rowid,title,contents,year,author,author_slug,published,url,topic 124,Writing Responsible JavaScript,"Without a doubt, JavaScript has been making something of a comeback in the last year. If you’re involved in client-side development in any way at all, chances are that you’re finding yourself writing more JavaScript now than you have in a long time. If you learned most of your JavaScript back when DHTML was all the rage and before DOM Scripting was in vogue, there have been some big shifts in the way scripts are written. Most of these are in the way event handlers are assigned and functions declared. Both of these changes are driven by the desire to write scripts that are responsible page citizens, both in not tying behaviour to content and in taking care not to conflict with other scripts. I thought it may be useful to look at some of these more responsible approaches to learn how to best write scripts that are independent of the page content and are safely portable between different applications. Event Handling Back in the heady days of Web 1.0, if you wanted to have an object on the page react to something like a click, you would simply go ahead and attach an onclick attribute. This was easy and understandable, but much like the font tag or the style attribute, it has the downside of mixing behaviour or presentation in with our content. As we’re learned with CSS, there are big benefits in keeping those layers separate. Hey, if it works for CSS, it should work for JavaScript too. Just like with CSS, instead of adding an attribute to our element within the document, the more responsible way to do that is to look for the item from your script (like CSS does with a selector) and then assign the behaviour to it. To give an example, take this oldskool onclick use case: Play the animation This could be rewritten by removing the onclick attribute, and instead doing the following from within your JavaScript. document.getElementById('anim-link').onclick = playAnimation; It’s all in the timing Of course, it’s never quite that easy. To be able to attach that onclick, the element you’re targeting has to exist in the page, and the page has to have finished loading for the DOM to be available. This is where the onload event is handy, as it fires once everything has finished loading. Common practise is to have a function called something like init() (short for initialise) that sets up all these event handlers as soon as the page is ready. Back in the day we would have used the onload attibute on the
element to do this, but of course what we really want is: window.onload = init; As an interesting side note, we’re using init here rather than init() so that the function is assigned to the event. If we used the parentheses, the init function would have been run at that moment, and the result of running the function (rather than the function itself) would be assigned to the event. Subtle, but important. As is becoming apparent, nothing is ever simple, and we can’t just go around assigning our initialisation function to window.onload. What if we’re using other scripts in the page that might also want to listen out for that event? Whichever script got there last would overwrite everything that came before it. To manage this, we need a script that checks for any existing event handlers, and adds the new handler to it. Most of the JavaScript libraries have their own systems for doing this. If you’re not using a library, Simon Willison has a good stand-alone example function addLoadEvent(func) { var oldonload = window.onload; if (typeof window.onload != 'function') { window.onload = func; } else { window.onload = function() { if (oldonload) { oldonload(); } func(); } } } Obviously this is just a toe in the events model’s complex waters. Some good further reading is PPK’s Introduction to Events. Carving out your own space Another problem that rears its ugly head when combining multiple scripts on a single page is that of making sure that the scripts don’t conflict. One big part of that is ensuring that no two scripts are trying to create functions or variables with the same names. Reusing a name in JavaScript just over-writes whatever was there before it. When you create a function in JavaScript, you’ll be familiar with doing something like this. function foo() { ... goodness ... } This is actually just creating a variable called foo and assigning a function to it. It’s essentially the same as the following. var foo = function() { ... goodness ... } This name foo is by default created in what’s known as the ‘global namespace’ – the general pool of variables within the page. You can quickly see that if two scripts use foo as a name, they will conflict because they’re both creating those variables in the global namespace. A good solution to this problem is to add just one name into the global namespace, make that one item either a function or an object, and then add everything else you need inside that. This takes advantage of JavaScript’s variable scoping to contain you mess and stop it interfering with anyone else. Creating An Object Say I was wanting to write a bunch of functions specifically for using on a site called ‘Foo Online’. I’d want to create my own object with a name I think is likely to be unique to me. var FOOONLINE = {}; We can then start assigning functions are variables to it like so: FOOONLINE.message = 'Merry Christmas!'; FOOONLINE.showMessage = function() { alert(this.message); }; Calling FOOONLINE.showMessage() in this example would alert out our seasonal greeting. The exact same thing could also be expressed in the following way, using the object literal syntax. var FOOONLINE = { message: 'Merry Christmas!', showMessage: function() { alert(this.message); } }; Creating A Function to Create An Object We can extend this idea bit further by using a function that we run in place to return an object. The end result is the same, but this time we can use closures to give us something like private methods and properties of our object. var FOOONLINE = function(){ var message = 'Merry Christmas!'; return { showMessage: function(){ alert(message); } } }(); There are two important things to note here. The first is the parentheses at the end of line 10. Just as we saw earlier, this runs the function in place and causes its result to be assigned. In this case the result of our function is the object that is returned at line 4. The second important thing to note is the use of the var keyword on line 2. This ensures that the message variable is created inside the scope of the function and not in the global namespace. Because of the way closure works (which if you’re not familiar with, just suspend your disbelief for a moment) that message variable is visible to everything inside the function but not outside. Trying to read FOOONLINE.message from the page would return undefined. This is useful for simulating the concept of private class methods and properties that exist in other programming languages. I like to take the approach of making everything private unless I know it’s going to be needed from outside, as it makes the interface into your code a lot clearer for someone else to read. All Change, Please So that was just a whistle-stop tour of a couple of the bigger changes that can help to make your scripts better page citizens. I hope it makes useful Sunday reading, but obviously this is only the tip of the iceberg when it comes to designing modular, reusable code. For some, this is all familiar ground already. If that’s the case, I encourage you to perhaps submit a comment with any useful resources you’ve found that might help others get up to speed. Ultimately it’s in all of our interests to make sure that all our JavaScript interoperates well – share your tips.",2006,Drew McLellan,drewmclellan,2006-12-10T00:00:00+00:00,https://24ways.org/2006/writing-responsible-javascript/,code 144,"The Mobile Web, Simplified","A note from the editors: although eye-opening in 2006, this article is no longer relevant to today’s mobile web. Considering a foray into mobile web development? Following are four things you need to know before making the leap. 1. 4 billion mobile subscribers expected by 2010 Fancy that. Coupled with the UN prediction of 6.8 billion humans by 2010, 4 billion mobile subscribers (source) is an astounding 59% of the planet. Just how many of those subscribers will have data plans and web-enabled phones is still in question, but inevitably this all means one thing for you and me: A ton of potential eyes to view our web content on a mobile device. 2. Context is king Your content is of little value to users if it ignores the context in which it is viewed. Consider how you access data on your mobile device. You might be holding a bottle of water or gripping a handle on the subway/tube. You’re probably seeking specific data such as directions or show times, rather than the plethora of data at your disposal via a desktop PC. The mobile web, a phrase often used to indicate “accessing the web on a mobile device”, is very much a context-, content-, and component-specific environment. Expressed in terms of your potential target audience, access to web content on a mobile device is largely influenced by surrounding circumstances and conditions, information relevant to being mobile, and the feature set of the device being used. Ask yourself, What is relevant to my users and the tasks, problems, and needs they may encounter while being mobile? Answer that question and you’ll be off to a great start. 3. WAP 2.0 is an XHTML environment In a nutshell, here are a few fundamental tenets of mobile internet technology: Wireless Application Protocol (WAP) is the protocol for enabling mobile access to internet content. Wireless Markup Language (WML) was the language of choice for WAP 1.0. Nearly all devices sold today are WAP 2.0 devices. With the introduction of WAP 2.0, XHTML Mobile Profile (XHTML-MP) became the preferred markup language. XHTML-MP will be familiar to anyone experienced with XHTML Transitional or Strict. Summary? 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. With WML on the decline, the learning curve is much smaller today than it was several years ago. I’m generalizing things gratuitously, but the point remains: Get off yo’ lazy butt and begin to take mobile seriously. I’ll even pass you a few tips for getting started. First, the DOCTYPE for XHTML-MP is as follows: As for MIME type, Open Mobile Alliance (OMA) specifies using the MIME type application/vnd.wap.xhtml+xml, but ultimately you need to ensure the server delivering your mobile content is configured properly for the MIME type you choose to use, as there are other options (see Setting up WAP Servers). Once you’ve made it to the body, the XHTML-MP markup is not unlike what you’re already used to. A few resources worth skimming: Developers Home XHTML-MP Tutorial – An impressively replete resource for all things XHTML-MP XHTML-MP Tags List – A complete list of XHTML-MP elements and accompanying attributes And last but certainly not least, CSS. There exists WAP CSS, which is essentially a subset of CSS2 with WAP-specific extensions. For all intents and purposes, much of the CSS you’re already comfortable using will be transferrable to mobile. As for including CSS in your pages, your options are the same as for desktop sites: external, embedded, and inline. Some experts will argue embedded or inline over external in favor of reducing the number of HTTP connections per page request, yet many popular mobilized sites and apps employ external linking without issue. Stocking stuffers: Flickr Mobile, Fandango Mobile, and Popurls Mobile. A few sites with whom you can do the View Source song and dance for further study. 4. “Cell phone” is so DynaTAC If you’re a U.S. resident, listen up: You must rid your vocabulary of the term “cell phone”. We’re one of the few economies on the planet to refer to a mobile phone accordingly. If you care to find yourself in any of the worthwhile mobile development circles, begin using terms more widely accepted: “mobile” or “mobile phone” or “handset” or “handy”. If you’re not sure which, go for “mobile”. Such as, “Yo dog, check out my new mobile.” More importantly, however, is overcoming the mentality that access to the mobile web can be done only with a phone. Instead, “device” encourages us to think phone, handheld computer, watch, Nintendo DS, car, you name it. Simple enough?",2006,Cameron Moll,cameronmoll,2006-12-19T00:00:00+00:00,https://24ways.org/2006/the-mobile-web-simplified/,ux 132,Tasty Text Trimmer,"In most cases, when designing a user interface it’s best to make a decision about how data is best displayed and stick with it. Failing to make a decision ultimately leads to too many user options, which in turn can be taxing on the poor old user. Under some circumstances, however, it’s good to give the user freedom in customising their workspace. One good example of this is the ‘Article Length’ tool in Apple’s Safari RSS reader. Sliding a slider left of right dynamically changes the length of each article shown. It’s that kind of awesomey magic stuff that’s enough to keep you from sleeping. Let’s build one. The Setup Let’s take a page that has lots of long text items, a bit like a news page or like Safari’s RSS items view. If we were to attach a class name to each element we wanted to resize, that would give us something to hook onto from the JavaScript. Example 1: The basic page. As you can see, I’ve wrapped my items in a DIV and added a class name of chunk to them. It’s these chunks that we’ll be finding with the JavaScript. Speaking of which … Our Core Functions There are two main tasks that need performing in our script. The first is to find the chunks we’re going to be resizing and store their original contents away somewhere safe. We’ll need this so that if we trim the text down we’ll know what it was if the user decides they want it back again. We’ll call this loadChunks. var loadChunks = function(){ var everything = document.getElementsByTagName('*'); var i, l; chunks = []; for (i=0, l=everything.length; iWeb Directions Conference Pty Ltd
Here’s our CSS for this element .fn { background-image: url(images/topright.png); background-repeat: no-repeat; background-position: top right; padding-top: 2em; font-weight: bold; font-size: 1.1em; } Again, we don’t want it to repeat, but this time, we’ve specified a background position for the image. This will make the background image start from the top, but its right edge will be located at the right edge of the element. I also made the font size a little bigger, and the weight bold, to differentiate it from the rest of the text in the hCard. Here’s the image we are adding as the background to this element. So, putting these two CSS statements together we get We specified a padding-top of 2em to give some space between the content of the fn element and the edge of the fn element. Otherwise the top of the hCard image would be hard against the border. To see this in action, just remove the padding-top: 2em; declaration and preview in a browser. So, with just two statements, we are well under way. We’ve not even had to add any HTML so far. Let’s turn to the bottom of the element, and add the bottom border (well, the background image which will serve as that border). Now, which element are we going to use to add this background image to? OK, here I have to admit to a little, teensie bit of cheating. If you look at the HTML of the hCard, I’ve grouped the email and telephone properties into a div, with a class of telecommunications. This grouping is not strictly requred for our hCard.Phone/Fax: Work: 61 2 9365 5007
Email: info@webdirections.org
Email: info@webdirections.org
Typically, in hCard, the value part of this property isn’t required, and we could get away with info@webdirections.org The form I’ve used, with the span of class value is however, perfectly valid hCard markup (hard allows for multiple email addresses of different types, which is where this typically comes in handy). Why have I gone to all this trouble? Well, when it came to styling the hCard, I realized I needed a block element to attach the background image for the bottom right hand corner to. Typically the last block element in the containing element is the ideal choice (and sometimes it’s possible to take an inline element, for example the link here, and use CSS to make it a block element, and attach it to that, but that really doesn’t work with this design). So, if we are going to use the paragraph which contains the email link, we need a way to select it exclusively, which means that with CSS2 at least, we need a class or id as a hook for our CSS selector (in CSS3 we could use the last-child selector, which selects the last child element of a specified element, but again, as last child is not widely supported, we won’t rely on it here.) So, the least worst thing we could do is take an existing element, and add some reasonably meaningful markup to it. That’s why we gave the paragraph a class of email, and the email address a class of value. Which reminds me a little of a moment in Hamlet The lady doth protest too much, methinks OK, let’s get back to the CSS. We add the bottom right corner image, positioning it in the bottom right of the element, and making sure it doesn’t repeat. We also add some padding to the bottom, to balance out the padding we added to the top of the hCard. p.email { background-image: url(images/bottom-right.png); background-position: right bottom; background-repeat: no-repeat; padding-bottom: 2em; } Which all goes to make our hCard look like this It just remains for us to clean up a little. Let’s start from the top. We’ll float the download image to the right like this .vcard img { float: right; padding-right: 1em; margin-top: -1em } See how we didn’t have to add a class to style the image, we used the fact that the image is a descendent of the vcard element, and a descendent selector. In my experience, the very widely supported, powerful descendent selector is one of the most underused aspects of CSS. So if you don’t use it frequently, look into it in more detail. We added some space to the right of the image, and pulled it up a bit closer to the top of the hCard, like this We also want to add some whitespace between the edge of the hCard and the text. We would typically add padding to the left of the containing element, (in this case the vcard element) but this would break our bottom left hand corner, like this That’s because the div element we added this bottom left background image to would be moved in by the padding on its containing element. So instead, we add left margin to all the paragraphs in the hCard .vcard p { margin-left: 1em; } (there is the descendent selector again – it is the swiss army knife of CSS) Now, we’ve not yet made the width of the hCard a function of the size of the text inside it (or “em driven” as we described it earlier). We do this by giving the hCard a width that is specified in em units. Here we’ll set a width of say 28em, which makes the hCard always roughly as wide as 28 characters (strictly speaking 28 times the width of the letter capital M). So the statement for our containing vcard element becomes .vcard { background-image: url(images/vcardfill.png); background-repeat: no-repeat; color: #666; font-family: ""Lucida Grande"", Verdana, Helvetica, Arial, sans-serif; width: 28em; } and now our element will look like this We’ve used almost entirely the existing HTML from our original hCard (adding just a little, and trying as much as possible to keep that additional markup meaningful), and just 6 CSS statements. Holiday Bonus – a downloadable vCard Did you notice this part of the HTML What’s with the odd looking url The span inside each legend is because legend elements are highly resistant to styling! Indeed they’re one of the most stubborn elements in the browsers’ vocabulary. Oh man … how I wrestled with the buggers … until this obvious alternative occurred to me! So the legend element itself is just a container, while all the styling is on the inner span. Oh yeah, there was some CSS too I’m not gonna dwell too much on the CSS it took to make this work – this is a short article, and it’s all there in the demo [demo page, style sheet] But I do want to touch on the most interesting bit – where we get from a layout with headers on every row, to one where only the top row has headers – or at least, so it appears to graphical browsers. For screen readers, as we noted, we need those headers on every row, so we should employ some cunning CSS to partly negate their visual presence, without removing them from the output. The core styling for each label span is like this: label span { display:block; padding:5px; line-height:1em; background:#423221; color:#fff; font-weight:bold; } But in the rows below the header they have these additional rules: fieldset.body label span { padding:0 5px; line-height:0; position:relative; top:-10000em; } The rendered width of the element is preserved, ensuring that the surrounding label is still the same width as the one in the header row above, and hence a unified column width is preserved all the way down. But the element effectively has no height, and so it’s effectively invisible. The styling is done this way, rather than just setting the height to zero and using overflow:hidden, because to do that would expose an unrelated quirk with another popular screen reader! (It would hide the output from Window Eyes, as shown in this test example at access matters.) The finished widget It’s an intricate beast allright! But after all that we do indeed get the widget we want: Demo page Style sheet It’s not perfect, most notably because the legends have to have a fixed width; this can be in em to allow for text scaling, but it still doesn’t allow the content to break into multiple lines. It also doesn’t look quite right in Safari; and some CSS hacking was needed to make it look right in IE6 and IE7. Still it worked well enough for the purpose, and satisfied the client completely. And most of all it re-assured me in my faith – that there’s never any need to abuse tables for layout. (Unless of course you think this content is a table anyway, but that’s another story!)",2006,James Edwards,jamesedwards,2006-12-11T00:00:00+00:00,https://24ways.org/2006/showing-good-form/,ux 138,Rounded Corner Boxes the CSS3 Way,"If you’ve been doing CSS for a while you’ll know that there are approximately 3,762 ways to create a rounded corner box. The simplest techniques rely on the addition of extra mark-up directly to your page, while the more complicated ones add the mark-up though DOM manipulation. While these techniques are all very interesting, they do seem somewhat of a kludge. The goal of CSS is to separate structure from presentation, yet here we are adding superfluous mark-up to our code in order to create a visual effect. The reason we are doing this is simple. CSS2.1 only allows a single background image per element. Thankfully this looks set to change with the addition of multiple background images into the CSS3 specification. With CSS3 you’ll be able to add not one, not four, but eight background images to a single element. This means you’ll be able to create all kinds of interesting effects without the need of those additional elements. While the CSS working group still seem to be arguing over the exact syntax, Dave Hyatt went ahead and implemented the currently suggested mechanism into Safari. The technique is fiendishly simple, and I think we’ll all be a lot better off once the W3C stop arguing over the details and allow browser vendors to get on and provide the tools we need to build better websites. To create a CSS3 rounded corner box, simply start with your box element and apply your 4 corner images, separated by commas. .box { background-image: url(top-left.gif), url(top-right.gif), url(bottom-left.gif), url(bottom-right.gif); } We don’t want these background images to repeat, which is the normal behaviour, so lets set all their background-repeat properties to no-repeat. .box { background-image: url(top-left.gif), url(top-right.gif), url(bottom-left.gif), url(bottom-right.gif); background-repeat: no-repeat, no-repeat, no-repeat, no-repeat; } Lastly, we need to define the positioning of each corner image. .box { background-image: url(top-left.gif), url(top-right.gif), url(bottom-left.gif), url(bottom-right.gif); background-repeat: no-repeat, no-repeat, no-repeat, no-repeat; background-position: top left, top right, bottom left, bottom right; } And there we have it, a simple rounded corner box with no additional mark-up. As well as using multiple background images, CSS3 also has the ability to create rounded corners without the need of any images at all. You can do this by setting the border-radius property to your desired value as seen in the next example. .box { border-radius: 1.6em; } This technique currently works in Firefox/Camino and creates a nice, if somewhat jagged rounded corner. If you want to create a box that works in both Mozilla and WebKit based browsers, why not combine both techniques and see what happens.",2006,Andy Budd,andybudd,2006-12-04T00:00:00+00:00,https://24ways.org/2006/rounded-corner-boxes-the-css3-way/,code 142,Revealing Relationships Can Be Good Form,"A few days ago, a colleague of mine – someone I have known for several years, who has been doing web design for several years and harks back from the early days of ZDNet – was running through a prototype I had put together for some user testing. As with a lot of prototypes, there was an element of ‘smoke and mirrors’ to make things look like they were working. One part of the form included a yes/no radio button, and selecting the Yes option would, in the real and final version of the form, reveal some extra content. Rather than put too much JavaScript in the prototype, I took a preverbial shortcut and created a link which I wrapped around the text next to the radio button – clicking on that link would cause the form to mimic a change event on the radio button. But it wasn’t working for him. Why was that? Because whereas I created the form using a