have no other option than to roll up our sleeves and start building custom form controls from scratch. Fair warning though: just because we’re not leveraging a native HTML control as our foundation, it doesn’t mean we have carte blanche to throw semantics out the window. Enter Accessible Rich Internet Applications (ARIA).
ARIA is a set of attributes that can modify existing elements, or extend HTML to include roles, properties and states that aren’t native to the language. While divs and spans have no meaningful semantic information for us to leverage, with help from the ARIA specification and ARIA Authoring Practices we can incorporate these elements to help create the UI that we need while still following the first rule of Using ARIA:
If you can use a native HTML element or attribute with the semantics and behavior you require already built in, instead of re-purposing an element and adding an ARIA role, state or property to make it accessible, then do so.
By using these documents as guidelines, and testing our custom controls with people of various abilities, we can do our best to make sure a custom control performs as expected for as many people as possible.
Exceptions to the rule
One example of a control that allows for an exception to the first rule of Using ARIA would be a switch control.
Switches and checkboxes are similar components, in that they have both on/checked and off/unchecked states. However, checkboxes are often expected within the context of forms, or used to filter search queries on e-commerce sites. Switches are typically used to instantly enable or deactivate a particular setting at a component or app-based level, as this is their behavior in the native mobile apps in which they were popularized.
While a switch control could be created by visually restyling a checkbox, this does not automatically mean that the underlying semantics and functionality will match the visual representation of the control. For example, the following CodePen restyles checkboxes to look like a switch control, but the semantics of the checkboxes remain which communicate a different way of interacting with the control than what you might expect from a native switch control.
See the Pen Switch Boxes - custom styled checkboxes posing as switches by Scott (@scottohara) on CodePen.
https://codepen.io/scottohara/pen/XyvoeE/
By adding a role="switch" to these checkboxes, we can repurpose the inherent checked/unchecked states of the native control, it’s inherent ability to be focused by Tab key, and Space key to toggle state.
But while this is a valid approach to take in building a switch, how does this actually match up to reality?
Does it pass the test(s)?
Whether deconstructing form controls to fully restyle them, or leveraging them and other HTML elements as a base to expand on, or create, a non-native form control, building it is just the start. We must test that what we’ve restyled or rebuilt works the way people expect it to, if not better.
What we must do here is run a gamut of comparative tests to document the functionality and usability of native form controls. For example:
Is the control implemented in all supported browsers?
If not: where are the gaps? Will it be necessary to implement a custom solution for the situations that degrade to a standard text field?
If so: is each browser’s implementation a good user experience? Is there room for improvement that can be tested against the native baseline?
Test with multiple input devices.
Where the control is implemented, what is the quality of the user experience when using different input devices, such as mouse, touchscreen, keyboard, speech recognition or switch device, to name a few.
You’ll find some HTML5 controls (like date pickers and number spinners) have additional UI elements that may not be announced to AT, or even allow keyboard accessibility. Often these controls can be adjusted by other means, such as text entry, or using arrow keys to increase or decrease values. If restyling or recreating a custom version of a control like these, it may make sense to maintain these native experiences as well.
How well does the control take to custom styles?
If a control can be styled enough to not need to be rebuilt from scratch, that’s great! But make sure that there are no adverse affects on the accessibility of it. For instance, range sliders can be restyled and maintain their functionality and accessibility. However, elements like progress bars can be negatively affected by direct styling.
Always test with different browser and AT pairings to ensure nothing is lost when controls are restyled.
Do specifications match reality?
If recreating controls to get around native limitations, such as the inability to style the options of a select element, or requiring a Switch control which is not native to HTML, do your solutions match user expectations?
For instance, selects have unique picker interfaces on touch devices. And switches have varied levels of support for different browser and screen reader pairings. Test with real people, and check your analytics. If these experiences don’t match people’s expectations, then maybe another solution is in order?
Wrapping up
While styling form controls is definitely easier than it’s ever been, that doesn’t mean that it’s at all simple, nor will it likely ever be. The level of difficulty you’re going to face is going to depend entirely on what it is you’re hoping to style, add-on to, or recreate. And even if you build your custom control exactly to specification, you’ll still be reliant on browsers and assistive technologies being able to fully understand the component they’ve been presented.
Forms and their controls are an incredibly important part of what we need the Internet for. Paying bills, scheduling appointments, ordering groceries, renewing your license or even ordering gifts for the holidays. These are all important tasks that people should be able to complete with as little effort as possible. Especially since for some, completing these tasks online might be their only option.
2018 didn’t end up being the year we got full customization of form controls sorted out. But that’s OK. If we can continue to mindfully work with what we have, and instead challenge ourselves to follow inclusive design principles, well thought out Form Design Patterns, and solve problems with an accessibility first approach, we may come to realize that we can get along just fine without fully branded drop downs.
And hey. There’s always next year, right? |
2018 |
Scott O'Hara |
scottohara |
2018-12-13T00:00:00+00:00 |
https://24ways.org/2018/inclusive-considerations-when-restyling-form-controls/ |
code |
| 91 |
Infinite Canvas: Moving Beyond the Page |
Remember Web 2.0? I do. In fact, that phrase neatly bifurcates my life on the internet. Pre-2.0, I was occupied by chatting on AOL and eventually by learning HTML so I could build sites on Geocities. Around 2002, however, I saw a WYSIWYG demo in Dreamweaver. The instructor was dragging boxes and images around a canvas. With a few clicks he was able to build a dynamic, single-page interface. Coming from the world of tables and inline HTML styles, I was stunned.
As I entered college the next year, the web was blossoming: broadband, Wi-Fi, mobile (proud PDA owner, right here), CSS, Ajax, Bloglines, Gmail and, soon, Google Maps. I was a technology fanatic and a hobbyist web developer. For me, the web had long been informational. It was now rapidly becoming something else, something more: sophisticated, presentational, actionable.
In 2003 we watched as the internet changed. The predominant theme of those early Web 2.0 years was the withering of Internet Explorer 6 and the triumph of web standards. Upon cresting that mountain, we looked around and collectively breathed the rarefied air of pristine HMTL and CSS, uncontaminated by toxic hacks and forks – only to immediately begin hurtling down the other side at what is, frankly, terrifying speed.
Ten years later, we are still riding that rocket. Our days (and nights) are spent cramming for exams on CSS3 and RWD and Sass and RESS. We are the proud, frazzled owners of tiny pocket computers that annihilate the best laptops we could have imagined, and the architects of websites that are no longer restricted to big screens nor even segregated by device. We dragoon our sites into working any time, anywhere. At this point, we can hardly ask the spec developers to slow down to allow us to catch our breath, nor should we. It is, without a doubt, a most wonderful time to be a web developer.
But despite the newfound luxury of rounded corners, gradients, embeddable fonts, low-level graphics APIs, and, glory be, shadows, the canyon between HTML and native appears to be as wide as ever. The improvements in HTML and CSS have, for the most part, been conveniences rather than fundamental shifts. What I’d like to do now, if you’ll allow me, is outline just a few of the remaining gaps that continue to separate web sites and applications from their native companions.
What I’d like for Christmas
There is one irritant which is the grandfather of them all, the one from which all others flow and have their being, and it is, simply, the page refresh. That’s right, the foundational principle of the web is our single greatest foe. To paraphrase a patron saint of designers everywhere, if you see a page refresh, we blew it.
The page refresh brings with it, of course, many noble and lovely benefits: addressability, for one; and pagination, for another. (See also caching, resource loading, and probably half a dozen others.) Still, those concerns can be answered (and arguably answered more compellingly) by replacing the weary page with the young and hearty document. Flash may be dead, but it has many lessons yet to bequeath.
Preparing a single document when the site loads allows us to engage the visitor in a smooth and engrossing experience. We have long known this, of course. Twitter was not the first to attempt, via JavaScript, to envelop the user in a single-page application, nor the first to abandon it. Our shared task is to move those technologies down the stack, to make them more primitive, so that the next Twitter can be built with the most basic combination of HTML and CSS rather than relying on complicated, slow, and unreliable scripted solutions.
So, let’s take a look at what we can do, right now, that we might have a better idea of where our current tools fall short.
A print magazine in HTML clothing
Like many others, I suspect, one of my earliest experiences with publishing was laying out newsletters and newspapers on a computer for print. If you’ve ever used InDesign or Quark or even Microsoft Publisher, you’ll remember reflowing content from page to page. The advent of the internet signaled, in many ways, the abandonment of that model. Articles were no longer constrained by the physical limitations of paper. In shedding our chains, however, it is arguable that we’ve lost something useful. We had a self-contained and complete package, a closed loop. It was a thing that could be handled and finished, and doing so provided a sense of accomplishment that our modern, infinitely scrolling, ever-fractal web of content has stolen.
For our purposes today, we will treat 24 ways as the online equivalent of that newspaper or magazine. A single year’s worth of articles could easily be considered an issue. Right now, navigating between articles means clicking on the article you’d like to view and being taken to that specific address via a page reload. If Drew wanted to, it wouldn’t be difficult to update the page in place (via JavaScript) and change the address (again via JavaScript with the History API) to reflect the new content found at the new location. But what if Drew wanted to do that without JavaScript? And what if he wanted the site to not merely load the content but actually whisk you along the page in a compelling and delightful way, à la the Mag+ demo we all saw a few years ago when the iPad was first introduced? Uh, no.
We’re all familiar with websites that have attempted to go beyond the page by weaving many chunks of content together into a large document and for good reason. There is tremendous appeal in opening and exploring the canvas beyond the edges of our screens.
In one rather straightforward example from last year, Mozilla contacted Full Stop to build a website promoting Aza Raskin’s proposal for a set of Creative Commons-style privacy icons. Like a lot of the sites we build (including our own), the amount of information we were presenting was minimal. In these instances, we encourage our clients to consider including everything on a single page. The result was a horizontally driven site that was, if not whimsical, at least clever and attractive to the intended audience. An experience that is taken for granted when using device-native technology is utterly, maddeningly impossible to replicate on the web without jumping through JavaScript hoops.
In another, more complex example, we again had the pleasure of working with Aza earlier this year, this time on a redesign of the Massive Health website. Our assignment was to design and build a site that communicated Massive’s commitment to modern personal health. The site had to be visually and interactively stunning while maintaining a usable and clear interface for the casual visitor. Our solution was to extend the infinite company logo into a ribbon that carried the visitor through the site narrative. It also meant we’d be asking the browser to accommodate something it was never designed to handle: a non-linear design. (Be sure to play around. There’s a lot going on under the hood. We were also this close to a ZUI, if WebKit didn’t freak out when pages were scaled beyond 10×.) Despite the apparent and deliberate design simplicity, the techniques necessary to implement it are anything but. From updating the URL to moving the visitor from section to section, we’re firmly in JavaScript territory. And that’s a shame.
What can we do?
We might not be able to specify these layouts in HTML and CSS just yet, but that doesn’t mean we can’t learn a few new tricks while we wait. Let’s see how close we can come to recreating the privacy icons design, the Massive design, or the Mag+ design without resorting to JavaScript.
A horizontally paginated site
The first thing we’re going to need is the concept of a page within our HTML document. Using plain old HTML and CSS, we can stack a series of <div>s sideways (with a little assist from our new friend, the viewport-width unit, not that he was strictly necessary). All we need to know is how many pages we have. (And, boy, wouldn’t it be nice to be able to know that without having to predetermine it or use JavaScript?)
.window {
overflow: hidden;
width: 100%;
}
.pages {
width: 200vw;
}
.page {
float: left;
overflow: hidden;
width: 100vw;
}
If you look carefully, you’ll see that the conceit we’ll use in the rest of the demos is in place. Despite the document containing multiple pages, only one is visible at any given time. This allows us to keep the user focused on the task (or content) at hand.
By the way, you’ll need to use a modern, WebKit-based browser for these demos. I recommend downloading the WebKit nightly builds, Chrome Canary, or being comfortable with setting flags in Chrome.
A horizontally paginated site, with transitions
Ah, here’s the rub. We have functional navigation, but precious few cues for the user. It’s not much good shoving the visitor around various parts of the document if they don’t get the pleasant whooshing experience of the journey. You might be thinking, what about that new CSS selector, target-something…? Well, my friend, you’re on the right track. Let’s test it. We’re going to need to use a bit of sleight of hand. While we’d like to simply offset the containing element by the number of pages we’re moving (like we did on Massive), CSS alone can’t give us that information, and that means we’re going to need to fake it by expanding and collapsing pages as you navigate. Here are the bits we’re going to need:
.page {
-webkit-transition: width 1s; // Naturally you're going to want to include all the relevant prefixes here
float: left;
left: 0;
overflow: hidden;
position: relative;
width: 100vw;
}
.page:not(:target) {
width: 0;
}
Ah, but we’re not fooling anyone with that trick. As soon as you move beyond a single page, the visitor’s disbelief comes tumbling down when the linear page transitions are unaffected by the distance the pages are allegedly traveling. And you may have already noticed an even more fatal flaw: I secretly linked you to the first page rather than the unadorned URL. If you visit the same page with no URL fragment, you get a blank screen. Sure, we could force a redirect with some server-side trickery, but that feels like cheating. Perhaps if we had the CSS4 subject selector we could apply styles to the parent based on the child being targeted by the URL. We might also need a few more abilities, like determining the total number of pages and having relative sibling selectors (e.g. nth-sibling), but we’d sure be a lot closer.
A horizontally paginated site, with transitions – no cheating
Well, what other cards can we play? How about the checkbox hack? Sure, it’s a garish trick, but it might be the best we can do today. Check it out.
label {
cursor: pointer;
}
input {
display: none;
}
input:not(:checked) + .page {
max-height: 100vh;
width: 0;
}
Finally, we can see the first page thanks to the state we are able to set on the appropriate radio button. Of course, now we don’t have URLs, so maybe this isn’t a winning plan after all. While our HTML and CSS toolkit may feel primitive at the moment, we certainly don’t want to sacrifice the addressability of the web. If there’s one bedrock principle, that’s it.
A horizontally paginated site, with transitions – no cheating and a gorgeous homepage
Gorgeous may not be the right word, but our little magazine is finally shaping up. Thanks to the CSS regions spec, we’ve got an exciting new power, the ability to begin an article in one place and bend it to our will. (Remember, your everyday browser isn’t going to work for these demos. Try the WebKit nightly build to see what we’re talking about.) As with the rest of the examples, we’re clearly abusing these features. Off-canvas layouts (you can thank Luke Wroblewski for the name) are simply not considered to be normal patterns… yet.
Here’s a quick look at what’s going on:
.excerpt-container {
float: left;
padding: 2em;
position: relative;
width: 100%;
}
.excerpt {
height: 16em;
}
.excerpt_name_article-1,
.page-1 .article-flow-region {
-webkit-flow-from: article-1;
}
.article-content_for_article-1 {
-webkit-flow-into: article-1;
}
The regions pattern is comprised of at least three components: a beginning; an ending; and a source. Using CSS, we’re able to define specific elements that should be available for the content to flow through. If magazine-style layouts are something you’re interested in learning more about (and you should be), be sure to check out the great work Adobe has been doing.
Looking forward, and backward
As designers, builders, and consumers of the web, we share a desire to see the usability and enjoyability of websites continue to rise. We are incredibly lucky to be working in a time when a three-month-old website can be laughably outdated. Our goal ought to be to improve upon both the weaknesses and the strengths of the web platform. We seek not only smoother transitions and larger canvases, but fine-grained addressability. Our URLs should point directly and unambiguously to specific content elements, be they pages, sections, paragraphs or words. Moreover, off-screen design patterns are essential to accommodating and empowering the multitude of devices we use to access the web. We should express the desire that interpage links take advantage of the CSS transitions which have been put to such good effect in every other aspect of our designs. Transitions aren’t just nice to have, they’re table stakes in the highly competitive world of native applications.
The tools and technologies we have right now allow us to create smart, beautiful, useful webpages. With a little help, we can begin removing the seams and sutures that bind the web to an earlier, less sophisticated generation. |
2012 |
Nathan Peretic |
nathanperetic |
2012-12-21T00:00:00+00:00 |
https://24ways.org/2012/infinite-canvas-moving-beyond-the-page/ |
code |
| 295 |
Internet of Stranger Things |
This year I’ve been running a workshop about using JavaScript and Node.js to work with all different kinds of electronics on the Raspberry Pi. So especially for 24 ways I’m going to show you how I made a very special Raspberry Pi based internet connected project! And nothing says Christmas quite like a set of fairy lights connected to another dimension1.
What you’ll see
You can rig up the fairy lights in your home, with the scrawly letters written under each one. The people from the other side (i.e. the internet) will be able to write messages to you from their browser in real time. In fact why not try it now; check this web page. When you click the lights in your browser, my lights (and yours) will turn on and off in real life! (There may be a queue if there are lots of people accessing it, hit the “Send a message” button and wait your turn.)
It’s all done with JavaScript, using Node.js running on both the Raspberry Pi and on the server. I’m using WebSockets to communicate in real time between the browser, server and Raspberry Pi.
What you’ll need
Raspberry Pi any of the following models: Zero (will need straight male header pins soldered2 and Micro USB OTG adaptor), A+, B+, 2, or 3
Micro SD card at least 4Gb Class 10 speed3
Micro USB power supply at least 2A
USB Wifi dongle (unless you have a Pi 3 - that has wifi built in).
Addressable fairy lights
Logic level shifter (with pins soldered unless you want to do it!)
Breadboard
Jumper wires (3x male to male and 4x female to male)
Optional but recommended
Base board to hold the Pi and Breadboard (often comes with a breadboard!)
Find links for where to buy all of these items that goes along with this tutorial. The total price should be around $1004.
Setting up the Raspberry Pi
You’ll need to install the SD card for the Raspberry Pi. You’ll find a link to download a disk image on the support document, ready-made with the Raspbian version of Linux, along with Node.js and all the files you need. Download it and write it to the SD card using the fantastic free software Etcher5.
Next up you have to configure the wifi details on the SD card. If you plug the card into your computer you should see a drive called BOOT. There’s a text file on there called wpa_supplicant.conf. Open it up in your favourite text editor and replace mywifi and mypassword with your wifi details6.
network={
ssid="mywifi"
psk="mypassword"
}
Save the file, eject the card from your computer and plug it into the Raspberry Pi.
If you have a base board or holder for the Raspberry Pi, attach it now. Then connect the wifi USB dongle7 and power supply, but don’t plug it in yet!
Wiring!
Time to wire everything up!
First of all, push the Logic Level Converter into the middle of the breadboard:
Logic Level Converter
The logic level converter may be labelled differently from the one in the diagram but the pins are usually exactly the same internally. I would just make sure the pins marked HV (High Voltage) are on the bottom and LV (Low Voltage) are on the top.
Raspberry Pi pins only output 3.3v but the lights need 5v. That’s why we need the logic level converter in there to boost up the signal.
Connect the first two wires between the Raspberry Pi pins and the breadboard:
Note that the pins on the Raspberry Pi are male, so you need a female to male jumper wire to connect between them and the breadboard. The colours don’t have to match but it’s easier to follow (and check) if you use the same ones as in the diagram.
Then the next two:
This is what you should have so far:
Lights
Now to connect the lights! My ones have a connector with three holes in it that I can push jumper wires into, and hopefully yours will too! So I used the male-to-male jumper wires to connect them to the breadboard.
Make sure that you connect the right end of the lights, mine has a male connector at the wrong end so it’s impossible to do this, but double check.
Also make sure that the holes in the light connector are the same as mine. To do this, follow the wires from the connector to the first light and look at the circuit board inside. You should just about be able to make out the connections labelled + (sometimes 5V, V+ or VCC), GND (or ‘-’ or G) and DI (sometimes DIN for data in).
You can just about make out the +, DI and GND on this picture. Note that on the other side of the board there is a DO for data out - that’s what takes the data along to the chip in the next light. Make sure that you’re plugging into the data-in and not the data-out!
That’s it! Everything’s plugged in and ready to go! But before you plug power into your Pi, double check all your wires and make sure they’re exactly right! You could damage your Raspberry Pi if it is not wired correctly. So triple check!
The Moment of Truth!
Plug in the Raspberry Pi and wait around a minute or two for it to boot up. If all is well, the lights should strobe rainbow colours for one second - that’s your confirmation that it’s connected to my WebSocket server and ready to receive messages from the upside-down!
However, if the first light in the string is pulsing red, it means that you’re not connected to the internet. So check the Troubleshooting section of the support document. If it’s pulsing green then you’re connected to the internet but can’t connect to my server. It must have gone down. Sorry! The code will keep trying so leave it running and maybe it’ll come back up.
Rig up the lights!
Fix the lights up on the wall however you want, pins, nails, tape. I’ve used cable clips. Just be careful! I’m using a 50 light string so I’ve programmed it to use the lights at the end for the letters. That way I have just under half the string to extend down to the floor where I can keep the Raspberry Pi.
Check the photo here to see how the lights line up, note that there are spare unused lights in-between each row:
Now visit lights.seb.ly and you’ll see this :
If you’re the only one online you’ll have direct connection to the lights and any letter you click on will light up both in the browser and in real life. If there are other people there, you’ll need to click the button to join the queue and wait your turn.
How it works - the geeky details!
Electronics:
The pins on the Raspberry Pi are known as GPIO pins, general-purpose input/output. You can connect a wide variety of electronic components to them, LED lights, buttons, switches, and sensors. You can turn the power to the pins on and off using Node.js (or Python, if you prefer).
Addressable LEDs or “Neopixels”
We’re only using one GPIO pin on the Raspberry Pi (the other connections are 5V, 3.3V and ground) and that single pin is controlling all of the lights in the string. The code turns the pin on and off really fast in strictly timed morse-code-like dots and dashes to transmit binary data. The chips attached to each LED decode the binary and adjust the output to the LED accordingly. That chip then sends the data on to the next light in the string.
The chips on each light are the WS2811, part of the WS281x family that come in a multitude of different form factors and are often packaged with tiny LEDs in a single component. They are commonly referred to as Neopixels8 and I used them on my Laser Light Synths project.
Neopixels with the chip and the LED all in one - it’s the white square shaped component and the darker square inside is the chip. These are only 5mm wide!
A Laser Light Synth! Covered with around 800 super bright neopixels!
Logic Level Converter
The logic level converter is a really cheap and easy way to change the level from 3.3v to 5v and back again. You must be careful that you do not connect 5v into a GPIO pin or you will most likely damage the Raspberry Pi processor chip.
Power
Neopixels can often draw a lot of current so you need to be careful how you power them. I’ve measured the current draw from the string to be less than 800mA so you should be fine wired directly to the 5V output. But if you use more lights or have them all on really bright at once, you’ll need to use a separate 5V power supply. If you want to learn more, check out Adafruit’s Neopixel Uberguide.
Node.js
There are two Node.js apps running here, one on the Raspberry Pi and one on my server. You can see the code on my GitHub at github.com/sebleedelisle/stranger-lights for the Raspberry Pi and github.com/sebleedelisle/stranger-lights-server for the server. And they’re hosted on npm as stranger-lights and stranger-lights-server.
The server side code sets up a standard web server to deliver the HTML for the web interface. It also sets up a WebSocket server that allows for real-time communication between the browser and the server. This server code also manages the queue and who is in control of the lights at any given time.
WebSockets
I’m using the excellent Socket.io library to manage the WebSocket connection. Both the browser and the Raspberry Pi Node.js app connects to my WebSocket server.
When you click on a letter in the browser, a message is sent to the server, which forwards it to the connected Raspberry Pi clients and also all the web browsers9.
The Raspberry Pi code
The Node.js app runs automatically on startup, and I made this happen by adding this to the /etc/rc.local file:
node /home/pi/strangerthings/client.js > /dev/null &
Anything in the rc.local file gets executed when the Pi boots up and this line of code runs the Node.js app and routes its output to nowhere (ie /dev/null). The & means that it runs it in the background and doesn’t hold up the boot process.
Working with the Raspberry Pi headless
You might know that when a computer has no screen or keyboard, you would refer to it as “running headless”. So just like most web servers, you need to configure it over the network with ssh10. If you’re on a mac you can find your Pi on the network through the name raspberrypi.local11, otherwise you’ll need to find its IP address. There’s more on the guide to Remote Access instructions on the Raspberry Pi website. And if you’re very new to the terminal, I highly recommend this great online Linux command line tutorial.
Improvements
This is quite an early experiment and I’m sure I’ll discover lots of optimisations over the next few weeks, especially if the server gets a proper hammering today! But there are a few things you can do. Obviously I’ve just rigged up my lights with Post-it notes. It’d be a lot nicer to get a paint brush and try to recreate the Winona-in-a-manic-state text style.
Where next?
Finding quality resources about Node.js for electronics on the Pi can be somewhat hit and miss, but this is getting better all the time. Alternatively I am thinking about running some online courses, please let me know if that’s something you’d be interested in, or sign up to my mailing list at st4i.com.
There are many many more resources for the Raspberry Pi with Python (gpiozero is a good place to start), so if that language works for you, you’ll be spoilt for choice!
Also take a look at Arduino - it’s an incredibly popular platform for electronics and the internet is literally bursting with resources.
I hope you enjoyed this little foray into the world of JavaScript electronics on the Raspberry Pi! If you get this working at home please let me know! Tweet me at @seb_ly.
Not a particularly original idea, but I don’t think I’ve seen anyone do it quite like this before, ie using WebSockets, and Node.js on a Raspberry Pi. Other examples: Internet of Stranger Things, Strangerlights.com, and loads of examples on Instructables ↩︎
Video guide to soldering pins on to a Pi Zero and further soldering advice from Adafruit ↩︎
Slower cards will work but performance may suffer ↩︎
Or £5,000 in UK money. Sorry, Brexit joke :) ↩︎
You will need a card reader on your computer - most micro SD cards come with an adaptor that fits standard SD slots. ↩︎
SSID and password should be all that you need but you can see all the config options on this wpa supplicant guide ↩︎
Raspberry Pi Zero will require the OTG to USB adaptor to attach the wifi dongle ↩︎
Thanks to Adafruit who invented the term neopixels so we don’t have to refer to them as WS281x any more! ↩︎
So you can see other people sending messages in the browser ↩︎
ssh is short for Secure Shell and is a way to connect to a remote computer and type in it just like you would in the terminal. ↩︎
You can change this default hostname using raspi-config ↩︎ |
2016 |
Seb Lee-Delisle |
sebleedelisle |
2016-12-01T00:00:00+00:00 |
https://24ways.org/2016/internet-of-stranger-things/ |
code |
| 126 |
Intricate Fluid Layouts in Three Easy Steps |
The Year of the Script may have drawn attention away from CSS but building fluid, multi-column, cross-browser CSS layouts can still be as unpleasant as a lump of coal. Read on for a worry-free approach in three quick steps.
The layout system I developed, YUI Grids CSS, has three components. They can be used together as we’ll see, or independently.
The Three Easy Steps
Choose fluid or fixed layout, and choose the width (in percents or pixels) of the page.
Choose the size, orientation, and source-order of the main and secondary blocks of content.
Choose the number of columns and how they distribute (for example 50%-50% or 25%-75%), using stackable and nestable grid structures.
The Setup
There are two prerequisites: We need to normalize the size of an em and opt into the browser rendering engine’s Strict Mode.
Ems are a superior unit of measure for our case because they represent the current font size and grow as the user increases their font size setting. This flexibility—the container growing with the user’s wishes—means larger text doesn’t get crammed into an unresponsive container. We’ll use YUI Fonts CSS to set the base size because it provides consistent-yet-adaptive font-sizes while preserving user control.
The second prerequisite is to opt into Strict Mode (more info on rendering modes) by declaring a Doctype complete with URI. You can choose XHTML or HTML, and Transitional or Strict. I prefer HTML 4.01 Strict, which looks like this:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
Including the CSS
A single small CSS file powers a nearly-infinite number of layouts thanks to a recursive system and the interplay between the three distinct components. You could prune to a particular layout’s specific needs, but why bother when the complete file weighs scarcely 1.8kb uncompressed? Compressed, YUI Fonts and YUI Grids combine for a miniscule 0.9kb over the wire.
You could save an HTTP request by concatenating the two CSS files, or by adding their contents to your own CSS, but I’ll keep them separate for now:
<link href="fonts.css" rel="stylesheet" type="text/css">
<link href="grids.css" rel="stylesheet" type="text/css">
Example: The Setup
Now we’re ready to build some layouts.
Step 1: Choose Fluid or Fixed Layout
Choose between preset widths of 750px, 950px, and 100% by giving a document-wrapping div an ID of doc, doc2, or doc3. These options cover most use cases, but it’s easy to define a custom fixed width.
The fluid 100% grid (doc3) is what I’ve been using almost exclusively since it was introduced in the last YUI released.
<body>
<div id="doc3"></div>
</body>
All pages are centered within the viewport, and grow with font size. The 100% width page (doc3) preserves 10px of breathing room via left and right margins. If you prefer your content flush to the viewport, just add doc3 {margin:auto} to your CSS.
Regardless of what you choose in the other two steps, you can always toggle between these widths and behaviors by simply swapping the ID value. It’s really that simple.
Example: 100% fluid layout
Step 2: Choose a Template Preset
This is perhaps the most frequently omitted step (they’re all optional), but I use it nearly every time. In a source-order-independent way (good for accessibility and SEO), “Template Presets” provide commonly used template widths compatible with ad-unit dimension standards defined by the Interactive Advertising Bureau, an industry association.
Choose between the six Template Presets (.yui-t1 through .yui-t6) by setting the class value on the document-wrapping div established in Step 1. Most frequently I use yui-t3, which puts the narrow secondary block on the left and makes it 300px wide.
<body>
<div id="doc3" class="yui-t3"></div>
</body>
The Template Presets control two “blocks” of content, which are defined by two divs, each with yui-b (“b” for “block”) class values. Template Presets describe the width and orientation of the secondary block; the main block will take up the rest of the space.
<body>
<div id="doc3" class="yui-t3">
<div class="yui-b"></div>
<div class="yui-b"></div>
</div>
</body>
Use a wrapping div with an ID of yui-main to structurally indicate which block is the main block. This wrapper—not the source order—identifies the main block.
<body>
<div id="doc3" class="yui-t3">
<div id="yui-main">
<div class="yui-b"></div>
</div>
<div class="yui-b"></div>
</div>
</body>
Example: Main and secondary blocks sized and oriented with .yui-t3 Template Preset
Again, regardless of what values you choose in the other steps, you can always toggle between these Template Presets by toggling the class value of your document-wrapping div. It’s really that simple.
Step 3: Nest and Stack Grid Structures.
The bulk of the power of the system is in this third step. The key is that columns are built by parents telling children how to behave. By default, two children each consume half of their parent’s area. Put two units inside a grid structure, and they will sit side-by-side, and they will each take up half the space. Nest this structure and two columns become four. Stack them for rows of columns.
An Even Number of Columns
The default behavior creates two evenly-distributed columns. It’s easy. Define one parent grid with .yui-g (“g” for grid) and two child units with .yui-u (“u” for unit). The code looks like this:
<div class="yui-g">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
Be sure to indicate the “first“ unit because the :first-child pseudo-class selector isn’t supported across all A-grade browsers. It’s unfortunate we need to add this, but luckily it’s not out of place in the markup layer since it is structural information.
Example: Two evenly-distributed columns in the main content block
An Odd Number of Columns
The default system does not work for an odd number of columns without using the included “Special Grids” classes. To create three evenly distributed columns, use the “yui-gb“ Special Grid:
<div class="yui-gb">
<div class="yui-u first"></div>
<div class="yui-u"></div>
<div class="yui-u"></div>
</div>
Example: Three evenly distributed columns in the main content block
Uneven Column Distribution
Special Grids are also used for unevenly distributed column widths. For example, .yui-ge tells the first unit (column) to take up 75% of the parent’s space and the other unit to take just 25%.
<div class="yui-ge">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
Example: Two columns in the main content block split 75%-25%
Putting It All Together
Start with a full-width fluid page (div#doc3). Make the secondary block 180px wide on the right (div.yui-t4). Create three rows of columns: Three evenly distributed columns in the first row (div.yui-gb), two uneven columns (66%-33%) in the second row (div.yui-gc), and two evenly distributed columns in the thrid row.
<body>
<!-- choose fluid page and Template Preset -->
<div id="doc3" class="yui-t4">
<!-- main content block -->
<div id="yui-main">
<div class="yui-b">
<!-- stacked grid structure, Special Grid "b" -->
<div class="yui-gb">
<div class="yui-u first"></div>
<div class="yui-u"></div>
<div class="yui-u"></div>
</div>
<!-- stacked grid structure, Special Grid "c" -->
<div class="yui-gc">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
<!-- stacked grid structure -->
<div class="yui-g">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
</div>
</div>
<!-- secondary content block -->
<div class="yui-b"></div>
</div>
</body>
Example: A complex layout.
Wasn’t that easy? Now that you know the three “levers” of YUI Grids CSS, you’ll be creating headache-free fluid layouts faster than you can say “Peace on Earth”. |
2006 |
Nate Koechley |
natekoechley |
2006-12-20T00:00:00+00:00 |
https://24ways.org/2006/intricate-fluid-layouts/ |
code |
| 323 |
Introducing UDASSS! |
Okay. What’s that mean?
Unobtrusive Degradable Ajax Style Sheet Switcher!
Boy are you in for treat today ‘cause we’re gonna have a whole lotta Ajaxifida Unobtrucitosity CSS swappin’ Fun!
Okay are you really kidding? Nope. I’ve even impressed myself on this one. Unfortunately, I don’t have much time to tell you the ins and outs of what I actually did to get this to work. We’re talking JavaScript, CSS, PHP…Ajax. But don’t worry about that. I’ve always believed that a good A.P.I. is an invisible A.P.I… and this I felt I achieved. The only thing you need to know is how it works and what to do.
A Quick Introduction Anyway…
First of all, the idea is very simple. I wanted something just like what Paul Sowden put together in
Alternative Style: Working With Alternate Style Sheets from Alistapart Magazine EXCEPT a few minor (not-so-minor actually) differences which I’ve listed briefly below:
Allow users to switch styles without JavaScript enabled (degradable)
Preventing the F.O.U.C. before the window ‘load’ when getting preferred styles
Keep the JavaScript entirely off our markup (no onclick’s or onload’s)
Make it very very easy to implement (ok, Paul did that too)
What I did to achieve this was used server-side cookies instead of JavaScript cookies. Hence, PHP. However this isn’t a “PHP style switcher” – which is where Ajax comes in. For the extreme technical folks, no, there is no xml involved here, or even a callback response. I only say Ajax because everyone knows what ‘it’ means. With that said, it’s the Ajax that sets the cookies ‘on the fly’. Got it? Awesome!
What you need
Luckily, I’ve done the work for you. It’s all packaged up in a nice zip file (at the end…keep reading for now) – so from here on out,
just follow these instructions
As I’ve mentioned, one of the things we’ll be working with is PHP. So, first things first, open up a file called index and save it with a ‘.php’ extension.
Next, place the following text at the top of your document (even above your DOCTYPE)
<?php
require_once('utils/style-switcher.php');
// style sheet path[, media, title, bool(set as alternate)]
$styleSheet = new AlternateStyles();
$styleSheet->add('css/global.css','screen,projection'); // [Global Styles]
$styleSheet->add('css/preferred.css','screen,projection','Wog Standard'); // [Preferred Styles]
$styleSheet->add('css/alternate.css','screen,projection','Tiny Fonts',true); // [Alternate Styles]
$styleSheet->add('css/alternate2.css','screen,projection','Big O Fonts',true); // // [Alternate Styles]
$styleSheet->getPreferredStyles();
?>
The way this works is REALLY EASY. Pay attention closely.
Notice in the first line we’ve included our style-switcher.php file.
Next we instantiate a PHP class called AlternateStyles() which will allow us to configure our style sheets.
So for kicks, let’s just call our object $styleSheet
As part of the AlternateStyles object, there lies a public method called add. So naturally with our $styleSheet object, we can call it to (da – da-da-da!) Add Style Sheets!
How the add() method works
The add method takes in a possible four arguments, only one is required. However, you’ll want to add some… since the whole point is working with alternate style sheets.
$path can simply be a uri, absolute, or relative path to your style sheet. $media adds a media attribute to your style sheets. $title gives a name to your style sheets (via title attribute).$alternate (which shows boolean) simply tells us that these are the alternate style sheets.
add() Tips
For all global style sheets (meaning the ones that will always be seen and will not be swapped out), simply use the add method as shown next to // [Global Styles].
To add preferred styles, do the same, but add a ‘title’.
To add the alternate styles, do the same as what we’ve done to add preferred styles, but add the extra boolean and set it to true.
Note following when adding style sheets
Multiple global style sheets are allowed
You can only have one preferred style sheet (That’s a browser rule)
Feel free to add as many alternate style sheets as you like
Moving on
Simply add the following snippet to the <head> of your web document:
<script type="text/javascript" src="js/prototype.js"></script>
<script type="text/javascript" src="js/common.js"></script>
<script type="text/javascript" src="js/alternateStyles.js"></script>
<?php
$styleSheet->drop();
?>
Nothing much to explain here. Just use your copy & paste powers.
How to Switch Styles
Whether you knew it or not, this baby already has the built in ‘ubobtrusive’ functionality that lets you switch styles by the drop of any link with a class name of ‘altCss‘. Just drop them where ever you like in your document as follows:
<a class="altCss" href="index.php?css=Bog_Standard">Bog Standard</a>
<a class="altCss" href="index.php?css=Really_Small_Fonts">Small Fonts</a>
<a class="altCss" href="index.php?css=Large_Fonts">Large Fonts</a>
Take special note where the file is linking to. Yep. Just linking right back to the page we’re on. The only extra parameters we pass in is a variable called ‘css’ – and within that we append the names of our style sheets.
Also take very special note on the names of the style sheets have an under_score to take place of any spaces we might have.
Go ahead… play around and change the style sheet on the example page. Try disabling JavaScript and refreshing your browser. Still works!
Cool eh?
Well, I put this together in one night so it’s still a work in progress and very beta. If you’d like to hear more about it and its future development, be sure stop on by my site where I’ll definitely be maintaining it.
Download the beta anyway
Well this wouldn’t be fun if there was nothing to download. So we’re hooking you up so you don’t go home (or logoff) unhappy
Download U.D.A.S.S.S | V0.8
Merry Christmas!
Thanks for listening and I hope U.D.A.S.S.S. has been well worth your time and will bring many years of Ajaxy Style Switchin’ Fun!
Many Blessings, Merry Christmas and have a great new year! |
2005 |
Dustin Diaz |
dustindiaz |
2005-12-18T00:00:00+00:00 |
https://24ways.org/2005/introducing-udasss/ |
code |
| 322 |
Introduction to Scriptaculous Effects |
Gather around kids, because this year, much like in that James Bond movie with Denise Richards, Christmas is coming early… in the shape of scrumptuous smooth javascript driven effects at your every whim.
Now what I’m going to do, is take things down a notch. Which is to say, you don’t need to know much beyond how to open a text file and edit it to follow this article. Personally, I for instance can’t code to save my life.
Well, strictly speaking, that’s not entirely true. If my life was on the line, and the code needed was really simple and I wasn’t under any time constraints, then yeah maybe I could hack my way out of it
But my point is this: I’m not a programmer in the traditional sense of the word. In fact, what I do best, is scrounge code off of other people, take it apart and then put it back together with duct tape, chewing gum and dumb blind luck.
No, don’t run! That happens to be a good thing in this case. You see, we’re going to be implementing some really snazzy effects (which are considerably more relevant than most people are willing to admit) on your site, and we’re going to do it with the aid of Thomas Fuchs’ amazing Script.aculo.us library. And it will be like stealing candy from a child.
What Are We Doing?
I’m going to show you the very basics of implementing the Script.aculo.us javascript library’s Combination Effects. These allow you to fade elements on your site in or out, slide them up and down and so on.
Why Use Effects at All?
Before get started though, let me just take a moment to explain how I came to see smooth transitions as something more than smoke and mirror-like effects included for with little more motive than to dazzle and make parents go ‘uuh, snazzy’.
Earlier this year, I had the good fortune of meeting the kind, gentle and quite knowledgable Matt Webb at a conference here in Copenhagen where we were both speaking (though I will be the first to admit my little talk on Open Source Design was vastly inferior to Matt’s talk). Matt held a talk called Fixing Broken Windows (based on the Broken Windows theory), which really made an impression on me, and which I have since then referred back to several times.
You can listen to it yourself, as it’s available from Archive.org. Though since Matt’s session uses many visual examples, you’ll have to rely on your imagination for some of the examples he runs through during it. Also, I think it looses audio for a few seconds every once in a while.
Anyway, one of the things Matt talked a lot about, was how our eyes are wired to react to movement. The world doesn’t flickr. It doesn’t disappear or suddenly change and force us to look for the change. Things move smoothly in the real world. They do not pop up.
How it Works
Once the necessary files have been included, you trigger an effect by pointing it at the ID of an element. Simple as that.
Implementing the Effects
So now you know why I believe these effects have a place in your site, and that’s half the battle. Because you see, actually getting these effects up and running, is deceptively simple.
First, go and download the latest version of the library (as of this writing, it’s version 1.5 rc5). Unzip itand open it up.
Now we’re going to bypass the instructions in the readme file. Script.aculo.us can do a bunch of quite advanced things, but all we really want from it is its effects. And by sidestepping the rest of the features, we can shave off roughly 80KB of unnecessary javascript, which is well worth it if you ask me.
As with Drew’s article on Easy Ajax with Prototype, script.aculo.us also uses the Prototype framework by Sam Stephenson. But contrary to Drew’s article, you don’t have to download Prototype, as a version comes bundled with script.aculo.us (though feel free to upgrade to the latest version if you so please).
So in the unzipped folder, containing the script.aculo.us files and folder, go into ‘lib’ and grab the ‘prototype.js’ file. Move it to whereever you want to store the javascript files. Then fetch the ‘effects.js’ file from the ‘src’ folder and put it in the same place.
To make things even easier for you to get this up and running, I have prepared a small javascript snippet which does some checking to see what you’re trying to do. The script.aculo.us effects are all either ‘turn this off’ or ‘turn this on’. What this snippet does, is check to see what state the target currently has (is it on or off?) and then use the necessary effect.
You can either skip to the end and download the example code, or copy and paste this code into a file manually (I’ll refer to that file as combo.js):
Effect.OpenUp = function(element) {
element = $(element);
new Effect.BlindDown(element, arguments[1] || {});
}
Effect.CloseDown = function(element) {
element = $(element);
new Effect.BlindUp(element, arguments[1] || {});
}
Effect.Combo = function(element) {
element = $(element);
if(element.style.display == 'none') {
new Effect.OpenUp(element, arguments[1] || {});
}else {
new Effect.CloseDown(element, arguments[1] || {});
}
}
Currently, this code uses the BlindUp and BlindDown code, which I personally like, but there’s nothing wrong with you changing the effect-type into one of the other effects available.
Now, include the three files in the header of your code, like so:
<script src="prototype.js" type="text/javascript"></script>
<script src="effects.js" type="text/javascript"></script>
<script src="combo.js" type="text/javascript"></script>
Now insert the element you want to use the effect on, like so:
<div id="content" style="display: none;">Lorem ipsum dolor sit amet.</div>
The above element will start out invisible, and when triggered will be revealed. If you want it to start visible, simply remove the style parameter.
And now for the trigger
<a href="javascript:Effect.Combo('content');">Click Here</a>
And that, is pretty much it. Clicking the link should unfold the DIV targeted by the effect, in this case ‘content’.
Effect Options
Now, it gets a bit long-haired though. The documentation for script.aculo.us is next to non-existing, and because of that you’ll have to do some digging yourself to appreciate the full potentialof these effects.
First of all, what kind of effects are available? Well you can go to the demo page and check them out, or you can open the ‘effects.js’ file and have a look around, something I recommend doing regardlessly, to gain an overview of what exactly you’re dealing with.
If you dissect it for long enough, you can even distill some of the options available for the various effects. In the case of the BlindUp and BlindDown effect, which we’re using in our example (as triggered from combo.js), one of the things that would be interesting to play with would be the duration of the effect. If it’s too long, it will feel slow and unresponsive. Too fast and it will be imperceptible.
You set the options like so:
<a href="javascript:Effect.Combo('content', {duration: .2});">Click Here</a>
The change from the previous link being the inclusion of , {duration: .2}. In this case, I have lowered the duration to 0.2 second, to really make it feel snappy.
You can also go all-out and turn on all the bells and whistles of the Blind effect like so (slowed down to a duration of three seconds so you can see what’s going on):
<a href="javascript:Effect.Combo('content', {duration: 3, scaleX: true, scaleContent: true});">Click Here</a>
Conclusion
And that’s pretty much it. The rest is a matter of getting to know the rest of the effects and their options as well as finding out just when and where to use them. Remember the ancient Chinese saying: Less is more.
Download Example
I have prepared a very basic example, which you can download and use as a reference point. |
2005 |
Michael Heilemann |
michaelheilemann |
2005-12-12T00:00:00+00:00 |
https://24ways.org/2005/introduction-to-scriptaculous-effects/ |
code |
| 244 |
It’s Beginning to Look a Lot Like XSSmas |
I dread the office Secret Santa. I have a knack for choosing well-meaning but inappropriate presents, like a bottle of port for a teetotaller, a cheese-tasting experience for a vegan, or heaven forbid, Spurs socks for an Arsenal supporter. Ok, the last one was intentional.
It’s the same with gifting code. Once, I made a pattern library for A List Apart which I open sourced, and a few weeks later, a glaring security vulnerability was found in it. My gift was so generous that it enabled unrestricted access to any file on any public-facing server that hosted it.
With platforms like GitHub and npm, giving the gift of code is so easy it’s practically a no-brainer. This giant, open source yankee swap helps us do our jobs without starting from scratch with every project. But like any gift-giving, it’s also risky.
Vulnerabilities and Open Source
Open source code is not inherently more or less vulnerable than closed-source code. What makes it higher risk is that the same piece of code gets reused in lots of places, meaning a hacker can use the same exploit mechanism on the same vulnerable code in different apps.
Graph showing the number of open source vulnerabilities published per year, from the State of Open Source Security 2017
In the first 24 ways article this year, Katie referenced a few different types of vulnerability:
Cross-site Request Forgery (also known as CSRF)
SQL Injection
Cross-site Scripting (also known as XSS)
There are many more types of vulnerability, and those that live under the same category share similarities.
For example, my favourite – is it weird to have a favourite vulnerability? – is Cross Site Scripting (XSS), which allows for the injection of scripts into web pages. This is a really common vulnerability often unwittingly added by developers. OWASP (the Open Web Application Security Project) wrote a great article about how to prevent opening the door to XSS attacks – share it generously with your colleagues.
Most vulnerabilities like this are not added intentionally – they’re doors left ajar due to the way something has been scripted, like the over-generous code in my pattern library.
Others, though, are added intentionally. A few months ago, a hacker, disguised as a helpful elf, offered to take over the maintenance of a popular npm package that had been unmaintained for a couple of years. The owner had moved onto other projects, and was keen to see it continue to be maintained by someone else, so transferred ownership. Fast-forward 3 months, it was discovered that the individual had quietly added a malicious package to the codebase, and the obfuscated code in it had been unwittingly installed onto thousands of apps. The code added was designed to harvest Bitcoin if it was run alongside another application. It was only spotted due to a developer’s curiosity.
Another tactic to get developers to unwittingly install malicious packages into their codebase is “typosquatting” – back in August last year, npm reported that a user had been publishing packages with very similar names to popular packages (for example, crossenv instead of cross-env).
This is a big wakeup call for open source maintainers. Techniques like this are likely to be used more as the maintenance of open source libraries becomes an increasing burden to their owners. After all, starting a new project often has a greater reward than maintaining an existing one, but remember, an open source library is for life, not just for Christmas.
Santa’s on his sleigh
If you use open source libraries, chances are that these libraries also use open source libraries. Your app may only have a handful of dependencies, but tucked in the back of that sleigh may be a whole extra sack of dependencies known as deep dependencies (ones that you didn’t directly install, but are dependencies of that dependency), and these can contain vulnerabilities too.
Let’s look at the npm package santa as an example. santa has 8 direct dependencies listed on npm. That seems pretty manageable. But that’s just the tip of the iceberg – have a look at the full dependency tree which contains 109 dependencies – more dependencies than there are Christmas puns in this article. Only one of these direct dependencies has a vulnerability (at the time of writing), but there are actually 13 other known vulnerabilities in santa, which have been introduced through its deeper dependencies.
Fixing vulnerabilities – the ultimate christmas gift
If you’re a maintainer of open source libraries, taking good care of them is the ultimate gift you can give. Keep your dependencies up to date, use a security tool to monitor and alert you when new vulnerabilities are found in your code, and fix or patch them promptly. This will help keep the whole open source ecosystem healthy.
When you find out about a new vulnerability, you have some options:
Fix the vulnerability via an upgrade
You can often fix a vulnerability by upgrading the library to the latest version. Make sure you’re using software that monitors your dependencies for new security issues and lets you know when a fix is ready, otherwise you may be unwittingly using a vulnerable version.
Patch the vulnerable code
Sometimes, a fix for a vulnerable library isn’t possible. This is often the case when a library is no longer being maintained, or the version of the library being used might be so out of date that upgrading it would cause a breaking change. Patches are bits of code that will fix that particular issue, but won’t change anything else.
Switch to a different library
If the library you’re using has no fix or patch, you may be better of switching it out for another one, particularly if it looks like it’s being unmaintained.
Responsibly disclosing vulnerabilities
Knowing how to responsibly disclose vulnerabilities is something I’m ashamed to admit that I didn’t know about before I joined a security company. But it’s so important! On discovering a new vulnerability, a developer has a few options:
A malicious developer will exploit that vulnerability for their own gain.
A reckless (or inexperienced) developer will disclose that vulnerability to the world without following a responsible disclosure process. This opens the door to an unethical developer exploiting the vulnerability. At Snyk, we monitor social media for mentions of newly found vulnerabilities so we can add them to our database and share fixes before they get exploited.
An ethical and aware developer will follow what’s known as a “responsible disclosure process”. They will contact the maintainer of the code privately, allowing reasonable time for them to release a fix for the issue and to give others who use that vulnerable code a chance to fix it too.
It’s important to understand this process if you’re a maintainer or contributor of code. It can be daunting when a report comes in, but understanding and following the right steps will help reduce the risk to the people who use that code.
So what does responsible disclosure look like? I’ll take Node.js’s security disclosure policy as an example. They ask that all security issues that are found in Node.js are reported there. (There’s a separate process for bug found in third-party npm packages). Once you’ve reported a vulnerability, they promise to acknowledge it within 24 hours, and to give a more detailed response within 48 hours. If they find that the issue is indeed a security bug, they’ll give you regular updates about the progress they’re making towards fixing it. As part of this, they’ll figure out which versions are affected, and prepare fixes for them. They’ll assign the vulnerability a CVE (Common Vulnerabilities and Exposures) ID and decide on an embargo date for public disclosure. On the date of the embargo, they announce the vulnerability in their Node.js security mailing list and deploy fixes to nodejs.org.
Tim Kadlec published an in-depth article about responsible disclosures if you’re interested in knowing more. It has some interesting horror stories of what happened when the disclosure process was not followed.
Encourage responsible disclosure
Add a SECURITY.md file to your project so someone who wants to message you about a vulnerability can do so without having to hunt around for contact details. Last year, Snyk published a State of Open Source Security report that found 79.5% of maintainers do not have a public disclosure policy. Those that did were considerably more likely to get notified privately about a vulnerability – 73% of maintainers who had one had been notified, vs 21% of maintainers who hadn’t published one one.
Stats from the State of Open Source Security 2017
Bug bounties
Some companies run bug bounties to encourage the responsible disclosure of vulnerabilities. By offering a reward for finding and safely disclosing a vulnerability, it also reduces the enticement of exploiting a vulnerability over reporting it and getting a quick cash reward. Hackerone is a community of ethical hackers who pentest apps that have signed up for the scheme and get paid when they find a new vulnerability. Wordpress is one such participant, and you can see the long list of vulnerabilities that have been disclosed as part of that program.
If you don’t have such a bounty, be prepared to get the odd vulnerability extortion email. Scott Helme, who founded securityheaders.com and report-uri.com, wrote a post about some of the requests he gets for a report about a critical vulnerability in exchange for money.
On one hand, I want to be as responsible as possible and if my users are at risk then I need to know and patch this issue to protect them. On the other hand this is such irresponsible and unethical behaviour that interacting with this person seems out of the question.
A gift worth giving
It’s time to brush the dust off those old gifts that we shared and forgot about. Practice good hygiene and run them through your favourite security tool – I’m just a little biased towards Snyk, but as Katie mentioned, there’s also npm audit if you use Node.js, and most source code managers like GitHub and GitLab have basic vulnerability alert capabilities.
Stats from the State of Open Source Security 2017
Most importantly, patch or upgrade away those vulnerabilities away, and if you want to share that Christmas spirit, open fixes for your favourite open source projects, too. |
2018 |
Anna Debenham |
annadebenham |
2018-12-17T00:00:00+00:00 |
https://24ways.org/2018/its-beginning-to-look-a-lot-like-xssmas/ |
code |
| 241 |
Jank-Free Image Loads |
There are a few fundamental problems with embedding images in pages of hypertext; perhaps chief among them is this: text is very light and loads rather fast; images are much heavier and arrive much later. Consequently, millions (billions?) of times a day, a hapless Web surfer will start reading some text on a page, and then —
Your browser doesn’t support HTML5 video. Here is
a link to the video instead.
— oops! — an image pops in above it, pushing said text down the page, and our poor reader loses their place.
By default, partially-loaded pages have the user experience of a slippery fish, or spilled jar of jumping beans. For the rest of this article, I shall call that jarring, no-good jumpiness by its name: jank. And I’ll chart a path into a jank-free future – one in which it’s easy and natural to author <img> elements that load like this:
Your browser doesn’t support HTML5 video. Here is
a link to the video instead.
Jank is a very old problem, and there is a very old solution to it: the width and height attributes on <img>. The idea is: if we stick an image’s dimensions right into the HTML, browsers can know those dimensions before the image loads, and reserve some space on the layout for it so that nothing gets bumped down the page when the image finally arrives.
width
Specifies the intended width of the image in pixels. When given together with the height, this allows user agents to reserve screen space for the image before the image data has arrived over the network.
—The HTML 3.2 Specification, published on January 14 1997
Unfortunately for us, when width and height were first spec’d and implemented, layouts were largely fixed and images were usually only intended to render at their fixed, actual dimensions. When image sizing gets fluid, width and height get weird:
See the Pen fluid width + fixed height = distortion by Eric Portis (@eeeps) on CodePen.
width and height are too rigid for the responsive world. What we need, and have needed for a very long time, is a way to specify fixed aspect ratios, to pair with our fluid widths.
I have good news, bad news, and great news.
The good news is, there are ways to do this, now, that work in every browser. Responsible sites, and responsible developers, go through the effort to do them.
The bad news is that these techniques are all terrible, cumbersome hacks. They’re difficult to remember, difficult to understand, and they can interact with other pieces of CSS in unexpected ways.
So, the great news: there are two on-the-horizon web platform features that are trying to make no-jank, fixed-aspect-ratio, fluid-width images a natural part of the web platform.
aspect-ratio in CSS
The first proposed feature? An aspect-ratio property in CSS!
This would allow us to write CSS like this:
img {
width: 100%;
}
.thumb {
aspect-ratio: 1/1;
}
.hero {
aspect-ratio: 16/9;
}
This’ll work wonders when we need to set aspect ratios for whole classes of images, which are all sized to fit within pre-defined layout slots, like the .thumb and .hero images, above.
Alas, the harder problem, in my experience, is not images with known-ahead-of-time aspect ratios. It’s images – possibly user generated images – that can have any aspect ratio. The really tricky problem is unknown-when-you’re-writing-your-CSS aspect ratios that can vary per-image. Using aspect-ratio to reserve space for images like this requires inline styles:
<img src="image.jpg" style="aspect-ratio: 5/4" />
And inline styles give me the heebie-jeebies! As a web developer of a certain age, I have a tiny man in a blue beanie permanently embedded deep within my hindbrain, who cries out in agony whenever I author a style="" attribute. And you know what? The old man has a point! By sticking super-high-specificity inline styles in my content, I’m cutting off my, (or anyone else’s) ability to change those aspect ratios, for whatever reason, later.
How might we specify aspect ratios at a lower level? How might we give browsers information about an image’s dimensions, without giving them explicit instructions about how to style it?
I’ll tell you: we could give browsers the intrinsic aspect ratio of the image in our HTML, rather than specifying an extrinsic aspect ratio!
A brief note on intrinsic and extrinsic sizing
What do I mean by “intrinsic” and “extrinsic?”
The intrinsic size of an image is, put simply, how big it’d be if you plopped it onto a page and applied no CSS to it whatsoever. An 800×600 image has an intrinsic width of 800px.
The extrinsic size of an image, then, is how large it ends up after CSS has been applied. Stick a width: 300px rule on that same 800×600 image, and its intrinsic size (accessible via the Image.naturalWidth property, in JavaScript) doesn’t change: its intrinsic size is still 800px. But this image now has an extrinsic size (accessible via Image.clientWidth) of 300px.
It surprised me to learn this year that height and width are interpreted as presentational hints and that they end up setting extrinsic dimensions (albeit ones that, unlike inline styles, have absolutely no specificity).
CSS aspect-ratio lets us avoid setting extrinsic heights and widths – and instead lets us give images (or anything else) an extrinsic aspect ratio, so that as soon as we set one dimension (possibly to a fluid width, like 100%!), the other dimension is set automatically in relation to it.
The last tool I’m going to talk about gets us out of the extrinsic sizing game all together — which, I think, is only appropriate for a feature that we’re going to be using in HTML.
intrinsicsize in HTML
The proposed intrinsicsize attribute will let you do this:
<img src="image.jpg" intrinsicsize="800x600" />
That tells the browser, “hey, this image.jpg that I’m using here – I know you haven’t loaded it yet but I’m just going to let you know right away that it’s going to have an intrinsic size of 800×600.” This gives the browser enough information to reserve space on the layout for the image, and ensures that any and all extrinsic sizing instructions, specified in our CSS, will layer cleanly on top of this, the image’s intrinsic size.
You may ask (I did!): wait, what if my <img> references multiple resources, which all have different intrinsic sizes? Well, if you’re using srcset, intrinsicsize is a bit of a misnomer – what the attribute will do then, is specify an intrinsic aspect ratio:
<img
srcset="300x200.jpg 300w,
600x400.jpg 600w,
900x600.jpg 900w,
1200x800.jpg 1200w"
sizes="75vw"
intrinsicsize="3x2" />
In the future (and behind the “Experimental Web Platform Features” flag right now, in Chrome 71+), asking this image for its .naturalWidth would not return 3 – it will return whatever 75vw is, given the current viewport width. And Image.naturalHeight will return that width, divided by the intrinsic aspect ratio: 3/2.
Can’t wait
I seem to have gotten myself into the weeds a bit. Sizing on the web is complicated!
Don’t let all of these details bury the big takeaway here: sometime soon (🤞 2019‽ 🤞), we’ll be able to toss our terrible aspect-ratio hacks into the dustbin of history, get in the habit of setting aspect-ratios in CSS and/or intrinsicsizes in HTML, and surf a less-frustrating, more-performant, less-janky web. I can’t wait! |
2018 |
Eric Portis |
ericportis |
2018-12-21T00:00:00+00:00 |
https://24ways.org/2018/jank-free-image-loads/ |
code |
| 153 |
JavaScript Internationalisation |
or: Why Rudolph Is More Than Just a Shiny Nose
Dunder sat, glumly staring at the computer screen.
“What’s up, Dunder?” asked Rudolph, entering the stable and shaking off the snow from his antlers.
“Well,” Dunder replied, “I’ve just finished coding the new reindeer intranet Santa Claus asked me to do. You know how he likes to appear to be at the cutting edge, talking incessantly about Web 2.0, AJAX, rounded corners; he even spooked Comet recently by talking about him as if he were some pushy web server.
“I’ve managed to keep him happy, whilst also keeping it usable, accessible, and gleaming — and I’m still on the back row of the sleigh! But anyway, given the elves will be the ones using the site, and they come from all over the world, the site is in multiple languages. Which is great, except when it comes to the preview JavaScript I’ve written for the reindeer order form. Here, have a look…”
As he said that, he brought up the textileRef:8234272265470b85d91702:linkStartMarker:“order
form in French”:/examples/javascript-internationalisation/initial.fr.html on the screen. (Same in English).
“Looks good,” said Rudolph.
“But if I add some items,” said Dunder, “the preview appears in English, as it’s hard-coded in the JavaScript. I don’t want separate code for each language, as that’s just silly — I thought about just having if statements, but that doesn’t scale at all…”
“And there’s more, you aren’t displaying large numbers in French properly, either,” added Rudolph, who had been playing and looking at part of the source code:
function update_text() {
var hay = getValue('hay');
var carrots = getValue('carrots');
var bells = getValue('bells');
var total = 50 * bells + 30 * hay + 10 * carrots;
var out = 'You are ordering '
+ pretty_num(hay) + ' bushel' + pluralise(hay) + ' of hay, '
+ pretty_num(carrots) + ' carrot' + pluralise(carrots)
+ ', and ' + pretty_num(bells) + ' shiny bell' + pluralise(bells)
+ ', at a total cost of <strong>' + pretty_num(total)
+ '</strong> gold pieces. Thank you.';
document.getElementById('preview').innerHTML = out;
}
function pretty_num(n) {
n += '';
var o = '';
for (i=n.length; i>3; i-=3) {
o = ',' + n.slice(i-3, i) + o;
}
o = n.slice(0, i) + o;
return o;
}
function pluralise(n) {
if (n!=1) return 's';
return '';
}
“Oh, botheration!” cried Dunder. “This is just so complicated.”
“It doesn’t have to be,” said Rudolph, “you just have to think about things in a slightly different way from what you’re used to. As we’re only a simple example, we won’t be able to cover all possibilities, but for starters, we need some way of providing different information to the script dependent on the language. We’ll create a global i18n object, say, and fill it with the correct language information. The first variable we’ll need will be a thousands separator, and then we can change the pretty_num function to use that instead:
function pretty_num(n) {
n += '';
var o = '';
for (i=n.length; i>3; i-=3) {
o = i18n.thousands_sep + n.slice(i-3, i) + o;
}
o = n.slice(0, i) + o;
return o;
}
“The i18n object will also contain our translations, which we will access through a function called _() — that’s just an underscore. Other languages have a function of the same name doing the same thing. It’s very simple:
function _(s) {
if (typeof(i18n)!='undefined' && i18n[s]) {
return i18n[s];
}
return s;
}
“So if a translation is available and provided, we’ll use that; otherwise we’ll default to the string provided — which is helpful if the translation begins to lag behind the site’s text at all, as at least something will be output.”
“Got it,” said Dunder. “ _('Hello Dunder') will print the translation of that string, if one exists, ‘Hello Dunder’ if not.”
“Exactly. Moving on, your plural function breaks even in English if we have a word where the plural doesn’t add an s — like ‘children’.”
“You’re right,” said Dunder. “How did I miss that?”
“No harm done. Better to provide both singular and plural words to the function and let it decide which to use, performing any translation as well:
function pluralise(s, p, n) {
if (n != 1) return _(p);
return _(s);
}
“We’d have to provide different functions for different languages as we employed more elves and got more complicated — for example, in Polish, the word ‘file’ pluralises like this: 1 plik, 2-4 pliki, 5-21 plików, 22-24 pliki, 25-31 plików, and so on.” (More information on plural forms)
“Gosh!”
“Next, as different languages have different word orders, we must stop using concatenation to construct sentences, as it would be impossible for other languages to fit in; we have to keep coherent strings together. Let’s rewrite your update function, and then go through it:
function update_text() {
var hay = getValue('hay');
var carrots = getValue('carrots');
var bells = getValue('bells');
var total = 50 * bells + 30 * hay + 10 * carrots;
hay = sprintf(pluralise('%s bushel of hay', '%s bushels of hay', hay), pretty_num(hay));
carrots = sprintf(pluralise('%s carrot', '%s carrots', carrots), pretty_num(carrots));
bells = sprintf(pluralise('%s shiny bell', '%s shiny bells', bells), pretty_num(bells));
var list = sprintf(_('%s, %s, and %s'), hay, carrots, bells);
var out = sprintf(_('You are ordering %s, at a total cost of <strong>%s</strong> gold pieces.'),
list, pretty_num(total));
out += ' ';
out += _('Thank you.');
document.getElementById('preview').innerHTML = out;
}
“ sprintf is a function in many other languages that, given a format string and some variables, slots the variables into place within the string. JavaScript doesn’t have such a function, so we’ll write our own. Again, keep it simple for now, only integers and strings; I’m sure more complete ones can be found on the internet.
function sprintf(s) {
var bits = s.split('%');
var out = bits[0];
var re = /^([ds])(.*)$/;
for (var i=1; i<bits.length; i++) {
p = re.exec(bits[i]);
if (!p || arguments[i]==null) continue;
if (p[1] == 'd') {
out += parseInt(arguments[i], 10);
} else if (p[1] == 's') {
out += arguments[i];
}
out += p[2];
}
return out;
}
“Lastly, we need to create one file for each language, containing our i18n object, and then include that from the relevant HTML. Here’s what a blank translation file would look like for your order form:
var i18n = {
thousands_sep: ',',
"%s bushel of hay": '',
"%s bushels of hay": '',
"%s carrot": '',
"%s carrots": '',
"%s shiny bell": '',
"%s shiny bells": '',
"%s, %s, and %s": '',
"You are ordering %s, at a total cost of <strong>%s</strong> gold pieces.": '',
"Thank you.": ''
};
“If you implement this across the intranet, you’ll want to investigate the xgettext program, which can automatically extract all strings that need translating from all sorts of code files into a standard .po file (I think Python mode works best for JavaScript). You can then use a different program to take the translated .po file and automatically create the language-specific JavaScript files for us.” (e.g. German .po file for PledgeBank, mySociety’s .po-.js script, example output)
With a flourish, Rudolph finished editing. “And there we go, localised JavaScript in English, French, or German, all using the same main code.”
“Thanks so much, Rudolph!” said Dunder.
“I’m not just a pretty nose!” Rudolph quipped. “Oh, and one last thing — please comment liberally explaining the context of strings you use. Your translator will thank you, probably at the same time as they point out the four hundred places you’ve done something in code that only works in your language and no-one else’s…”
Thanks to Tim Morley and Edmund Grimley Evans for the French and German translations respectively. |
2007 |
Matthew Somerville |
matthewsomerville |
2007-12-08T00:00:00+00:00 |
https://24ways.org/2007/javascript-internationalisation/ |
code |
| 37 |
JavaScript Modules the ES6 Way |
JavaScript admittedly has plenty of flaws, but one of the largest and most prominent is the lack of a module system: a way to split up your application into a series of smaller files that can depend on each other to function correctly.
This is something nearly all other languages come with out of the box, whether it be Ruby’s require, Python’s import, or any other language you’re familiar with. Even CSS has @import! JavaScript has nothing of that sort, and this has caused problems for application developers as they go from working with small websites to full client-side applications. Let’s be clear: it doesn’t mean the new module system in the upcoming version of JavaScript won’t be useful to you if you’re building smaller websites rather than the next Instagram.
Thankfully, the lack of a module system will soon be a problem of the past. The next version of JavaScript, ECMAScript 6, will bring with it a full-featured module and dependency management solution for JavaScript. The bad news is that it won’t be landing in browsers for a while yet – but the good news is that the specification for the module system and how it will look has been finalised. The even better news is that there are tools available to get it all working in browsers today without too much hassle. In this post I’d like to give you the gift of JS modules and show you the syntax, and how to use them in browsers today. It’s much simpler than you might think.
What is ES6?
ECMAScript is a scripting language that is standardised by a company called Ecma International. JavaScript is an implementation of ECMAScript. ECMAScript 6 is simply the next version of the ECMAScript standard and, hence, the next version of JavaScript. The spec aims to be fully comfirmed and complete by the end of 2014, with a target initial release date of June 2015. It’s impossible to know when we will have full feature support across the most popular browsers, but already some ES6 features are landing in the latest builds of Chrome and Firefox. You shouldn’t expect to be able to use the new features across browsers without some form of additional tooling or library for a while yet.
The ES6 module spec
The ES6 module spec was fully confirmed in July 2014, so all the syntax I will show you in this article is not expected to change. I’ll first show you the syntax and the new APIs being added to the language, and then look at how to use them today. There are two parts to the new module system. The first is the syntax for declaring modules and dependencies in your JS files, and the second is a programmatic API for loading in modules manually. The first is what most people are expected to use most of the time, so it’s what I’ll focus on more.
Module syntax
The key thing to understand here is that modules have two key components. First, they have dependencies. These are things that the module you are writing depends on to function correctly. For example, if you were building a carousel module that used jQuery, you would say that jQuery is a dependency of your carousel. You import these dependencies into your module, and we’ll see how to do that in a minute. Second, modules have exports. These are the functions or variables that your module exposes publicly to anything that imports it. Using jQuery as the example again, you could say that jQuery exports the $ function. Modules that depend on and hence import jQuery get access to the $ function, because jQuery exports it.
Another important thing to note is that when I discuss a module, all I really mean is a JavaScript file. There’s no extra syntax to use other than the new ES6 syntax. Once ES6 lands, modules and files will be analogous.
Named exports
Modules can export multiple objects, which can be either plain old variables or JavaScript functions. You denote something to be exported with the export keyword:
export function double(x) {
return x + x;
};
You can also store something in a variable then export it. If you do that, you have to wrap the variable in a set of curly braces.
var double = function(x) {
return x + x;
}
export { double };
A module can then import the double function like so:
import { double } from 'mymodule';
double(2); // 4
Again, curly braces are required around the variable you would like to import. It’s also important to note that from 'mymodule' will look for a file called mymodule.js in the same directory as the file you are requesting the import from. There is no need to add the .js extension.
The reason for those extra braces is that this syntax lets you export multiple variables:
var double = function(x) {
return x + x;
}
var square = function(x) {
return x * x;
}
export { double, square }
I personally prefer this syntax over the export function …, but only because it makes it much clearer to me what the module exports. Typically I will have my export {…} line at the bottom of the file, which means I can quickly look in one place to determine what the module is exporting.
A file importing both double and square can do so in just the way you’d expect:
import { double, square } from 'mymodule';
double(2); // 4
square(3); // 9
With this approach you can’t easily import an entire module and all its methods. This is by design – it’s much better and you’re encouraged to import just the functions you need to use.
Default exports
Along with named exports, the system also lets a module have a default export. This is useful when you are working with a large library such as jQuery, Underscore, Backbone and others, and just want to import the entire library. A module can define its default export (it can only ever have one default export) like so:
export default function(x) {
return x + x;
}
And that can be imported:
import double from 'mymodule';
double(2); // 4
This time you do not use the curly braces around the name of the object you are importing. Also notice how you can name the import whatever you’d like. Default exports are not named, so you can import them as anything you like:
import christmas from 'mymodule';
christmas(2); // 4
The above is entirely valid.
Although it’s not something that is used too often, a module can have both named exports and a default export, if you wish.
One of the design goals of the ES6 modules spec was to favour default exports. There are many reasons behind this, and there is a very detailed discussion on the ES Discuss site about it. That said, if you find yourself preferring named exports, that’s fine, and you shouldn’t change that to meet the preferences of those designing the spec.
Programmatic API
Along with the syntax above, there is also a new API being added to the language so you can programmatically import modules. It’s pretty rare you would use this, but one obvious example is loading a module conditionally based on some variable or property. You could easily import a polyfill, for example, if the user’s browser didn’t support a feature your app relied on. An example of doing this is:
if(someFeatureNotSupported) {
System.import('my-polyfill').then(function(myPolyFill) {
// use the module from here
});
}
System.import will return a promise, which, if you’re not familiar, you can read about in this excellent article on HTMl5 Rocks by Jake Archibald. A promise basically lets you attach callback functions that are run when the asynchronous operation (in this case, System.import), is complete.
This programmatic API opens up a lot of possibilities and will also provide hooks to allow you to register callbacks that will run at certain points in the lifetime of a module. Those hooks and that syntax are slightly less set in stone, but when they are confirmed they will provide really useful functionality. For example, you could write code that would run every module that you import through something like JSHint before importing it. In development that would provide you with an easy way to keep your code quality high without having to run a command line watch task.
How to use it today
It’s all well and good having this new syntax, but right now it won’t work in any browser – and it’s not likely to for a long time. Maybe in next year’s 24 ways there will be an article on how you can use ES6 modules with no extra work in the browser, but for now we’re stuck with a bit of extra work.
ES6 module transpiler
One solution is to use the ES6 module transpiler, a compiler that lets you write your JavaScript using the ES6 module syntax (actually a subset of it – not quite everything is supported, but the main features are) and have it compiled into either CommonJS-style code (CommonJS is the module specification that NodeJS and Browserify use), or into AMD-style code (the spec RequireJS uses). There are also plugins for all the popular build tools, including Grunt and Gulp.
The advantage of using this transpiler is that if you are already using a tool like RequireJS or Browserify, you can drop the transpiler in, start writing in ES6 and not worry about any additional work to make the code work in the browser, because you should already have that set up already. If you don’t have any system in place for handling modules in the browser, using the transpiler doesn’t really make sense. Remember, all this does is convert ES6 module code into CommonJS- or AMD-compliant JavaScript. It doesn’t do anything to help you get that code running in the browser, but if you have that part sorted it’s a really nice addition to your workflow. If you would like a tutorial on how to do this, I wrote a post back in June 2014 on using ES6 with the ES6 module transpiler.
SystemJS
Another solution is SystemJS. It’s the best solution in my opinion, particularly if you are starting a new project from scratch, or want to use ES6 modules on a project where you have no current module system in place. SystemJS is a spec-compliant universal module loader: it loads ES6 modules, AMD modules, CommonJS modules, as well as modules that just add a variable to the global scope (window, in the browser).
To load in ES6 files, SystemJS also depends on two other libraries: the ES6 module loader polyfill; and Traceur. Traceur is best accessed through the bower-traceur package, as the main repository doesn’t have an easy to find downloadable version. The ES6 module load polyfill implements System.import, and lets you load in files using it. Traceur is an ES6-to-ES5 module loader. It takes code written in ES6, the newest version of JavaScript, and transpiles it into ES5, the version of JavaScript widely implemented in browsers. The advantage of this is that you can play with the new features of the language today, even though they are not supported in browsers. The drawback is that you have to run all your files through Traceur every time you save them, but this is easily automated. Additionally, if you use SystemJS, the Traceur compilation is done automatically for you.
All you need to do to get SystemJS running is to add a <script> element to load SystemJS into your webpage. It will then automatically load the ES6 module loader and Traceur files when it needs them. In your HTML you then need to use System.import to load in your module:
<script>
System.import('./app');
</script>
When you load the page, app.js will be asynchronously loaded. Within app.js, you can now use ES6 modules. SystemJS will detect that the file is an ES6 file, automatically load Traceur, and compile the file into ES5 so that it works in the browser. It does all this dynamically in the browser, but there are tools to bundle your application in production, so it doesn’t make a lot of requests on the live site. In development though, it makes for a really nice workflow.
When working with SystemJS and modules in general, the best approach is to have a main module (in our case app.js) that is the main entry point for your application. app.js should then be responsible for loading all your application’s modules. This forces you to keep your application organised by only loading one file initially, and having the rest dealt with by that file.
SystemJS also provides a workflow for bundling your application together into one file.
Conclusion
ES6 modules may be at least six months to a year away (if not more) but that doesn’t mean they can’t be used today. Although there is an overhead to using them now – with the work required to set up SystemJS, the module transpiler, or another solution – that doesn’t mean it’s not worthwhile. Using any module system in the browser, whether that be RequireJS, Browserify or another alternative, requires extra tooling and libraries to support it, and I would argue that the effort to set up SystemJS is no greater than that required to configure any other tool. It also comes with the extra benefit that when the syntax is supported in browsers, you get a free upgrade. You’ll be able to remove SystemJS and have everything continue to work, backed by the native browser solution.
If you are starting a new project, I would strongly advocate using ES6 modules. It is a syntax and specification that is not going away at all, and will soon be supported in browsers. Investing time in learning it now will pay off hugely further down the road.
Further reading
If you’d like to delve further into ES6 modules (or ES6 generally) and using them today, I recommend the following resources:
ECMAScript 6 modules: the final syntax by Axel Rauschmayer
Practical Workflows for ES6 Modules by Guy Bedford
ECMAScript 6 resources for the curious JavaScripter by Addy Osmani
Tracking ES6 support by Addy Osmani
ES6 Tools List by Addy Osmani
Using Grunt and the ES6 Module Transpiler by Thomas Boyt
JavaScript Modules and Dependencies with jspm by myself
Using ES6 Modules Today by Guy Bedford |
2014 |
Jack Franklin |
jackfranklin |
2014-12-03T00:00:00+00:00 |
https://24ways.org/2014/javascript-modules-the-es6-way/ |
code |
| 11 |
JavaScript: Taking Off the Training Wheels |
JavaScript is the third pillar of front-end web development. Of those pillars, it is both the most powerful and the most complex, so it’s understandable that when 24 ways asked, “What one thing do you wish you had more time to learn about?”, a number of you answered “JavaScript!”
This article aims to help you feel happy writing JavaScript, and maybe even without libraries like jQuery. I can’t comprehensively explain JavaScript itself without writing a book, but I hope this serves as a springboard from which you can jump to other great resources.
Why learn JavaScript?
So what’s in it for you? Why take the next step and learn the fundamentals?
Confidence with jQuery
If nothing else, learning JavaScript will improve your jQuery code; you’ll be comfortable writing jQuery from scratch and feel happy bending others’ code to your own purposes. Writing efficient, fast and bug-free jQuery is also made much easier when you have a good appreciation of JavaScript, because you can look at what jQuery is really doing. Understanding how JavaScript works lets you write better jQuery because you know what it’s doing behind the scenes. When you need to leave the beaten track, you can do so with confidence.
In fact, you could say that jQuery’s ultimate goal is not to exist: it was invented at a time when web APIs were very inconsistent and hard to work with. That’s slowly changing as new APIs are introduced, and hopefully there will come a time when jQuery isn’t needed.
An example of one such change is the introduction of the very useful document.querySelectorAll. Like jQuery, it converts a CSS selector into a list of matching elements. Here’s a comparison of some jQuery code and the equivalent without.
$('.counter').each(function (index) {
$(this).text(index + 1);
});
var counters = document.querySelectorAll('.counter');
[].slice.call(counters).forEach(function (elem, index) {
elem.textContent = index + 1;
});
Solving problems no one else has!
When you have to go to the internet to solve a problem, you’re forever stuck reusing code other people wrote to solve a slightly different problem to your own. Learning JavaScript will allow you to solve problems in your own way, and begin to do things nobody else ever has.
Node.js
Node.js is a non-browser environment for running JavaScript, and it can do just about anything! But if that sounds daunting, don’t worry: the Node community is thriving, very friendly and willing to help.
I think Node is incredibly exciting. It enables you, with one language, to build complete websites with complex and feature-filled front- and back-ends. Projects that let users log in or need a database are within your grasp, and Node has a great ecosystem of library authors to help you build incredible things. Exciting!
Here’s an example web server written with Node. http is a module that allows you to create servers and, like jQuery’s $.ajax, make requests. It’s a small amount of code to do something complex and, while working with Node is different from writing front-end code, it’s certainly not out of your reach.
var http = require('http');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello World');
}).listen(1337);
console.log('Server running at http://localhost:1337/');
Grunt and other website tools
Node has brought in something of a renaissance in tools that run in the command line, like Yeoman and Grunt. Both of these rely heavily on Node, and I’ll talk a little bit about Grunt here.
Grunt is a task runner, and many people use it for compiling Sass or compressing their site’s JavaScript and images. It’s pretty cool. You configure Grunt via the gruntfile.js, so JavaScript skills will come in handy, and since Grunt supports plug-ins built with JavaScript, knowing it unlocks the bucketloads of power Grunt has to offer.
Ways to improve your skills
So you know you want to learn JavaScript, but what are some good ways to learn and improve? I think the answer to that is different for different people, but here are some ideas.
Rebuild a jQuery app
Converting a jQuery project to non-jQuery code is a great way to explore how you modify elements on the page and make requests to the server for data. My advice is to focus on making it work in one modern browser initially, and then go cross-browser if you’re feeling adventurous. There are many resources for directly comparing jQuery and non-jQuery code, like Jeffrey Way’s jQuery to JavaScript article.
Find a mentor
If you think you’d work better on a one-to-one basis then finding yourself a mentor could be a brilliant way to learn. The JavaScript community is very friendly and many people will be more than happy to give you their time. I’d look out for someone who’s active and friendly on Twitter, and does the kind of work you’d like to do. Introduce yourself over Twitter or send them an email. I wouldn’t expect a full tutoring course (although that is another option!) but they’ll be very glad to answer a question and any follow-ups every now and then.
Go to a workshop
Many conferences and local meet-ups run workshops, hosted by experts in a particular field. See if there’s one in your area. Workshops are great because you can ask direct questions, and you’re in an environment where others are learning just like you are — no need to learn alone!
Set yourself challenges
This is one way I like to learn new things. I have a new thing that I’m not very good at, so I pick something that I think is just out of my reach and I try to build it. It’s learning by doing and, even if you fail, it can be enormously valuable.
Where to start?
If you’ve decided learning JavaScript is an important step for you, your next question may well be where to go from here.
I’ve collected some links to resources I know of or use, with some discussion about why you might want to check a particular site out. I hope this serves as a springboard for you to go out and learn as much as you want.
Beginner
If you’re just getting started with JavaScript, I’d recommend heading to one of these places. They cover the basics and, in some cases, a little more advanced stuff. They’re all reputable sources (although, I’ve included something I wrote — you can decide about that one!) and will not lead you astray.
jQuery’s JavaScript 101 is a great first resource for JavaScript that will give you everything you need to work with jQuery like a pro.
Codecademy’s JavaScript Track is a small but useful JavaScript course. If you like learning interactively, this could be one for you.
HTMLDog’s JavaScript Tutorials take you right through from the basics of code to a brief introduction to newer technology like Node and Angular. [Disclaimer: I wrote this stuff, so it comes with a hazard warning!]
The tuts+ jQuery to JavaScript mentioned earlier is great for seeing how jQuery code looks when converted to pure JavaScript.
Getting in-depth
For more comprehensive documentation and help I’d recommend adding these places to your list of go-tos.
MDN: the Mozilla Developer Network is the first place I go for many JavaScript questions. I mostly find myself there via a search, but it’s a great place to just go and browse.
Axel Rauschmayer’s 2ality is a stunning collection of articles that will take you deep into JavaScript. It’s certainly worth looking at.
Addy Osmani’s JavaScript Design Patterns is a comprehensive collection of patterns for writing high quality JavaScript, particularly as you (I hope) start to write bigger and more complex applications.
And finally…
I think the key to learning anything is curiosity and perseverance. If you have a question, go out and search for the answer, even if you have no idea where to start. Keep going and going and eventually you’ll get there. I bet you’ll learn a whole lot along the way. Good luck!
Many thanks to the people who gave me their time when I was working on this article: Tom Oakley, Jack Franklin, Ben Howdle and Laura Kalbag. |
2013 |
Tom Ashworth |
tomashworth |
2013-12-05T00:00:00+00:00 |
https://24ways.org/2013/javascript-taking-off-the-training-wheels/ |
code |
| 161 |
Keeping JavaScript Dependencies At Bay |
As we are writing more and more complex JavaScript applications we run into issues that have hitherto (god I love that word) not been an issue. The first decision we have to make is what to do when planning our app: one big massive JS file or a lot of smaller, specialised files separated by task.
Personally, I tend to favour the latter, mainly because it allows you to work on components in parallel with other developers without lots of clashes in your version control. It also means that your application will be more lightweight as you only include components on demand.
Starting with a global object
This is why it is a good plan to start your app with one single object that also becomes the namespace for the whole application, say for example myAwesomeApp:
var myAwesomeApp = {};
You can nest any necessary components into this one and also make sure that you check for dependencies like DOM support right up front.
Adding the components
The other thing to add to this main object is a components object, which defines all the components that are there and their file names.
var myAwesomeApp = {
components :{
formcheck:{
url:'formcheck.js',
loaded:false
},
dynamicnav:{
url:'dynamicnav.js',
loaded:false
},
gallery:{
url:'gallery.js',
loaded:false
},
lightbox:{
url:'lightbox.js',
loaded:false
}
}
};
Technically you can also omit the loaded properties, but it is cleaner this way. The next thing to add is an addComponent function that can load your components on demand by adding new SCRIPT elements to the head of the documents when they are needed.
var myAwesomeApp = {
components :{
formcheck:{
url:'formcheck.js',
loaded:false
},
dynamicnav:{
url:'dynamicnav.js',
loaded:false
},
gallery:{
url:'gallery.js',
loaded:false
},
lightbox:{
url:'lightbox.js',
loaded:false
}
},
addComponent:function(component){
var c = this.components[component];
if(c && c.loaded === false){
var s = document.createElement('script');
s.setAttribute('type', 'text/javascript');
s.setAttribute('src',c.url);
document.getElementsByTagName('head')[0].appendChild(s);
}
}
};
This allows you to add new components on the fly when they are not defined:
if(!myAwesomeApp.components.gallery.loaded){
myAwesomeApp.addComponent('gallery');
};
Verifying that components have been loaded
However, this is not safe as the file might not be available. To make the dynamic adding of components safer each of the components should have a callback at the end of them that notifies the main object that they indeed have been loaded:
var myAwesomeApp = {
components :{
formcheck:{
url:'formcheck.js',
loaded:false
},
dynamicnav:{
url:'dynamicnav.js',
loaded:false
},
gallery:{
url:'gallery.js',
loaded:false
},
lightbox:{
url:'lightbox.js',
loaded:false
}
},
addComponent:function(component){
var c = this.components[component];
if(c && c.loaded === false){
var s = document.createElement('script');
s.setAttribute('type', 'text/javascript');
s.setAttribute('src',c.url);
document.getElementsByTagName('head')[0].appendChild(s);
}
},
componentAvailable:function(component){
this.components[component].loaded = true;
}
}
For example the gallery.js file should call this notification as a last line:
myAwesomeApp.gallery = function(){
// [... other code ...]
}();
myAwesomeApp.componentAvailable('gallery');
Telling the implementers when components are available
The last thing to add (actually as a courtesy measure for debugging and implementers) is to offer a listener function that gets notified when the component has been loaded:
var myAwesomeApp = {
components :{
formcheck:{
url:'formcheck.js',
loaded:false
},
dynamicnav:{
url:'dynamicnav.js',
loaded:false
},
gallery:{
url:'gallery.js',
loaded:false
},
lightbox:{
url:'lightbox.js',
loaded:false
}
},
addComponent:function(component){
var c = this.components[component];
if(c && c.loaded === false){
var s = document.createElement('script');
s.setAttribute('type', 'text/javascript');
s.setAttribute('src',c.url);
document.getElementsByTagName('head')[0].appendChild(s);
}
},
componentAvailable:function(component){
this.components[component].loaded = true;
if(this.listener){
this.listener(component);
};
}
};
This allows you to write a main listener function that acts when certain components have been loaded, for example:
myAwesomeApp.listener = function(component){
if(component === 'gallery'){
showGallery();
}
};
Extending with other components
As the main object is public, other developers can extend the components object with own components and use the listener function to load dependent components. Say you have a bespoke component with data and labels in extra files:
myAwesomeApp.listener = function(component){
if(component === 'bespokecomponent'){
myAwesomeApp.addComponent('bespokelabels');
};
if(component === 'bespokelabels'){
myAwesomeApp.addComponent('bespokedata');
};
if(component === 'bespokedata'){
myAwesomeApp,bespokecomponent.init();
};
};
myAwesomeApp.components.bespokecomponent = {
url:'bespoke.js',
loaded:false
};
myAwesomeApp.components.bespokelabels = {
url:'bespokelabels.js',
loaded:false
};
myAwesomeApp.components.bespokedata = {
url:'bespokedata.js',
loaded:false
};
myAwesomeApp.addComponent('bespokecomponent');
Following this practice you can write pretty complex apps and still have full control over what is available when. You can also extend this to allow for CSS files to be added on demand.
Influences
If you like this idea and wondered if someone already uses it, take a look at the Yahoo! User Interface library, and especially at the YAHOO_config option of the global YAHOO.js object. |
2007 |
Christian Heilmann |
chrisheilmann |
2007-12-18T00:00:00+00:00 |
https://24ways.org/2007/keeping-javascript-dependencies-at-bay/ |
code |
| 21 |
Keeping Parts of Your Codebase Private on GitHub |
Open source is brilliant, there’s no denying that, and GitHub has been instrumental in open source’s recent success. I’m a keen open-sourcerer myself, and I have a number of projects on GitHub. However, as great as sharing code is, we often want to keep some projects to ourselves. To this end, GitHub created private repositories which act like any other Git repository, only, well, private!
A slightly less common issue, and one I’ve come up against myself, is the desire to only keep certain parts of a codebase private. A great example would be my site, CSS Wizardry; I want the code to be open source so that people can poke through and learn from it, but I want to keep any draft blog posts private until they are ready to go live. Thankfully, there is a very simple solution to this particular problem: using multiple remotes.
Before we begin, it’s worth noting that you can actually build a GitHub Pages site from a private repo. You can keep the entire source private, but still have GitHub build and display a full Pages/Jekyll site. I do this with csswizardry.net. This post will deal with the more specific problem of keeping only certain parts of the codebase (branches) private, and expose parts of it as either an open source project, or a built GitHub Pages site.
N.B. This post requires some basic Git knowledge.
Adding your public remote
Let’s assume you’re starting from scratch and you currently have no repos set up for your project. (If you do already have your public repo set up, skip to the “Adding your private remote” section.)
So, we have a clean slate: nothing has been set up yet, we’re doing all of that now. On GitHub, create two repositories. For the sake of this article we shall call them site.com and private.site.com. Make the site.com repo public, and the private.site.com repo private (you will need a paid GitHub account).
On your machine, create the site.com directory, in which your project will live. Do your initial work in there, commit some stuff — whatever you need to do. Now we need to link this local Git repo on your machine with the public repo (remote) on GitHub. We should all be used to this:
$ git remote add origin git@github.com:[user]/site.com.git
Here we are simply telling Git to add a remote called origin which lives at git@github.com:[user]/site.com.git. Simple stuff. Now we need to push our current branch (which will be master, unless you’ve explicitly changed it) to that remote:
$ git push -u origin master
Here we are telling Git to push our master branch to a corresponding master branch on the remote called origin, which we just added. The -u sets upstream tracking, which basically tells Git to always shuttle code on this branch between the local master branch and the master branch on the origin remote. Without upstream tracking, you would have to tell Git where to push code to (and pull it from) every time you ran the push or pull commands. This sets up a permanent bond, if you like.
This is really simple stuff, stuff that you will probably have done a hundred times before as a Git user. Now to set up our private remote.
Adding your private remote
We’ve set up our public, open source repository on GitHub, and linked that to the repository on our machine. All of this code will be publicly viewable on GitHub.com. (Remember, GitHub is just a host of regular Git repositories, which also puts a nice GUI around it all.) We want to add the ability to keep certain parts of the codebase private. What we do now is add another remote repository to the same local repository. We have two repos on GitHub (site.com and private.site.com), but only one repository (and, therefore, one directory) on our machine. Two GitHub repos, and one local one.
In your local repo, check out a new branch. For the sake of this article we shall call the branch dev. This branch might contain work in progress, or draft blog posts, or anything you don’t want to be made publicly viewable on GitHub.com. The contents of this branch will, in a moment, live in our private repository.
$ git checkout -b dev
We have now made a new branch called dev off the branch we were on last (master, unless you renamed it).
Now we need to add our private remote (private.site.com) so that, in a second, we can send this branch to that remote:
$ git remote add private git@github.com:[user]/private.site.com.git
Like before, we are just telling Git to add a new remote to this repo, only this time we’ve called it private and it lives at git@github.com:[user]/private.site.com.git. We now have one local repo on our machine which has two remote repositories associated with it.
Now we need to tell our dev branch to push to our private remote:
$ git push -u private dev
Here, as before, we are pushing some code to a repo. We are saying that we want to push the dev branch to the private remote, and, once again, we’ve set up upstream tracking. This means that, by default, the dev branch will only push and pull to and from the private remote (unless you ever explicitly state otherwise).
Now you have two branches (master and dev respectively) that push to two remotes (origin and private respectively) which are public and private respectively.
Any work we do on the master branch will push and pull to and from our publicly viewable remote, and any code on the dev branch will push and pull from our private, hidden remote.
Adding more branches
So far we’ve only looked at two branches pushing to two remotes, but this workflow can grow as much or as little as you’d like. Of course, you’d never do all your work in only two branches, so you might want to push any number of them to either your public or private remotes. Let’s imagine we want to create a branch to try something out real quickly:
$ git checkout -b test
Now, when we come to push this branch, we can choose which remote we send it to:
$ git push -u private test
This pushes the new test branch to our private remote (again, setting the persistent tracking with -u).
You can have as many or as few remotes or branches as you like.
Combining the two
Let’s say you’ve been working on a new feature in private for a few days, and you’ve kept that on the private remote. You’ve now finalised the addition and want to move it into your public repo. This is just a simple merge. Check out your master branch:
$ git checkout master
Then merge in the branch that contained the feature:
$ git merge dev
Now master contains the commits that were made on dev and, once you’ve pushed master to its remote, those commits will be viewable publicly on GitHub:
$ git push
Note that we can just run $ git push on the master branch as we’d previously set up our upstream tracking (-u).
Multiple machines
So far this has covered working on just one machine; we had two GitHub remotes and one local repository. Let’s say you’ve got yourself a new Mac (yay!) and you want to clone an existing project:
$ git clone git@github.com:[user]/site.com.git
This will not clone any information about the remotes you had set up on the previous machine. Here you have a fresh clone of the public project and you will need to add the private remote to it again, as above.
Done!
If you’d like to see me blitz through all that in one go, check the showterm recording.
The beauty of this is that we can still share our code, but we don’t have to develop quite so openly all of the time. Building a framework with a killer new feature? Keep it in a private branch until it’s ready for merge. Have a blog post in a Jekyll site that you’re not ready to make live? Keep it in a private drafts branch. Working on a new feature for your personal site? Tuck it away until it’s finished. Need a staging area for a Pages-powered site? Make a staging remote with its own custom domain.
All this boils down to, really, is the fact that you can bring multiple remotes together into one local codebase on your machine. What you do with them is entirely up to you! |
2013 |
Harry Roberts |
harryroberts |
2013-12-09T00:00:00+00:00 |
https://24ways.org/2013/keeping-parts-of-your-codebase-private-on-github/ |
code |
| 129 |
Knockout Type - Thin Is Always In |
OS X has gorgeous native anti-aliasing (although I will admit to missing 10px aliased Geneva — *sigh*). This is especially true for dark text on a light background. However, things can go awry when you start using light text on a dark background. Strokes thicken. Counters constrict. Letterforms fill out like seasonal snackers.
So how do we combat the fat? In Safari and other Webkit-based browsers we can use the CSS ‘text-shadow’ property. While trying to add a touch more contrast to the navigation on haveamint.com I noticed an interesting side-effect on the weight of the type.
The second line in the example image above has the following style applied to it:
This creates an invisible drop-shadow. (Why is it invisible? The shadow is positioned directly behind the type (the first two zeros) and has no spread (the third zero). So the color, black, is completely eclipsed by the type it is supposed to be shadowing.)
Why applying an invisible drop-shadow effectively lightens the weight of the type is unclear. What is clear is that our light-on-dark text is now of a comparable weight to its dark-on-light counterpart.
You can see this trick in effect all over ShaunInman.com and in the navigation on haveamint.com and Subtraction.com. The HTML and CSS source code used to create the example images used in this article can be found here. |
2006 |
Shaun Inman |
shauninman |
2006-12-17T00:00:00+00:00 |
https://24ways.org/2006/knockout-type/ |
code |
| 195 |
Levelling Up for Junior Developers |
If you are a junior developer starting out in the web industry, things can often seem a little daunting. There are so many things to learn, and as soon as you’ve learnt one framework or tool, there seems to be something new out there.
I am lucky enough to lead a team of developers building applications for the web. During a recent One to One meeting with one of our junior developers, he asked me about a learning path and the basic fundamentals that every developer should know. After a bit of digging around, I managed to come up with a (not so exhaustive) list of principles that was shared with him.
In this article, I will share the list with you, and hopefully help you level up from junior developer and become a better developer all round. This list doesn’t focus on an particular programming language, but rather coding concepts as a whole. The idea behind this list is that whether you are a front-end developer, back-end developer, full stack developer or just a curious one, these principles apply to everyone that writes code.
I have tried to be technology agnostic, so that you can use these tips to guide you, whatever your tech stack might be.
Without any further ado and in no particular order, let’s get started.
Refactoring code like a boss
The Boy Scouts have a rule that goes “always leave the campground cleaner than you found it.” This rule can be applied to code too and ensures that you leave code cleaner than you found it. As a junior developer, it’s almost certain that you will either create or come across older code that could be improved. The resources below are a guide that will help point you in the right direction.
My favourite book on this subject has to be Clean Code by Robert C. Martin. It’s a must read for anyone writing code as it helps you identify bad code and shows you techniques that you can use to improve existing code.
If you find that in your day to day work you deal with a lot of legacy code, Improving Existing Technology through Refactoring is another useful read.
Design Patterns are a general repeatable solution to a commonly occurring problem in software design. My friend and colleague Ranj Abass likes to refer to them as a “common language” that helps developers discuss the way that we write code as a pattern. My favourite book on this subject is Head First Design Patterns which goes right back to the basics. Another great read on this topic is Refactoring to Patterns.
Working Effectively With Legacy Code is another one that I found really valuable.
Improving your debugging skills
A solid understanding of how to debug code is a must for any developer. Whether you write code for the web or purely back-end code, the ability to debug will save you time and help you really understand what is going on under the hood.
If you write front-end code for the web, one of my favourite resources to help you understand how to debug code in Chrome can be found on the Chrome Dev Tools website. While some of the tips are specific to Chrome, these techniques apply to any modern browser of your choice.
At Settled, we use Node.js for much of our server side code. Without a doubt, our most trusted IDE has to be Visual Studio Code and the built-in debuggers are amazing. Regardless of whether you use Node.js or not, there are a number of plugins and debuggers that you can use in the IDE. I recommend reading the website of your favourite IDE for more information.
As a side note, it is worth mentioning that Chrome Developer Tools actually has functionality that allows you to debug Node.js code too. This makes it a seamless transition from front-end code to server-side code debugging.
The Debugging Mindset is an informative online article by Devon H. O’Dell and discusses the the psychology of learning strategies that lead to effective problem-solving skills.
A good understanding of relational databases and NoSQL databases
Almost all developers will need to persist data at some point in their career. Even if you don’t write SQL queries in your day to day job, a solid understanding of how they work will help you become a better developer.
If you are a complete newbie when it comes to databases, I recommend checking out Code Academy. They offer a free online course that can help you get your head around how relational databases work. The course is quite basic, but is a useful hands-on approach to learning this topic.
This article provides a great explainer for the difference between the SQL and NoSQL databases, and this Stackoverflow answer goes a little deeper into the subject of the two database types.
If you’d like to learn more about NoSQL queries, I would recommend starting with this article on MongoDB queries. Unfortunately, there isn’t one overall course as most NoSQL databases have their own syntax.
You may also have noticed that I haven’t included other types of databases such as Graph or In-memory; it’s worth focussing on the basics before going any deeper.
Performance on the web
If you build for the web today, it is important to understand how the browser receives and renders the content that you send it. I am pretty passionate about Web Performance, and hope that everyone can learn how to make websites faster and more efficient. It can be fun at the same time!
Steve Souders High Performance Websites is the godfather of web performance books. While it was created a few years ago and many of the techniques might have changed slightly, it is the original book on the subject and set up many of the ground rules that we know about web performance today.
A free online resource on this topic is the Google Developers website. The site is an up to date guide on the best web performance techniques for your site. It is definitely worth a read.
The network plays a key role in delivering data to your users, and it plays a big role in performance on the web. A fantastic book on this topic is Ilya Grigorik’s High Performance Browser Networking. It is also available to read online at hpbn.co.
Understand the end to end architecture of your software project
I find that one of the best ways to improve my knowledge is to learn about the architecture of the software at the company I work at. It gives you a good understanding as to why things are designed the way they are, why certain decisions were made, and gives you an understanding of how you might do things differently with hindsight.
Try and find someone more senior, such as a Technical Lead or Software Architect, at your company and ask them to explain the overall architecture and draw a few high-level diagrams for you. Not to mention that they will be impressed with your willingness to learn.
I recommend reading Clean Architecture: A Craftsman’s Guide to Software Structure and Design for more detail on this subject.
Far too often, software projects can be over-engineered and over-architected, it is worth reading Just Enough Software Architecture. The book helps developers understand how the smallest of changes can affect the outcome of your software architecture.
How are things deployed
A big part of creating software is actually shipping it! How is the software at your company released into the wild? Does your company do Continuous Integration? Continuous Deployment?
Even if you answered no to any of these questions, it is worth finding someone with the knowledge in your company to explain these things to you. If it is not already documented, perhaps you could start a wiki to document everything you’re learning about the system - this is a great way to level up and be appreciated and invaluable.
A streamlined deployment process is a beautiful thing, and understanding how they work can help you grow your knowledge as a developer.
Continuous Integration is a practical read on the ins and outs of implementing this deployment technique.
Docker is another great tool to use when it comes to software deployment. It can be tricky at first to wrap your head around, but it is definitely worth learning about this great technology. The documentation on the website will teach and guide you on how to get started using Docker.
Writing Tests
Testing is an essential tool in the developer bag of skills. They help you to make big refactoring changes to your code, and feel a lot more confident knowing that your changes haven’t broken anything. There are so many benefits to testing, which make it so important for developers at every level to become acquainted with it/them.
The book that started it all for me was Roy Osherove’s The Art of Unit Testing. The code in the book is written in C#, but the principles apply to every language. It’s a great, easy-to-understand read.
Another great read is How Google Tests Software and covers exactly what it says on the tin. It covers many different testing techniques such as exploratory, black box, white box, and acceptance testing and really helps you understand how large organisations test their code.
Soft skills
Whilst reading through this article, you’ve probably noticed that a large chunk of it focusses on code and technical ability. Without a doubt, I’d say that it is even more important to be a good teammate. If you look up the definition of soft skills in the dictionary, it is defined as “personal attributes that enable someone to interact effectively and harmoniously with other people” and I think that it sums this up perfectly. Working on your “soft skills” is something that can truly help you level up in your career. You may be the world’s greatest coder, but if you colleagues can’t get along with you, your coding skills won’t matter!
While you may not learn how to become the perfect co-worker overnight, I really try and live by the motto “don’t be an arsehole”. Think about how you like to be treated and then try and treat your co-workers with the same courtesy and respect. The next time you need to make a decision at work, ask yourself “is this something an arsehole would do”? If you answered yes to that question, you probably shouldn’t do it!
Summary
Levelling up as a junior developer doesn’t have to be scary. Focus on the fundamentals and they should hold you in good stead, regardless of the new things that come along. Software engineering is built on these great principles that have stood the test of time.
Whilst researching for this article, I came across a useful Github repo that is worth mentioning. Things Every Programmer Should Know is packed with useful information. I have to admit, I didn’t know everything on there!
I hope that you have found this list helpful. Some of the topics I have mentioned might not be relevant for you at this stage in your career, but should give a nudge in the right direction. After all, knowledge is power!
If you are a junior developer reading this article, what would you add to it? |
2017 |
Dean Hume |
deanhume |
2017-12-05T00:00:00+00:00 |
https://24ways.org/2017/levelling-up-for-junior-developers/ |
code |
| 201 |
Lint the Web Forward With Sonarwhal |
Years ago, when I was in a senior in college, much of my web development courses focused on two things: the basics like HTML and CSS (and boy, do I mean basic), and Adobe Flash. I spent many nights writing ActionScript 3.0 to build interactions for the websites that I would add to my portfolio. A few months after graduating, I built one website in Flash for a client, then never again. Flash was dying, and it became obsolete in my résumé and portfolio.
That was my first lesson in the speed at which things change in technology, and what a daunting realization that was as a new graduate looking to enter the professional world. Now, seven years later, I work on the Microsoft Edge team where I help design and build a tool that would have lessened my early career anxieties: sonarwhal.
Sonarwhal is a linting tool, built by and for the web community. The code is open source and lives under the JS Foundation. It helps web developers and designers like me keep up with the constant change in technology while simultaneously teaching how to code better websites.
Introducing sonarwhal’s mascot Nellie
Good web development is hard. It is more than HTML, CSS, and JavaScript: developers are expected to have a grasp of accessibility, performance, security, emerging standards, and more, all while refreshing this knowledge every few months as the web evolves. It’s a lot to keep track of.
Web development is hard
Staying up-to-date on all this knowledge is one of the driving forces for developing this scanning tool. Whether you are just starting out, are a student, or you have over a decade of experience, the sonarwhal team wants to help you build better websites for all browsers.
Currently sonarwhal checks for best practices in five categories: Accessibility, Interoperability, Performance, PWAs, and Security. Each check is called a “rule”. You can configure them and even create your own rules if you need to follow some specific guidelines for your project (e.g. validate analytics attributes, title format of pages, etc.).
You can use sonarwhal in two ways:
An online version, that provides a quick and easy way to scan any public website.
A command line tool, if you want more control over the configuration, or want to integrate it into your development flow.
The Online Scanner
The online version offers a streamlined way to scan a website; just enter a URL and you will get a web page of scan results with a permalink that you can share and revisit at any time.
The online version of sonarwal
When my team works on a new rule, we spend the bulk of our time carefully researching each subject, finding sources, and documenting it rather than writing the rule’s code. Not only is it important that we get you the right results, but we also want you to understand why something is failing. Next to each failing rule you’ll find a link to its detailed documentation, explaining why you should care about it, what exactly we are testing, examples that pass and examples that don’t, and useful links to even more in-depth documentation if you are interested in the subject.
We hope that between reading the documentation and continued use of sonarwhal, developers can stay on top of best practices. As devs continue to build sites and identify recurring issues that appear in their results, they will hopefully start to automatically include those missing elements or fix those pieces of code that are producing errors. This also isn’t a one-way communication: the documentation is not only available on the sonarwhal site, but also on GitHub for editing so you can help us make it even better!
A results report
The current configuration for the online scanner is very strict, so it might hurt your feelings (it did when I first tested it on my personal website). But you can configure sonarwhal to any level of strictness as well as customize the command line tool to your needs!
Sonarwhal’s CLI
The CLI gives you full control of sonarwhal: what rules to use, tweaks to them, domains that are out of your control, and so on. You will need the latest node LTS (v8) or Stable (v9) and your favorite package manager, such as npm:
npm install -g sonarwhal
You can now run sonarwhal from anywhere via:
sonarwhal https://example.com
Using the CLI
The configuration is done via a .sonarwhalrc file. When analyzing a site, if no file is available, you will be prompted to answer a series of questions:
What connector do you want to use? Connectors are what sonarwhal uses to access a website and gather all the information about the requests, resources, HTML, etc. Currently it supports jsdom, Microsoft Edge, and Google Chrome.
What formatter? This is how you want to see the results: summary, stylish, etc. Make sure to look at the full list. Some are concise for, perfect for a quick build assessment, while others are more verbose and informative.
Do you want to use the recommended rules configuration? Rules are the things we are validating. Unless you’ve read the documentation and know what you are doing, first timers should probably use the recommended configuration.
What browsers are you targeting? One of the best features of sonarwhal is that rules can adapt their feedback depending on your targeted browsers, suggesting to add or remove things. For example, the rule “Highest Document Mode” will tell you to add the “X-UA-Compatible” header if IE10 or lower is targeted or remove if the opposite is true.
sonarwhal configuration generator questions
Once you answer all these questions the scan will start and you will have a .sonarwhalrc file similar to the following:
{
"connector": {
"name": "jsdom",
"options": {
"waitFor": 1000
}
},
"formatters": "stylish",
"rulesTimeout": 120000,
"rules": {
"apple-touch-icons": "error",
"axe": "error",
"content-type": "error",
"disown-opener": "error",
"highest-available-document-mode": "error",
"validate-set-cookie-header": "warning",
// ...
}
}
You should see the scan initiate in the command line and within a few seconds the results should start to appear. Remember, the scan results will look different depending on which formatter you selected so try each one out to see which one you like best.
sonarwhal results on my website and hurting my feelings 💔
Now that you have a list of errors, you can get to work improving the site! Note though, that when you scan your website, it scans all the resources on that page and if you’ve added something like analytics or fonts hosted elsewhere, you are unable to change those files. You can configure the CLI to ignore files from certain domains so that you are only getting results for files you are in control of.
The documentation should give enough guidance on how to fix the errors, but if it’s insufficient, please help us and suggest edits or contribute back to it. This is a community effort and chances are someone else will have the same question as you.
When I scanned both my websites, sonarwhal alerted me to not having an Apple Touch Icon. If I search on the web as opposed to using the sonarwhal documentation, the first top 3 results give me outdated information: I need to include many different icon sizes. I don’t need to include all the different size icons that target different devices. Declaring one icon sized 180px x 180px will provide a large enough icon for devices and it will scale down as appropriate for people on older devices.
The information at the top of the search results isn’t always the correct answer to an issue and we don’t want you to have to search through outdated documentation. As sonarwhal’s capabilities expand, the goal is for it to be the one stop shop for helping preflight your website.
The journey up until now and looking forward
On the Microsoft Edge team, we’re passionate about empowering developers to build great websites. Every day we see so many sites come through our issue tracker. (Thanks for filing those bugs, they help us make Microsoft Edge better and better!) Some issues we see over and over are honest mistakes or outdated ‘best practices’ that could be avoided, so we built this tool to help everyone help make the web a better place.
When we decided to create sonarwhal, we wanted to create a tool that would help developers write better and more up-to-date code for their websites. We want sonarwhal to be useful to anyone so, early on, we defined three guiding principles we’ve used along the way:
Community Driven. We build for the community’s best interests. The web belongs to everyone and this project should too. Not only is it open source, we’ve also donated it to the JS Foundation and have an inclusive governance model that welcomes the collaboration of anyone, individual or company.
User Centric. We want to put the user at the center, making sonarwhal configurable for your needs and easy to use no matter what your skill level is.
Collaborative. We didn’t want to reinvent the wheel, so we collaborated with existing tools and services that help developers build for the web. Some examples are aXe, snyk.io, Cloudinary, etc.
This is just the beginning and we still have lots to do. We’re hard at work on a backlog of exciting features for future releases, such as:
New rules for a variety of areas like performance, accessibility, security, progressive web apps, and more.
A plug-in for Visual Studio Code: we want sonarwhal to help you write better websites, and what better moment than when you are in your editor.
Configuration options for the online service: as we fine tune the infrastructure, the rule configuration for our scanner is locked, but we look forward to adding CLI customization options here in the near future.
This is a tool for the web community by the web community so if you are excited about sonarwhal, making a better web, and want to contribute, we have a few issues where you might be able to help. Also, don’t forget to check the rest of the sonarwhal GitHub organization. PRs are always welcome and appreciated!
Let us know what you think about the scanner at @NarwhalNellie on Twitter and we hope you’ll help us lint the web forward! |
2017 |
Stephanie Drescher |
stephaniedrescher |
2017-12-02T00:00:00+00:00 |
https://24ways.org/2017/lint-the-web-forward-with-sonarwhal/ |
code |
| 20 |
Make Your Browser Dance |
It was a crisp winter’s evening when I pulled up alongside the pier. I stepped out of my car and the bitterly cold sea air hit my face. I walked around to the boot, opened it and heaved out a heavy flight case. I slammed the boot shut, locked the car and started walking towards the venue.
This was it. My first gig. I thought about all those weeks of preparation: editing video clips, creating 3-D objects, making coloured patterns, then importing them all into software and configuring effects to change as the music did; targeting frequency, beat, velocity, modifying size, colour, starting point; creating playlists of these… and working out ways to mix them as the music played.
This was it. This was me VJing.
This was all a lifetime (well a decade!) ago.
When I started web designing, VJing took a back seat. I was more interested in interactive layouts, semantic accessible HTML, learning all the IE bugs and mastering the quirks that CSS has to offer. More recently, I have been excited by background gradients, 3-D transforms, the @keyframe directive, as well as new APIs such as getUserMedia, indexedDB, the Web Audio API
But wait, have I just come full circle? Could it be possible, with these wonderful new things in technologies I am already familiar with, that I could VJ again, right here, in a browser?
Well, there’s only one thing to do: let’s try it!
Let’s take to the dance floor
Over the past couple of years working in The Lab I have learned to take a much more iterative approach to projects than before. One of my new favourite methods of working is to create a proof of concept to make sure my theory is feasible, before going on to create a full-blown product. So let’s take the same approach here.
The main VJing functionality I want to recreate is manipulating visuals in relation to sound. So for my POC I need to create a visual, with parameters that can be changed, then get some sound and see if I can analyse that sound to detect some data, which I can then use to manipulate the visual parameters. Easy, right?
So, let’s start at the beginning: creating a simple visual. For this I’m going to create a CSS animation. It’s just a funky i element with the opacity being changed to make it flash.
See the Pen Creating a light by Rumyra (@Rumyra) on CodePen
A note about prefixes: I’ve left them out of the code examples in this post to make them easier to read. Please be aware that you may need them. I find a great resource to find out if you do is caniuse.com. You can also check out all the code for the examples in this article
Start the music
Well, that’s pretty easy so far. Next up: loading in some sound. For this we’ll use the Web Audio API. The Web Audio API is based around the concept of nodes. You have a source node: the sound you are loading in; a destination node: usually the device’s speakers; and any number of processing nodes in between. All this processing that goes on with the audio is sandboxed within the AudioContext.
So, let’s start by initialising our audio context.
var contextClass = window.AudioContext;
if (contextClass) {
//web audio api available.
var audioContext = new contextClass();
} else {
//web audio api unavailable
//warn user to upgrade/change browser
}
Now let’s load our sound file into the new context we created with an XMLHttpRequest.
function loadSound() {
//set audio file url
var audioFileUrl = '/octave.ogg';
//create new request
var request = new XMLHttpRequest();
request.open("GET", audioFileUrl, true);
request.responseType = "arraybuffer";
request.onload = function() {
//take from http request and decode into buffer
context.decodeAudioData(request.response, function(buffer) {
audioBuffer = buffer;
});
}
request.send();
}
Phew! Now we’ve loaded in some sound! There are plenty of things we can do with the Web Audio API: increase volume; add filters; spatialisation. If you want to dig deeper, the O’Reilly Web Audio API book by Boris Smus is available to read online free.
All we really want to do for this proof of concept, however, is analyse the sound data. To do this we really need to know what data we have.
Learning the steps
Let’s take a minute to step back and remember our school days and science class. I’m sure if I drew a picture of a sound wave, we would all start nodding our heads.
The sound you hear is caused by pressure differences in the particles in the air. Sound pushes these particles together, causing vibrations. Amplitude is basically strength of pressure. A simple example of change of amplitude is when you increase the volume on your stereo and the output wave increases in size.
This is great when everything is analogue, but the waveform varies continuously and it’s not suitable for digital processing: there’s an infinite set of values. For digital processing, we need discrete numbers.
We have to sample the waveform at set time intervals, and record data such as amplitude and frequency. Luckily for us, just the fact we have a digital sound file means all this hard work is done for us. What we’re doing in the code above is piping that data in the audio context. All we need to do now is access it.
We can do this with the Web Audio API’s analysing functionality. Just pop in an analysing node before we connect the source to its destination node.
function createAnalyser(source) {
//create analyser node
analyser = audioContext.createAnalyser();
//connect to source
source.connect(analyzer);
//pipe to speakers
analyser.connect(audioContext.destination);
}
The data I’m really interested in here is frequency. Later we could look into amplitude or time, but for now I’m going to stick with frequency.
The analyser node gives us frequency data via the getFrequencyByteData method.
Don’t forget to count!
To collect the data from the getFrequencyByteData method, we need to pass in an empty array (a JavaScript typed array is ideal). But how do we know how many items the array will need when we create it?
This is really up to us and how high the resolution of frequencies we want to analyse is. Remember we talked about sampling the waveform; this happens at a certain rate (sample rate) which you can find out via the audio context’s sampleRate attribute. This is good to bear in mind when you’re thinking about your resolution of frequencies.
var sampleRate = audioContext.sampleRate;
Let’s say your file sample rate is 48,000, making the maximum frequency in the file 24,000Hz (thanks to a wonderful theorem from Dr Harry Nyquist, the maximum frequency in the file is always half the sample rate). The analyser array we’re creating will contain frequencies up to this point. This is ideal as the human ear hears the range 0–20,000hz.
So, if we create an array which has 2,400 items, each frequency recorded will be 10Hz apart. However, we are going to create an array which is half the size of the FFT (fast Fourier transform), which in this case is 2,048 which is the default. You can set it via the fftSize property.
//set our FFT size
analyzer.fftSize = 2048;
//create an empty array with 1024 items
var frequencyData = new Uint8Array(1024);
So, with an array of 1,024 items, and a frequency range of 24,000Hz, we know each item is 24,000 ÷ 1,024 = 23.44Hz apart.
The thing is, we also want that array to be updated constantly. We could use the setInterval or setTimeout methods for this; however, I prefer the new and shiny requestAnimationFrame.
function update() {
//constantly getting feedback from data
requestAnimationFrame(update);
analyzer.getByteFrequencyData(frequencyData);
}
Putting it all together
Sweet sticks! Now we have an array of frequencies from the sound we loaded, updating as the sound plays. Now we want that data to trigger our animation from earlier.
We can easily pause and run our CSS animation from JavaScript:
element.style.webkitAnimationPlayState = "paused";
element.style.webkitAnimationPlayState = "running";
Unfortunately, this may not be ideal as our animation might be a whole heap longer than just a flashing light. We may want to target specific points within that animation to have it stop and start in a visually pleasing way and perhaps not smack bang in the middle.
There is no really easy way to do this at the moment as Zach Saucier explains in this wonderful article. It takes some jiggery pokery with setInterval to try to ascertain how far through the CSS animation you are in percentage terms.
This seems a bit much for our proof of concept, so let’s backtrack a little. We know by the animation we’ve created which CSS properties we want to change. This is pretty easy to do directly with JavaScript.
element.style.opacity = "1";
element.style.opacity = "0.2";
So let’s start putting it all together. For this example I want to trigger each light as a different frequency plays. For this, I’ll loop through the HTML elements and change the opacity style if the frequency gain goes over a certain threshold.
//get light elements
var lights = document.getElementsByTagName('i');
var totalLights = lights.length;
for (var i=0; i<totalLights; i++) {
//get frequencyData key
var freqDataKey = i*8;
//if gain is over threshold for that frequency animate light
if (frequencyData[freqDataKey] > 160){
//start animation on element
lights[i].style.opacity = "1";
} else {
lights[i].style.opacity = "0.2";
}
}
See all the code in action here. I suggest viewing in a modern browser :)
Awesome! It is true — we can VJ in our browser!
Let’s dance!
So, let’s start to expand this simple example. First, I feel the need to make lots of lights, rather than just a few. Also, maybe we should try a sound file more suited to gigs or clubs.
Check it out!
I don’t know about you, but I’m pretty excited — that’s just a bit of HTML, CSS and JavaScript!
The other thing to think about, of course, is the sound that you would get at a venue. We don’t want to load sound from a file, but rather pick up on what is playing in real time. The easiest way to do this, I’ve found, is to capture what my laptop’s mic is picking up and piping that back into the audio context. We can do this by using getUserMedia.
Let’s include this in this demo. If you make some noise while viewing the demo, the lights will start to flash.
And relax :)
There you have it. Sit back, play some music and enjoy the Winamp like experience in front of you.
So, where do we go from here? I already have a wealth of ideas. We haven’t started with canvas, SVG or the 3-D features of CSS. There are other things we can detect from the audio as well. And yes, OK, it’s questionable whether the browser is the best environment for this. For one, I’m using a whole bunch of nonsensical HTML elements (maybe each animation could be held within a web component in the future). But hey, it’s fun, and it looks cool and sometimes I think it’s OK to just dance. |
2013 |
Ruth John |
ruthjohn |
2013-12-02T00:00:00+00:00 |
https://24ways.org/2013/make-your-browser-dance/ |
code |
| 30 |
Making Sites More Responsive, Responsibly |
With digital projects we’re used to shifting our thinking to align with our target audience. We may undertake research, create personas, identify key tasks, or observe usage patterns, with our findings helping to refine our ongoing creations. A product’s overall experience can make or break its success, and when it comes to defining these experiences our development choices play a huge role alongside more traditional user-focused activities.
The popularisation of responsive web design is a great example of how we are able to shape the web’s direction through using technology to provide better experiences. If we think back to the move from table-based layouts to CSS, initially our clients often didn’t know or care about the difference in these approaches, but we did. Responsive design was similar in this respect – momentum grew through the web industry choosing to use an approach that we felt would give a better experience, and which was more future-friendly.
We tend to think of responsive design as a means of displaying content appropriately across a range of devices, but the technology and our implementation of it can facilitate much more. A responsive layout not only helps your content work when the newest smartphone comes out, but it also ensures your layout suitably adapts if a visually impaired user drastically changes the size of the text.
The 24 ways site at 400% on a Retina MacBook Pro displays a layout more typically used for small screens.
When we think more broadly, we realise that our technical choices and approaches to implementation can have knock-on effects for the greater good, and beyond our initial target audiences. We can make our experiences more responsive to people’s needs, enhancing their usability and accessibility along the way.
Being responsibly responsive
Of course, when we think about being more responsive, there’s a fine line between creating useful functionality and becoming intrusive and overly complex. In the excellent Responsible Responsive Design, Scott Jehl states that:
A responsible responsive design equally considers the following throughout a project:
Usability: The way a website’s user interface is presented to the user, and how that UI responds to browsing conditions and user interactions.
Access: The ability for users of all devices, browsers, and assistive technologies to access and understand a site’s features and content.
Sustainability: The ability for the technology driving a site or application to work for devices that exist today and to continue to be usable and accessible to users, devices, and browsers in the future.
Performance: The speed at which a site’s features and content are perceived to be delivered to the user and the efficiency with which they operate within the user interface.
Scott’s book covers these ideas in a lot more detail than I’ll be able to here (put it on your Christmas list if it’s not there already), but for now let’s think a bit more about our roles as digital creators and the power this gives us.
Our choices around technology and the decisions we have to make can be extremely wide-ranging. Solutions will vary hugely depending on the needs of each project, though we can further explore the concept of making our creations more responsive through the use of humble web technologies.
The power of the web
We all know that under the HTML5 umbrella are some great new capabilities, including a number of JavaScript APIs such as geolocation, web audio, the file API and many more. We often use these to enhance the functionality of our sites and apps, to add in new features, or to facilitate device-specific interactions.
You’ll have seen articles with flashy titles such as “Top 5 JavaScript APIs You’ve Never Heard Of!”, which you’ll probably read, think “That’s quite cool”, yet never use in any real work.
There is great potential for technologies like these to be misused, but there are also great prospects for them to be used well to enhance experiences. Let’s have a look at a few examples you may not have considered.
Offline first
When we make websites, many of us follow a process which involves user stories – standardised snippets of context explaining who needs what, and why.
“As a student I want to pay online for my course so I don’t have to visit the college in person.”
“As a retailer I want to generate unique product codes so I can manage my stock.”
We very often focus heavily on what needs doing, but may not consider carefully how it will be done. As in Scott’s list, accessibility is extremely important, not only in terms of providing a great experience to users of assistive technologies, but also to make your creation more accessible in the general sense – including under different conditions.
Offline first is yet another ‘first’ methodology (my personal favourite being ‘tea first’), which encourages us to develop so that connectivity itself is an enhancement – letting users continue with tasks even when they’re offline. Despite the rapid growth in public Wi-Fi, if we consider data costs and connectivity in developing countries, our travel habits with planes, underground trains and roaming (or simply if you live in the UK’s signal-barren East Anglian wilderness as I do), then you’ll realise that connectivity isn’t as ubiquitous as our internet-addled brains would make us believe. Take a scenario that I’m sure we’re all familiar with – the digital conference. Your venue may be in a city served by high-speed networks, but after overloading capacity with a full house of hashtag-hungry attendees, each carrying several devices, then everyone’s likely to be offline after all. Wouldn’t it be better if we could do something like this instead?
Someone visits our conference website.
On this initial run, some assets may be cached for future use: the conference schedule, the site’s CSS, photos of the speakers.
When the attendee revisits the site on the day, the page shell loads up from the cache.
If we have cached content (our session timetable, speaker photos or anything else), we can load it directly from the cache. We might then try to update this, or get some new content from the internet, but the conference attendee already has a base experience to use.
If we don’t have something cached already, then we can try grabbing it online.
If for any reason our requests for new content fail (we’re offline), then we can display a pre-cached error message from the initial load, perhaps providing our users with alternative suggestions from what is cached.
There are a number of ways we can make something like this, including using the application cache (AppCache) if you’re that way inclined. However, you may want to look into service workers instead. There are also some great resources on Offline First! if you’d like to find out more about this.
Building in offline functionality isn’t necessarily about starting offline first, and it’s also perfectly possible to retrofit sites and apps to catch offline scenarios, but this kind of graceful degradation can end up being more complex than if we’d considered it from the start. By treating connectivity as an enhancement, we can improve the experience and provide better performance than we can when waiting to counter failures. Our websites can respond to connectivity and usage scenarios, on top of adapting how we present our content. Thinking in this way can enhance each point in Scott’s criteria.
As I mentioned, this isn’t necessarily the kind of development choice that our clients will ask us for, but it’s one we may decide is simply the right way to build based on our project, enhancing the experience we provide to people, and making it more responsive to their situation.
Even more accessible
We’ve looked at accessibility in terms of broadening when we can interact with a website, but what about how? Our user stories and personas are often of limited use. We refer in very general terms to students, retailers, and sometimes just users. What if we have a student whose needs are very different from another student? Can we make our sites even more usable and accessible through our development choices?
Again using JavaScript to illustrate this concept, we can do a lot more with the ways people interact with our websites, and with the feedback we provide, than simply accepting keyboard, mouse and touch inputs and displaying output on a screen.
Input
Ambient light detection is one of those features that looks great in simple demos, but which we struggle to put to practical use. It’s not new – many satnav systems automatically change the contrast for driving at night or in tunnels, and our laptops may alter the screen brightness or keyboard backlighting to better adapt to our surroundings. Using web technologies we can adapt our presentation to be better suited to ambient light levels.
If our device has an appropriate light sensor and runs a browser that supports the API, we can grab the ambient light in units using ambient light events, in JavaScript. We may then change our presentation based on different bandings, perhaps like this:
window.addEventListener('devicelight', function(e) {
var lux = e.value;
if (lux < 50) {
//Change things for dim light
}
if (lux >= 50 && lux <= 10000) {
//Change things for normal light
}
if (lux > 10000) {
//Change things for bright light
}
});
Live demo (requires light sensor and supported browser).
Soon we may also be able to do such detection through CSS, with light-level being cited in the Media Queries Level 4 specification. If that becomes the case, it’ll probably look something like this:
@media (light-level: dim) {
/*Change things for dim light*/
}
@media (light-level: normal) {
/*Change things for normal light*/
}
@media (light-level: washed) {
/*Change things for bright light*/
}
While we may be quick to dismiss this kind of detection as being a gimmick, it’s important to consider that apps such as Light Detector, listed on Apple’s accessibility page, provide important context around exactly this functionality.
“If you are blind, Light Detector helps you to be more independent in many daily activities. At home, point your iPhone towards the ceiling to understand where the light fixtures are and whether they are switched on. In a room, move the device along the wall to check if there is a window and where it is. You can find out whether the shades are drawn by moving the device up and down.”
everywaretechnologies.com/apps/lightdetector
Input can be about so much more than what we enter through keyboards. Both an ever increasing amount of available sensors and more APIs being supported by the major browsers will allow us to cater for more scenarios and respond to them accordingly. This can be as complex or simple as you need; for instance, while x-webkit-speech has been deprecated, the web speech API is available for a number of browsers, and research into sign language detection is also being performed by organisations such as Microsoft.
Output
Web technologies give us some great enhancements around input, allowing us to adapt our experiences accordingly. They also provide us with some nice ways to provide feedback to users.
When we play video games, many of our modern consoles come with the ability to have rumble effects on our controller pads. These are a great example of an enhancement, as they provide a level of feedback that is entirely optional, but which can give a great deal of extra information to the player in the right circumstances, and broaden the scope of our comprehension beyond what we’re seeing and hearing.
Haptic feedback is possible on the web as well. We could use this in any number of responsible applications, such as alerting a user to changes or using different patterns as a communication mechanism. If you find yourself in a pickle, here’s how to print out SOS in Morse code through the vibration API. The following code indicates the length of vibration in milliseconds, interspersed by pauses in milliseconds.
navigator.vibrate([100, 300, 100, 300, 100, 300, 600, 300, 600, 300, 600, 300, 100, 300, 100, 300, 100]);
Live demo (requires supported browser)
With great power…
What you’ve no doubt come to realise by now is that these are just more examples of progressive enhancement, whose inclusion will provide a better experience if the capabilities are available, but which we should not rely on. This idea isn’t new, but the most important thing to remember, and what I would like you to take away from this article, is that it is up to us to decide to include these kind of approaches within our projects – if we don’t root for them, they probably won’t happen. This is where our professional responsibility comes in.
We won’t necessarily be asked to implement solutions for the scenarios above, but they illustrate how we can help to push the boundaries of experiences. Maybe we’ll have to switch our thinking about how we build, but we can create more usable products for a diverse range of people and usage scenarios through the choices we make around technology. Let’s stop thinking simply in terms of features inside a narrow view of our target users, and work out how we can extend these to cater for a wider set of situations.
When you plan your next digital project, consider the power of the web and the enhancements we can use, and try to make your projects even more responsive and responsible. |
2014 |
Sally Jenkinson |
sallyjenkinson |
2014-12-10T00:00:00+00:00 |
https://24ways.org/2014/making-sites-more-responsive-responsibly/ |
code |
| 136 |
Making XML Beautiful Again: Introducing Client-Side XSL |
Remember that first time you saw XML and got it? When you really understood what was possible and the deep meaning each element could carry? Now when you see XML, it looks ugly, especially when you navigate to a page of XML in a browser. Well, with every modern browser now supporting XSL 1.0, I’m going to show you how you can turn something as simple as an ATOM feed into a customised page using a browser, Notepad and some XSL.
What on earth is this XSL?
XSL is a family of recommendations for defining XML document transformation and presentation. It consists of three parts:
XSLT 1.0 – Extensible Stylesheet Language Transformation, a language for transforming XML
XPath 1.0 – XML Path Language, an expression language used by XSLT to access or refer to parts of an XML document. (XPath is also used by the XML Linking specification)
XSL-FO 1.0 – Extensible Stylesheet Language Formatting Objects, an XML vocabulary for specifying formatting semantics
XSL transformations are usually a one-to-one transformation, but with newer versions (XSL 1.1 and XSL 2.0) its possible to create many-to-many transformations too. So now you have an overview of XSL, on with the show…
So what do I need?
So to get going you need a browser an supports client-side XSL transformations such as Firefox, Safari, Opera or Internet Explorer. Second, you need a source XML file – for this we’re going to use an ATOM feed from Flickr.com. And lastly, you need an editor of some kind. I find Notepad++ quick for short XSLs, while I tend to use XMLSpy or Oxygen for complex XSL work.
Because we’re doing a client-side transformation, we need to modify the XML file to tell it where to find our yet-to-be-written XSL file. Take a look at the source XML file, which originates from my Flickr photos tagged sky, in ATOM format.
The top of the ATOM file now has an additional <?xml-stylesheet /> instruction, as can been seen on Line 2 below. This instructs the browser to use the XSL file to transform the document.
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<?xml-stylesheet type="text/xsl" href="flickr_transform.xsl"?>
<feed xmlns="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
Your first transformation
Your first XSL will look something like this:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
</xsl:stylesheet>
This is pretty much the starting point for most XSL files. You will notice the standard XML processing instruction at the top of the file (line 1). We then switch into XSL mode using the XSL namespace on all XSL elements (line 2). In this case, we have added namespaces for ATOM (line 4) and Dublin Core (line 5). This means the XSL can now read and understand those elements from the source XML.
After we define all the namespaces, we then move onto the xsl:output element (line 6). This enables you to define the final method of output. Here we’re specifying html, but you could equally use XML or Text, for example. The encoding attributes on each element do what they say on the tin. As with all XML, of course, we close every element including the root.
The next stage is to add a template, in this case an <xsl:template /> as can be seen below:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
<xsl:template match="/">
<html>
<head>
<title>Making XML beautiful again : Transforming ATOM</title>
</head>
<body>
<xsl:apply-templates select="/atom:feed"/>
</body>
</html>
</xsl:template>
</xsl:stylesheet>
The beautiful thing about XSL is its English syntax, if you say it out loud it tends to make sense.
The / value for the match attribute on line 8 is our first example of XPath syntax. The expression / matches any element – so this <xsl:template/> will match against any element in the document. As the first element in any XML document is the root element, this will be the one matched and processed first.
Once we get past our standard start of a HTML document, the only instruction remaining in this <xsl:template/> is to look for and match all <atom:feed/> elements using the <xsl:apply-templates/> in line 14, above.
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
<xsl:template match="/">
<xsl:apply-templates select="/atom:feed"/>
</xsl:template>
<xsl:template match="/atom:feed">
<div id="content">
<h1>
<xsl:value-of select="atom:title"/>
</h1>
<p>
<xsl:value-of select="atom:subtitle"/>
</p>
<ul id="entries">
<xsl:apply-templates select="atom:entry"/>
</ul>
</div>
</xsl:template>
</xsl:stylesheet>
This new template (line 12, above) matches <feed/> and starts to write the new HTML elements out to the output stream. The <xsl:value-of/> does exactly what you’d expect – it finds the value of the item specifed in its select attribute. With XPath you can select any element or attribute from the source XML.
The last part is a repeat of the now familiar <xsl:apply-templates/> from before, but this time we’re using it inside of a called template. Yep, XSL is full of recursion…
<xsl:template match="atom:entry">
<li class="entry">
<h2>
<a href="{atom:link/@href}">
<xsl:value-of select="atom:title"/>
</a>
</h2>
<p class="date">
(<xsl:value-of select="substring-before(atom:updated,'T')"/>)
</p>
<p class="content">
<xsl:value-of select="atom:content" disable-output-escaping="yes"/>
</p>
<xsl:apply-templates select="atom:category"/>
</li>
</xsl:template>
The <xsl:template/> which matches atom:entry (line 1) occurs every time there is a <entry/> element in the source XML file. So in total that is 20 times, this is naturally why XSLT is full of recursion. This <xsl:template/> has been matched and therefore called higher up in the document, so we can start writing list elements directly to the output stream. The first part is simply a <h2/> with a link wrapped within it (lines 3-7). We can select attributes using XPath using @.
The second part of this template selects the date, but performs a XPath string function on it. This means that we only get the date and not the time from the string (line 9). This is achieved by getting only the part of the string that exists before the T.
Regular Expressions are not part of the XPath 1.0 string functions, although XPath 2.0 does include them. Because of this, in XSL we tend to rely heavily on the available XML output.
The third part of the template (line 12) is a <xsl:value-of/> again, but this time we use an attribute of <xsl:value-of/> called disable output escaping to turn escaped characters back into XML.
The very last section is another <xsl:apply-template/> call, taking us three templates deep. Do not worry, it is not uncommon to write XSL which go 20 or more templates deep!
<xsl:template match="atom:category">
<xsl:for-each select=".">
<xsl:element name="a">
<xsl:attribute name="rel">
<xsl:text>tag</xsl:text>
</xsl:attribute>
<xsl:attribute name="href">
<xsl:value-of select="concat(@scheme, @term)"/>
</xsl:attribute>
<xsl:value-of select="@term"/>
</xsl:element>
<xsl:text> </xsl:text>
</xsl:for-each>
</xsl:template>
In our final <xsl:template/>, we see a combination of what we have done before with a couple of twists. Once we match atom:category we then count how many elements there are at that same level (line 2). The XPath . means ‘self’, so we count how many category elements are within the <entry/> element.
Following that, we start to output a link with a rel attribute of the predefined text, tag (lines 4-6). In XSL you can just type text, but results can end up with strange whitespace if you do (although there are ways to simply remove all whitespace).
The only new XPath function in this example is concat(), which simply combines what XPaths or text there might be in the brackets. We end the output for this tag with an actual tag name (line 10) and we add a space afterwards (line 12) so it won’t touch the next tag. (There are better ways to do this in XSL using the last() XPath function).
After that, we go back to the <xsl:for-each/> element again if there is another category element, otherwise we end the <xsl:for-each/> loop and end this <xsl:template/>.
A touch of style
Because we’re using recursion through our templates, you will find this is the end of the templates and the rest of the XML will be ignored by the parser. Finally, we can add our CSS to finish up. (I have created one for Flickr and another for News feeds)
<style type="text/css" media="screen">@import "flickr_overview.css?v=001";</style>
So we end up with a nice simple to understand but also quick to write XSL which can be used on ATOM Flickr feeds and ATOM News feeds. With a little playing around with XSL, you can make XML beautiful again.
All the files can be found in the zip file (14k) |
2006 |
Ian Forrester |
ianforrester |
2006-12-07T00:00:00+00:00 |
https://24ways.org/2006/beautiful-xml-with-xsl/ |
code |
| 247 |
Managing Flow and Rhythm with CSS Custom Properties |
An important part of designing user interfaces is creating consistent vertical rhythm between elements. Creating consistent, predictable space doesn’t just make your web pages and views look better, but it can also improve the scan-ability.
Browsers ship with default CSS and these styles often create consistent rhythm for flow elements out of the box. The problem is though that we often reset these styles with a reset. Elements such as <div> and <section> also have no default margin or padding associated with them.
I’ve tried all sorts of weird and wonderful techniques to find a balance between using inherited CSS while also levelling the playing field for component driven front-ends with very little success. This experimentation is how I landed on the flow utility, though and I’m going to show you how it works. Let’s dive in!
The Flow utility
With the ever-growing number of folks working with component libraries and design systems, we could benefit from a utility that creates space for us, only when it’s appropriate to do so. The problem with my previous attempts at fixing this is that the spacing values were very rigid.
That’s fine for 90% of contexts, but sometimes, it’s handy to be able to tweak the values based on the exact context of your component. This is where CSS Custom Properties come in handy.
The code
.flow {
--flow-space: 1em;
}
.flow > * + * {
margin-top: var(--flow-space);
}
What this code does is enable you to add a class of flow to an element which will then add margin-top to sibling elements within that element. We use the lobotomised owl selector to select these siblings. This approach enables an almost anonymous and automatic system which is ideal for component library based front-ends where components probably don’t have any idea what surrounds them.
The other important part of this utility is the usage of the --flow-space custom property. We define it in the .flow component and each element within it will be spaced by --flow-space, by default. The beauty about setting this as a custom property is that custom properties also participate in the cascade, so we can utilise specificity to change it if we need it. Pretty cool, right? Let’s look at some examples.
A basic example
See the Pen CSS Flow Utility: Basic implementation by Andy Bell (@hankchizljaw) on CodePen.
https://codepen.io/hankchizljaw/pen/LXqerj
What we’ve got in this example is some basic HTML content that has a class of flow on the parent article element. Because there’s a very heavy-handed reset added as a dependency, all of the content would have been squished together without the flow utility.
Because our --flow-space custom property is set to 1em, the space between elements is 1X the font size of the element in question. This means that a <h2> in this context has a calculated margin-top value of 28.8px, because it has an assigned font size of 1.8rem. If we were to globally change the --flow-space value to 1.1em for example, we’d affect everything because margin values would be calculated as 1.1X the font size.
This example looks great because using font size as the basis of rhythm works really well. What if we wanted to to tweak certain elements within this article, though?
See the Pen CSS Flow Utility: Tweaked Basic implementation by Andy Bell (@hankchizljaw) on CodePen.
https://codepen.io/hankchizljaw/pen/qQgxaY
I like lots of whitespace with my article layouts, so the 1em space isn’t going to cut it for all elements. I like to provide plenty of space between headed sections, so I increase the --flow-space in these instances:
h2 {
--flow-space: 3rem;
}
Notice also how I also switch over to using rem units? I want to make sure that these overrides are always based on the root font size. This is a personal preference of mine and you can use whatever units you want. Just be aware that it’s better for accessibility to use flexible units like em, rem and %, so that a user’s font size preferences are honoured.
A more advanced example
Although the flow utility is super useful for a plethora of contexts, it really shines when working with a few unrelated components. Instead of having to write specific layout CSS just for your particular context, you can use flow and --flow-space to create predictable and contextual space.
See the Pen CSS Flow Utility: Unrelated components by Andy Bell (@hankchizljaw) on CodePen.
https://codepen.io/hankchizljaw/pen/ZmPGyL
In this example, we’ve got ourselves a little prototype layout that features a media element, followed by a grid of features. By using flow, it was really quick and easy to generate space between those two main elements. It was also easy to create space within the components. For example, I added it to the .media__content element, so that the article’s content would space itself:
<article class="media__content flow">
...
</article>
Something to remember though: the custom properties cascade in the same way that other CSS values do, so you’ve got to keep that in mind. We’ve got a great example of that in this example where because we’ve got the flow utility on our .features component, which has a --flow-space override: the child elements of .features will inherit that value, so we’ve had to set another value on the .features__list element.
“But what about old browsers?”, I hear you cry
We’re using CSS Custom Properties that at the time of writing, have about 88% support. One thing we can do to remedy the other 12% of browsers is to set a default, traditional margin-top value of 1em, so it calculates itself based on the element’s font-size:
.flow {
--flow-space: 1em;
}
.flow > * + * {
margin-top: 1em;
margin-top: var(--flow-space);
}
Thanks to the cascading and declarative nature of CSS, we can set that default margin-top value and then immediately set it to use the custom property instead. Browsers that understand Custom Properties will automatically apply them—those that don’t will ignore them. Yay for the cascade and progressive enhancement!
Wrapping up
This tiny little utility can bring great power for when you want to consistently space elements, vertically. It also—thanks to the power of the modern web—allows us to create contextual overrides without creating modifier classes or shame CSS.
If you’ve got other methods of doing this sort of work, please let me know on Twitter. I’d love to see what you’re working on! |
2018 |
Andy Bell |
andybell |
2018-12-07T00:00:00+00:00 |
https://24ways.org/2018/managing-flow-and-rhythm-with-css-custom-properties/ |
code |
| 143 |
Marking Up a Tag Cloud |
Everyone’s doing it.
The problem is, everyone’s doing it wrong.
Harsh words, you might think. But the crimes against decent markup are legion in this area. You see, I’m something of a markup and semantics junkie. So I’m going to analyse some of the more well-known tag clouds on the internet, explain what’s wrong, and then show you one way to do it better.
del.icio.us
I think the first ever tag cloud I saw was on del.icio.us. Here’s how they mark it up.
<div class="alphacloud">
<a href="/tag/.net" class="lb s2">.net</a>
<a href="/tag/advertising" class=" s3">advertising</a>
<a href="/tag/ajax" class=" s5">ajax</a>
...
</div>
Unfortunately, that is one of the worst examples of tag cloud markup I have ever seen. The page states that a tag cloud is a list of tags where size reflects popularity. However, despite describing it in this way to the human readers, the page’s author hasn’t described it that way in the markup. It isn’t a list of tags, just a bunch of anchors in a <div>. This is also inaccessible because a screenreader will not pause between adjacent links, and in some configurations will not announce the individual links, but rather all of the tags will be read as just one link containing a whole bunch of words. Markup crime number one.
Flickr
Ah, Flickr. The darling photo sharing site of the internet, and the biggest blind spot in every standardista’s vision. Forgive it for having atrocious markup and sometimes confusing UI because it’s just so much damn fun to use. Let’s see what they do.
<p id="TagCloud">
<a href="/photos/tags/06/" style="font-size: 14px;">06</a>
<a href="/photos/tags/africa/" style="font-size: 12px;">africa</a>
<a href="/photos/tags/amsterdam/" style="font-size: 14px;">amsterdam</a>
...
</p>
Again we have a simple collection of anchors like del.icio.us, only this time in a paragraph. But rather than using a class to represent the size of the tag they use an inline style. An inline style using a pixel-based font size. That’s so far away from the goal of separating style from content, they might as well use a <font> tag. You could theoretically parse that to extract the information, but you have more work to guess what the pixel sizes represent. Markup crime number two (and extra jail time for using non-breaking spaces purely for visual spacing purposes.)
Technorati
Ah, now. Here, you’d expect something decent. After all, the Overlord of microformats and King of Semantics Tantek Çelik works there. Surely we’ll see something decent here?
<ol class="heatmap">
<li><em><em><em><em><a href="/tag/Britney+Spears">Britney Spears</a></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><a href="/tag/Bush">Bush</a></em></em></em></em></em></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><em><em><em><em><a href="/tag/Christmas">Christmas</a></em></em></em></em></em></em></em></em></em></em></em></em></em></li>
...
<li><em><em><em><em><em><em><a href="/tag/SEO">SEO</a></em></em></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><em><em><em><em><em><em><a href="/tag/Shopping">Shopping</a></em></em></em></em></em></em></em></em></em></em></em></em></em></em></em></li>
...
</ol>
Unfortunately it turns out not to be that decent, and stop calling me Shirley. It’s not exactly terrible code. It does recognise that a tag cloud is a list of links. And, since they’re in alphabetical order, that it’s an ordered list of links. That’s nice. However … fifteen nested <em> tags? FIFTEEN? That’s emphasis for you. Yes, it is parse-able, but it’s also something of a strange way of looking at emphasis. The HTML spec states that <em> is emphasis, and <strong> is for stronger emphasis. Nesting <em> tags seems counter to the idea that different tags are used for different levels of emphasis. Plus, if you had a screen reader that stressed the voice for emphasis, what would it do? Shout at you? Markup crime number three.
So what should it be?
As del.icio.us tells us, a tag cloud is a list of tags where the size that they are rendered at contains extra information. However, by hiding the extra context purely within the CSS or the HTML tags used, you are denying that context to some users. The basic assumption being made is that all users will be able to see the difference between font sizes, and this is demonstrably false.
A better way to code a tag cloud is to put the context of the cloud within the content, not the markup or CSS alone. As an example, I’m going to take some of my favourite flickr tags and put them into a cloud which communicates the relative frequency of each tag.
To start with a tag cloud in its most basic form is just a list of links. I am going to present them in alphabetical order, so I’ll use an ordered list. Into each list item I add the number of photos I have with that particular tag. The tag itself is linked to the page on flickr which contains those photos. So we end up with this first example. To display this as a traditional tag cloud, we need to alter it in a few ways:
The items need to be displayed next to each other, rather than one-per-line
The context information should be hidden from display (but not from screen readers)
The tag should link to the page of items with that tag
Displaying the items next to each other simply means setting the display of the list elements to inline. The context can be hidden by wrapping it in a <span> and then using the off-left method to hide it. And the link just means adding an anchor (with rel="tag" for some extra microformats bonus points). So, now we have a simple collection of links in our second example.
The last stage is to add the sizes. Since we already have context in our content, the size is purely for visual rendering, so we can just use classes to define the different sizes. For my example, I’ll use a range of class names from not-popular through ultra-popular, in order of smallest to largest, and then use CSS to define different font sizes. If you preferred, you could always use less verbose class names such as size1 through size6. Anyway, adding some classes and CSS gives us our final example, a semantic and more accessible tag cloud. |
2006 |
Mark Norman Francis |
marknormanfrancis |
2006-12-09T00:00:00+00:00 |
https://24ways.org/2006/marking-up-a-tag-cloud/ |
code |
| 258 |
Mistletoe Offline |
It’s that time of year, when we gather together as families to celebrate the life of the greatest person in history. This man walked the Earth long before us, but he left behind words of wisdom. Those words can guide us every single day, but they are at the forefront of our minds during this special season.
I am, of course, talking about Murphy, and the golden rule he gave unto us:
Anything that can go wrong will go wrong.
So true! I mean, that’s why we make sure we’ve got nice 404 pages. It’s not that we want people to ever get served a File Not Found message, but we acknowledge that, despite our best efforts, it’s bound to happen sometime. Murphy’s Law, innit?
But there are some Murphyesque situations where even your lovingly crafted 404 page won’t help. What if your web server is down? What if someone is trying to reach your site but they lose their internet connection? These are all things than can—and will—go wrong.
I guess there’s nothing we can do about those particular situations, right?
Wrong!
A service worker is a Murphy-battling technology that you can inject into a visitor’s device from your website. Once it’s installed, it can intercept any requests made to your domain. If anything goes wrong with a request—as is inevitable—you can provide instructions for the browser. That’s your opportunity to turn those server outage frowns upside down. Take those network connection lemons and make network connection lemonade.
If you’ve got a custom 404 page, why not make a custom offline page too?
Get your server in order
Step one is to make …actually, wait. There’s a step before that. Step zero. Get your site running on HTTPS, if it isn’t already. You won’t be able to use a service worker unless everything’s being served over HTTPS, which makes sense when you consider the awesome power that a service worker wields.
If you’re developing locally, service workers will work fine for localhost, even without HTTPS. But for a live site, HTTPS is a must.
Make an offline page
Alright, assuming your site is being served over HTTPS, then step one is to create an offline page. Make it as serious or as quirky as is appropriate for your particular brand. If the website is for a restaurant, maybe you could put the telephone number and address of the restaurant on the custom offline page (unsolicited advice: you could also put this on the home page, you know). Here’s an example of the custom offline page for this year’s Ampersand conference.
When you’re done, publish the offline page at suitably imaginative URL, like, say /offline.html.
Pre-cache your offline page
Now create a JavaScript file called serviceworker.js. This is the script that the browser will look to when certain events are triggered. The first event to handle is what to do when the service worker is installed on the user’s device. When that happens, an event called install is fired. You can listen out for this event using addEventListener:
addEventListener('install', installEvent => {
// put your instructions here.
}); // end addEventListener
In this case, you want to make sure that your lovingly crafted custom offline page is put into a nice safe cache. You can use the Cache API to do this. You get to create as many caches as you like, and you can call them whatever you want. Here, I’m going to call the cache Johnny just so I can refer to it as JohnnyCache in the code:
addEventListener('install', installEvent => {
installEvent.waitUntil(
caches.open('Johnny')
.then( JohnnyCache => {
JohnnyCache.addAll([
'/offline.html'
]); // end addAll
}) // end open.then
); // end waitUntil
}); // end addEventListener
I’m betting that your lovely offline page is linking to a CSS file, maybe an image or two, and perhaps some JavaScript. You can cache all of those at this point:
addEventListener('install', installEvent => {
installEvent.waitUntil(
caches.open('Johnny')
.then( JohnnyCache => {
JohnnyCache.addAll([
'/offline.html',
'/path/to/stylesheet.css',
'/path/to/javascript.js',
'/path/to/image.jpg'
]); // end addAll
}) // end open.then
); // end waitUntil
}); // end addEventListener
Make sure that the URLs are correct. If just one of the URLs in the list fails to resolve, none of the items in the list will be cached.
Intercept requests
The next event you want to listen for is the fetch event. This is probably the most powerful—and, let’s be honest, the creepiest—feature of a service worker. Once it has been installed, the service worker lurks on the user’s device, waiting for any requests made to your site. Every time the user requests a web page from your site, a fetch event will fire. Every time that page requests a style sheet or an image, a fetch event will fire. You can provide instructions for what should happen each time:
addEventListener('fetch', fetchEvent => {
// What happens next is up to you!
}); // end addEventListener
Let’s write a fairly conservative script with the following logic:
Whenever a file is requested,
First, try to fetch it from the network,
But if that doesn’t work, try to find it in the cache,
But if that doesn’t work, and it’s a request for a web page, show the custom offline page instead.
Here’s how that translates into JavaScript:
// Whenever a file is requested
addEventListener('fetch', fetchEvent => {
const request = fetchEvent.request;
fetchEvent.respondWith(
// First, try to fetch it from the network
fetch(request)
.then( responseFromFetch => {
return responseFromFetch;
}) // end fetch.then
// But if that doesn't work
.catch( fetchError => {
// try to find it in the cache
caches.match(request)
.then( responseFromCache => {
if (responseFromCache) {
return responseFromCache;
// But if that doesn't work
} else {
// and it's a request for a web page
if (request.headers.get('Accept').includes('text/html')) {
// show the custom offline page instead
return caches.match('/offline.html');
} // end if
} // end if/else
}) // end match.then
}) // end fetch.catch
); // end respondWith
}); // end addEventListener
I am fully aware that I may have done some owl-drawing there. If you need a more detailed breakdown of what’s happening at each point in the code, I’ve written a whole book for you. It’s the perfect present for Murphymas.
Hook up your service worker script
You can publish your service worker script at /serviceworker.js but you still need to tell the browser where to look for it. You can do that using JavaScript. Put this in an existing JavaScript file that you’re calling in to every page on your site, or add this in a script element at the end of every page’s HTML:
if (navigator.serviceWorker) {
navigator.serviceWorker.register('/serviceworker.js');
}
That tells the browser to start installing the service worker, but not without first checking that the browser understands what a service worker is. When it comes to JavaScript, feature detection is your friend.
You might already have some JavaScript files in a folder like /assets/js/ and you might be tempted to put your service worker script in there too. Don’t do that. If you do, the service worker will only be able to handle requests made to for files within /assets/js/. By putting the service worker script in the root directory, you’re making sure that every request can be intercepted.
Go further!
Nicely done! You’ve made sure that if—no, when—a visitor can’t reach your website, they’ll get your hand-tailored offline page. You have temporarily defeated the forces of chaos! You have briefly fought the tide of entropy! You have made a small but ultimately futile gesture against the inevitable heat-death of the universe!
This is just the beginning. You can do more with service workers.
What if, every time you fetched a page from the network, you stored a copy of that page in a cache? Then if that person tries to reach that page later, but they’re offline, you could show them the cached version.
Or, what if instead of reaching out the network first, you checked to see if a file is in the cache first? You could serve up that cached version—which would be blazingly fast—and still fetch a fresh version from the network in the background to pop in the cache for next time. That might be a good strategy for images.
So many options! The hard part isn’t writing the code, it’s figuring out the steps you want to take. Once you’ve got those steps written out, then it’s a matter of translating them into JavaScript.
Inevitably there will be some obstacles along the way—usually it’s a misplaced curly brace or a missing parenthesis. Don’t be too hard on yourself if your code doesn’t work at first. That’s just Murphy’s Law in action. |
2018 |
Jeremy Keith |
jeremykeith |
2018-12-04T00:00:00+00:00 |
https://24ways.org/2018/mistletoe-offline/ |
code |
| 100 |
Moo'y Christmas |
A note from the editors: Moo has changed their API since this article was written.
As the web matures, it is less and less just about the virtual world. It is becoming entangled with our world and it is harder to tell what is virtual and what is real. There are several companies who are blurring this line and make the virtual just an extension of the physical. Moo is one such company.
Moo offers simple print on demand services. You can print business cards, moo mini cards, stickers, postcards and more. They give you the ability to upload your images, customize them, then have them sent to your door. Many companies allow this sort of digital to physical interaction, but Moo has taken it one step further and has built an API.
Printable stocking stuffers
The Moo API consists of a simple XML file that is sent to their servers. It describes all the information needed to dynamically assemble and print your object. This is very helpful, not just for when you want to print your own stickers, but when you want to offer them to your customers, friends, organization or community with no hassle. Moo handles the check-out and shipping, all you need to do is what you do best, create!
Now using an API sounds complicated, but it is actually very easy. I am going to walk you through the options so you can easily be printing in no time.
Before you can begin sending data to the Moo API, you need to register and get an API key. This is important, because it allows Moo to track usage and to credit you. To register, visit http://www.moo.com/api/ and click “Request an API key”.
In the following examples, I will use {YOUR API KEY HERE} as a place holder, replace that with your API key and everything will work fine.
First thing you need to do is to create an XML file to describe the check-out basket. Open any text-editor and start with some XML basics. Don’t worry, this is pretty simple and Moo gives you a few tools to check your XML for errors before you order.
<?xml version="1.0" encoding="UTF-8"?>
<moo xsi:noNamespaceSchemaLocation="http://www.moo.com/xsd/api_0.7.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<request>
<version>0.7</version>
<api_key>{YOUR API KEY HERE}</api_key>
<call>build</call>
<return_to>http://www.example.com/return.html</return_to>
<fail_to>http://www.example.com/fail.html</fail_to>
</request>
<payload>
...
</payload>
</moo>
Much like HTML’s <head> and <body>, Moo has created <request> and <payload> elements all wrapped in a <moo> element.
The <request> element contains a few pieces of information that is the same across all the API calls. The <version> element describes which version of the API is being used. This is more important for Moo than for you, so just stick with “0.7” for now.
The <api_key> allows Moo to track sales, referrers and credit your account.
The <call> element can only take “build” so that is pretty straight forward. The <return_to> and <fail_to> elements are URLs. These are optional and are the URLs the customer is redirected to if there is an error, or when the check out process is complete. This allows for some basic branding and a custom “thank you” page which is under your control. That’s it for the <request> element, pretty easy so far!
Next up is the <payload> element. What goes inside here describes what is to be printed. There are two possible elements, we can put <chooser> or we can put <products> directly inside <payload>. They work in a similar ways, but they drop the customer into different parts of the Moo checkout process.
If you specify <products> then you send the customer straight to the Moo payment process. If you specify <chooser> then you send the customer one-step earlier where they are allowed to pick and choose some images, remove the ones they don’t like, adjust the crop, etc. The example here will use <chooser> but with a little bit of homework you can easily adjust to <products> if you desire.
...
<chooser>
<product_type>sticker</product_type>
<images>
<url>http://example.com/images/christmas1.jpg</url>
</images>
</chooser>
...
Inside the <chooser> element, we can see there are two basic piece of information. The type of product we want to print, and the images that are to be printed. The <product_type> element can take one of five options and is required! The possibilities are: minicard, notecard, sticker, postcard or greetingcard. We’ll now look at two of these more closely.
Moo Stickers
In the Moo sticker books you get 90 small squarish stickers in a small little booklet.
The simplest XML you could send would be something like the following payload:
...
<payload>
<chooser>
<product_type>sticker</product_type>
<images>
<url>http://example.com/image1.jpg</url>
</images>
<images>
<url>http://example.com/image2.jpg</url>
</images>
<images>
<url>http://example.com/image3.jpg</url>
</images>
</chooser>
</payload>
...
This creates a sticker book with only 3 unique images, but 30 copies of each image. The Sticker books always print 90 stickers in multiples of the images you uploaded. That example only has 3 <images> elements, but you can easily duplicate the XML and send up to 90. The <url> should be the full path to your image and the image needs to be a minimum of 300 pixels by 300 pixels.
You can add more XML to describe cropping, but the simplest option is to either, let your customers choose or to pre-crop all your images square so there are no issues.
The full XML you would post to the Moo API to print sticker books would look like this:
<?xml version="1.0" encoding="UTF-8"?>
<moo xsi:noNamespaceSchemaLocation="http://www.moo.com/xsd/api_0.7.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<request>
<version>0.7</version>
<api_key>{YOUR API KEY HERE}</api_key>
<call>build</call>
<return_to>http://www.example.com/return.html</return_to>
<fail_to>http://www.example.com/fail.html</fail_to>
</request>
<payload>
<chooser>
<product_type>sticker</product_type>
<images>
<url>http://example.com/image1.jpg</url>
</images>
<images>
<url>http://example.com/image2.jpg</url>
</images>
<images>
<url>http://example.com/image3.jpg</url>
</images>
</chooser>
</payload>
</moo>
Mini-cards
The mini-cards are the small cute business cards in 14×35 dimensions and come in packs of 100.
Since the mini-cards are print on demand, this allows you to have 100 unique images on the back of the cards.
Just like the stickers example, we need the same XML setup. The <moo> element and <request> elements will be the same as before. The part you will focus on is the <payload> section.
Since you are sending along specific information, we can’t use the <chooser> option any more. Switch this to <products> which has a child of <product>, which in turn has a <product_type> and <designs>. This might seem like a lot of work, but once you have it set up you won’t need to change it.
...
<payload>
<products>
<product>
<product_type>minicard</product_type>
<designs>
...
</designs>
</product>
</products>
</payload>
...
So now that we have the basic framework, we can talk about the information specific to minicards. Inside the <designs> element, you will have one <design> for each card. Much like before, this contains a way to describe the image. Note that this time the element is called <image>, not images plural.
Inside the <image> element you have a <url> which points to where the image lives and a <type>. The <type> should just be set to ‘variable’. You can pass crop information here instead, but we’re going to keep it simple for this tutorial. If you are interested in how that works, you should refer to the official API documentation.
...
<design>
<image>
<url>http://example.com/image1.jpg</url>
<type>variable</type>
</image>
</design>
...
So far, we have managed to build a pack of 100 Moo mini-cards with the same image on the front. If you wanted 100 different images, you just need to replicate this snippit, 99 more times.
That describes the front design, but the flip-side of your mini-cards can contain 6 lines of text, which is customizable in a variety of colors, fonts and styles.
The API allows you to create different text on the back of each mini-card, something the web interface doesn’t implement. To describe the text on the mini-card we need to add a <text_collection> element inside the <design> element. If you skip this element, the back of your mini-card will just be blank, but that’s not very festive!
Inside the <text_collection> element, we need to describe the type of text we want to format, so we add a <minicard> element, which in turn contains all the lines of text. Each of Moo’s printed products take different numbers of lines of text, so if you are not planning on making mini-cards, be sure to consult the documentation.
For mini-cards, we can have 6 distinct lines, each with their own style and layout. Each line is represented by an element <text_line> which has several optional children. The <id> tells which line of the 6 to print the text one. The <string> is the text you want to print and it must be shorter than 38 characters. The <bold> element is false by default, but if you want your text bolded, then add this and set it to true.
The <align> element is also optional. By default it is set to align left. You can also set this to right or center if you desirer. The <font> element takes one of 3 types, modern, traditional or typewriter. The default is modern. Finally, you can set the <colour>, yes that’s color with a ‘u’, Moo is a British company, so they get to make the rules. When you start a print on demand company, you can spell it however you want. The <colour> element takes a 6 character hex value with a leading #.
<design>
...
<text_collection>
<minicard>
<text_line>
<id>(1-6)</id>
<string>String, I must be less than 38 chars!</string>
<bold>true</bold>
<align>left</align>
<font>modern</font>
<colour>#ff0000</colour>
</text_line>
</minicard>
</text_collection>
</design>
If you combine all of this into a mini-card request you’d get this example:
<?xml version="1.0" encoding="UTF-8"?>
<moo xsi:noNamespaceSchemaLocation="http://www.moo.com/xsd/api_0.7.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<request>
<version>0.7</version>
<api_key>{YOUR API KEY HERE}</api_key>
<call>build</call>
<return_to>http://www.example.com/return.html</return_to>
<fail_to>http://www.example.com/fail.html</fail_to>
</request>
<payload>
<products>
<product>
<product_type>minicard</product_type>
<designs>
<design>
<image>
<url>http://example.com/image1.jpg</url>
<type>variable</type>
</image>
<text_collection>
<minicard>
<text_line>
<id>1</id>
<string>String, I must be less than 38 chars!</string>
<bold>true</bold>
<align>left</align>
<font>modern</font>
<colour>#ff0000</colour>
</text_line>
</minicard>
</text_collection>
</design>
</designs>
</product>
</products>
</payload>
</moo>
Now you know how to construct the XML that describes what to print. Next, you need to know how to send it to Moo to make it happen!
Posting to the API
So your XML is file ready to go. First thing we need to do is check it to make sure it’s valid. Moo has created a simple validator where you paste in your XML, and it alerts you to problems.
When you have a fully valid XML file, you’ll want to send that to the Moo API. There are a few ways to do this, but the simplest is with an HTML form.
This is the sample code for an HTML form with a big “Buy My Stickers” button. Once you know that it is working, you can use all your existing HTML knowledge to style it up any way you like.
<form method="POST" action="http://www.moo.com/api/api.php">
<input type="hidden" name="xml" value="<?xml version="1.0" encoding="UTF-8"?> <moo xsi:noNamespaceSchemaLocation="http://www.moo.com/xsd/api_0.7.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <request>....</request> <payload>...</payload> </moo> ">
<input type="submit" name="submit" value="Buy My Stickers"/>
</form>
This is just a basic <form> element that submits to the Moo API, http://www.moo.com/api/api.php, when someone clicks the button. There is a hidden input called “xml” which contains the value the XML file we created previously.
For those of you who need to “view source” to fully understand what’s happening can see a working version and peek under the hood.
Using the API has advantages over uploading the images directly yourself. The images and text that you send via the API can be dynamic. Some companies, like Dopplr, have taken user profiles and dynamic data that changes every minute to generate customer stickers of places that you’ve travelled to or mini-cards with a world map of all the cities you have visited. Every single customer has different travel plans and therefore different sets of stickers and mini-card maps. The API allows for the utmost current information to be printed, on demand, in real-time.
Go forth and Moo’ltiply
See, making an API call wasn’t that hard was it? You are now 90% of the way to creating anything with the Moo API. With a bit of reading, you can learn that extra 10% and print any Moo product. Be on the lookout in 2009 for the official release of the 1.0 API with improvements and some extras that were not available when this article was written.
This article is released under the creative-commons attribution share-a-like license. That means you are free to re-distribute it, mash it up, translate it and otherwise re-using it ways the author never considered, in return he only asks you mention his name.
This work by Brian Suda is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License. |
2008 |
Brian Suda |
briansuda |
2008-12-19T00:00:00+00:00 |
https://24ways.org/2008/mooy-christmas/ |
code |