, 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.\n\nYou should also check the user\u2019s credentials to make sure they have permission to edit whatever it is they\u2019re editing. Basically the same rules apply as with any script in your application.\n\nLimitations\n\nThere are a few bits and bobs that in an ideal world I would tidy up. The first is the error handling, as I\u2019ve already mentioned. The second is that from an idealistic standpoint, I\u2019d rather not be using innerHTML. However, the reality is that it\u2019s presently the most efficient way of making large changes to the document. If you\u2019re serving as XML, remember that you\u2019ll need to replace these with proper DOM nodes.\n\nIt\u2019s also important to note that it\u2019s 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\u2019t cope well. The benefit of this technique, though, is that if JavaScript is unavailable none of the functionality gets implemented at all \u2013 it fails silently. It is for this reason that this shouldn\u2019t be used as a complete replacement for a traditional, universally accessible edit form. It\u2019s a great time-saver for those with the ability to use it, but it\u2019s no replacement.\n\nSee it in action\n\nI\u2019ve put together an example page using the inert PHP script above. That is to say, your edits aren\u2019t committed to a database, so the example is reset when the page is reloaded.", "year": "2005", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2005-12-23T00:00:00+00:00", "url": "https://24ways.org/2005/edit-in-place-with-ajax/", "topic": "code"} {"rowid": 132, "title": "Tasty Text Trimmer", "contents": "In most cases, when designing a user interface it\u2019s 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. \n\nUnder some circumstances, however, it\u2019s good to give the user freedom in customising their workspace. One good example of this is the \u2018Article Length\u2019 tool in Apple\u2019s Safari RSS reader. Sliding a slider left of right dynamically changes the length of each article shown. It\u2019s that kind of awesomey magic stuff that\u2019s enough to keep you from sleeping. Let\u2019s build one.\n\nThe Setup\n\nLet\u2019s take a page that has lots of long text items, a bit like a news page or like Safari\u2019s 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. \n\nExample 1: The basic page.\n\nAs you can see, I\u2019ve wrapped my items in a DIV and added a class name of chunk to them. It\u2019s these chunks that we\u2019ll be finding with the JavaScript. Speaking of which \u2026\n\nOur Core Functions\n\nThere are two main tasks that need performing in our script. The first is to find the chunks we\u2019re going to be resizing and store their original contents away somewhere safe. We\u2019ll need this so that if we trim the text down we\u2019ll know what it was if the user decides they want it back again. We\u2019ll call this loadChunks. \n\nvar loadChunks = function(){\n\tvar everything = document.getElementsByTagName('*');\n\tvar i, l;\n\tchunks\t= [];\n\tfor (i=0, l=everything.length; i -1){\n\t\t\tchunks.push({\n\t\t\t\tref: everything[i],\n\t\t\t\toriginal: everything[i].innerHTML\n\t\t\t});\n\t\t}\n\t}\n};\n\nThe variable chunks is stored outside of this function so that we can access it from our next core function, which is doTrim.\n\nvar doTrim = function(interval) {\n\tif (!chunks) loadChunks();\n\tvar i, l;\n\tfor (i=0, l=chunks.length; iPlay the animation\n\nThis could be rewritten by removing the onclick attribute, and instead doing the following from within your JavaScript.\n\ndocument.getElementById('anim-link').onclick = playAnimation;\n\nIt\u2019s all in the timing\n\nOf course, it\u2019s never quite that easy. To be able to attach that onclick, the element you\u2019re 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.\n\nBack in the day we would have used the onload attibute on the element to do this, but of course what we really want is:\n\nwindow.onload = init;\n\nAs an interesting side note, we\u2019re 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.\n\nAs is becoming apparent, nothing is ever simple, and we can\u2019t just go around assigning our initialisation function to window.onload. What if we\u2019re 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\u2019re not using a library, Simon Willison has a good stand-alone example\n\nfunction addLoadEvent(func) {\n\tvar oldonload = window.onload;\n\tif (typeof window.onload != 'function') {\n\t\twindow.onload = func;\n\t} else {\n\t\twindow.onload = function() {\n\t\t\tif (oldonload) {\n\t\t\t\toldonload();\n\t\t\t}\n\t\t\tfunc();\n\t\t}\n\t}\n}\n\nObviously this is just a toe in the events model\u2019s complex waters. Some good further reading is PPK\u2019s Introduction to Events.\n\nCarving out your own space\n\nAnother problem that rears its ugly head when combining multiple scripts on a single page is that of making sure that the scripts don\u2019t 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.\n\nWhen you create a function in JavaScript, you\u2019ll be familiar with doing something like this.\n\nfunction foo() {\n\t... goodness ...\n}\n\nThis is actually just creating a variable called foo and assigning a function to it. It\u2019s essentially the same as the following.\n\nvar foo = function() {\n\t... goodness ...\n}\n\nThis name foo is by default created in what\u2019s known as the \u2018global namespace\u2019 \u2013 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\u2019re both creating those variables in the global namespace.\n\nA 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\u2019s variable scoping to contain you mess and stop it interfering with anyone else.\n\nCreating An Object\n\nSay I was wanting to write a bunch of functions specifically for using on a site called \u2018Foo Online\u2019. I\u2019d want to create my own object with a name I think is likely to be unique to me.\n\nvar FOOONLINE = {};\n\nWe can then start assigning functions are variables to it like so:\n\nFOOONLINE.message = 'Merry Christmas!';\nFOOONLINE.showMessage = function() {\n\talert(this.message);\n};\n\nCalling 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.\n\nvar FOOONLINE = {\n\tmessage: 'Merry Christmas!',\n\tshowMessage: function() {\n\t\talert(this.message);\n\t}\n};\n\nCreating A Function to Create An Object\n\nWe 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.\n\nvar FOOONLINE = function(){\n\tvar message = 'Merry Christmas!';\n\treturn {\n\t\tshowMessage: function(){\n\t\t\talert(message);\n\t\t}\n\t}\n}();\n\nThere 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.\n\nThe 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\u2019re 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.\n\nThis 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\u2019s going to be needed from outside, as it makes the interface into your code a lot clearer for someone else to read. \n\nAll Change, Please\n\nSo 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.\n\nFor some, this is all familiar ground already. If that\u2019s the case, I encourage you to perhaps submit a comment with any useful resources you\u2019ve found that might help others get up to speed. Ultimately it\u2019s in all of our interests to make sure that all our JavaScript interoperates well \u2013 share your tips.", "year": "2006", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2006-12-10T00:00:00+00:00", "url": "https://24ways.org/2006/writing-responsible-javascript/", "topic": "code"} {"rowid": 165, "title": "Transparent PNGs in Internet Explorer 6", "contents": "Newer breeds of browser such as Firefox and Safari have offered support for PNG images with full alpha channel transparency for a few years. With the use of hacks, support has been available in Internet Explorer 5.5 and 6, but the hacks are non-ideal and have been tricky to use. With IE7 winning masses of users from earlier versions over the last year, full PNG alpha-channel transparency is becoming more of a reality for day-to-day use.\n\nHowever, there are still numbers of IE6 users out there who we can\u2019t leave out in the cold this Christmas, so in this article I\u2019m going to look what we can do to support IE6 users whilst taking full advantage of transparency for the majority of a site\u2019s visitors.\n\nSo what\u2019s alpha channel transparency?\n\nCast your minds back to the Ghost of Christmas Past, the humble GIF. Images in GIF format offer transparency, but that transparency is either on or off for any given pixel. Each pixel\u2019s either fully transparent, or a solid colour. In GIF, transparency is effectively just a special colour you can chose for a pixel.\n\nThe PNG format tackles the problem rather differently. As well as having any colour you chose, each pixel also carries a separate channel of information detailing how transparent it is. This alpha channel enables a pixel to be fully transparent, fully opaque, or critically, any step in between.\n\nThis enables designers to produce images that can have, for example, soft edges without any of the \u2018halo effect\u2019 traditionally associated with GIF transparency. If you\u2019ve ever worked on a site that has different colour schemes and therefore requires multiple versions of each graphic against a different colour, you\u2019ll immediately see the benefit. \n\nWhat\u2019s perhaps more interesting than that, however, is the extra creative freedom this gives designers in creating beautiful sites that can remain web-like in their ability to adjust, scale and reflow.\n\nThe Internet Explorer problem\n\nUp until IE7, there has been no fully native support for PNG alpha channel transparency in Internet Explorer. However, since IE5.5 there has been some support in the form of proprietary filter called the AlphaImageLoader. Internet Explorer filters can be applied directly in your CSS (for both inline and background images), or by setting the same CSS property with JavaScript. \n\nCSS:\n\nimg {\n\tfilter: progid:DXImageTransform.Microsoft.AlphaImageLoader(...);\n}\n\nJavaScript:\n\nimg.style.filter = \"progid:DXImageTransform.Microsoft.AlphaImageLoader(...)\";\n\nThat may sound like a problem solved, but all is not as it may appear. Firstly, as you may realise, there\u2019s no CSS property called filter in the W3C CSS spec. It\u2019s a proprietary extension added by Microsoft that could potentially cause other browsers to reject your entire CSS rule. \n\nSecondly, AlphaImageLoader does not magically add full PNG transparency support so that a PNG in the page will just start working. Instead, when applied to an element in the page, it draws a new rendering surface in the same space that element occupies and loads a PNG into it. If that sounds weird, it\u2019s because that\u2019s precisely what it is. However, by and large the result is that PNGs with an alpha channel can be accommodated.\n\nThe pitfalls\n\nSo, whilst support for PNG transparency in IE5.5 and 6 is possible, it\u2019s not without its problems.\n\nBackground images cannot be positioned or repeated\n\nThe AlphaImageLoader does work for background images, but only for the simplest of cases. If your design requires the image to be tiled (background-repeat) or positioned (background-position) you\u2019re out of luck. The AlphaImageLoader allows you to set a sizingMethod to either crop the image (if necessary) or to scale it to fit. Not massively useful, but something at least.\n\nDelayed loading and resource use\n\nThe AlphaImageLoader can be quite slow to load, and appears to consume more resources than a standard image when applied. Typically, you\u2019d need to add thousands of GIFs or JPEGs to a page before you saw any noticeable impact on the browser, but with the AlphaImageLoader filter applied Internet Explorer can become sluggish after just a handful of alpha channel PNGs.\n\nThe other noticeable effect is that as more instances of the AlphaImageLoader are applied, the longer it takes to render the PNGs with their transparency. The user sees the PNG load in its original non-supported state (with black or grey areas where transparency should be) before one by one the filter kicks in and makes them properly transparent.\n\nBoth the issue of sluggish behaviour and delayed load only really manifest themselves with volume and size of image. Use just a couple of instances and it\u2019s fine, but be careful adding more than five or six. As ever, test, test, test.\n\nLinks become unclickable, forms unfocusable \n\nThis is a big one. There\u2019s a bug/weirdness with AlphaImageLoader that sometimes prevents interaction with links and forms when a PNG background image is used. This is sometimes reported as a z-index issue, but I don\u2019t believe it is. Rather, it\u2019s an artefact of that weird way the filter gets applied to the document almost outside of the normal render process. \n\nOften this can be solved by giving the links or form elements hasLayout using position: relative; where possible. However, this doesn\u2019t always work and the non-interaction problem cannot always be solved. You may find yourself having to go back to the drawing board.\n\nSidestepping the danger zones\n\nFrankly, it\u2019s pretty bad news if you design a site, have that design signed off by your client, build it and then find out only at the end (because you don\u2019t know what might trigger a problem) that your search field can\u2019t be focused in IE6. That\u2019s an absolute nightmare, and whilst it\u2019s not likely to happen, it\u2019s possible that it might. It\u2019s happened to me. So what can you do?\n\nThe best approach I\u2019ve found to this scenario is\n\n\n\tIsolate the PNG or PNGs that are causing the problem. Step through the PNGs in your page, commenting them out one by one and retesting. Typically it\u2019ll be the nearest PNG to the problem, so try there first. Keep going until you can click your links or focus your form fields.\n\tThis is where you really need luck on your side, because you\u2019re going to have to fake it. This will depend on the design of the site, but some way or other create a replacement GIF or JPEG image that will give you an acceptable result. Then use conditional comments to serve that image to only users of IE older than version 7.\n\n\nA hack, you say? Well, you started it chum.\n\nApplying AlphaImageLoader\n\nBecause the filter property is invalid CSS, the safest pragmatic approach is to apply it selectively with JavaScript for only Internet Explorer versions 5.5 and 6. This helps ensure that by default you\u2019re serving standard CSS to browsers that support both the CSS and PNG standards correct, and then selectively patching up only the browsers that need it. \n\nSeveral years ago, Aaron Boodman wrote and released a script called sleight for doing just that. However, sleight dealt only with images in the page, and not background images applied with CSS. Building on top of Aaron\u2019s work, I hacked sleight and came up with bgsleight for applying the filter to background images instead. That was in 2003, and over the years I\u2019ve made a couple of improvements here and there to keep it ticking over and to resolve conflicts between sleight and bgsleight when used together. However, with alpha channel PNGs becoming much more widespread, it\u2019s time for a new version.\n\nIntroducing SuperSleight\n\nSuperSleight adds a number of new and useful features that have come from the day-to-day needs of working with PNGs.\n\n\n\tWorks with both inline and background images, replacing the need for both sleight and bgsleight\n\tWill automatically apply position: relative to links and form fields if they don\u2019t already have position set. (Can be disabled.)\n\tCan be run on the entire document, or just a selected part where you know the PNGs are. This is better for performance.\n\tDetects background images set to no-repeat and sets the scaleMode to crop rather than scale.\n\tCan be re-applied by any other JavaScript in the page \u2013 useful if new content has been loaded by an Ajax request.\n\n\n Download SuperSleight \n\nImplementation\n\nGetting SuperSleight running on a page is quite straightforward, you just need to link the supplied JavaScript file (or the minified version if you prefer) into your document inside conditional comments so that it is delivered to only Internet Explorer 6 or older.\n\n\n\nSupplied with the JavaScript is a simple transparent GIF file. The script replaces the existing PNG with this before re-layering the PNG over the top using AlphaImageLoaded. You can change the name or path of the image in the top of the JavaScript file, where you\u2019ll also find the option to turn off the adding of position: relative to links and fields if you don\u2019t want that.\n\nThe script is kicked off with a call to supersleight.init() at the bottom. The scope of the script can be limited to just one part of the page by passing an ID of an element to supersleight.limitTo(). And that\u2019s all there is to it.\n\nUpdate March 2008: a version of this script as a jQuery plugin is also now available.", "year": "2007", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2007-12-01T00:00:00+00:00", "url": "https://24ways.org/2007/supersleight-transparent-png-in-ie6/", "topic": "code"} {"rowid": 166, "title": "Performance On A Shoe String", "contents": "Back in the summer, I happened to notice the official Wimbledon All England Tennis Club site had jumped to the top of Alexa\u2019s Movers & Shakers list \u2014 a list that tracks sites that have had the biggest upturn or downturn in traffic. The lawn tennis championships were underway, and so traffic had leapt from almost nothing to crazy-busy in a no time at all. \n\nMany sites have similar peaks in traffic, especially when they\u2019re based around scheduled events. No one cares about the site for most of the year, and then all of a sudden \u2013 wham! \u2013 things start getting warm in the data centre. Whilst the thought of chestnuts roasting on an open server has a certain appeal, it\u2019s less attractive if you care about your site being available to visitors. Take a look at this Alexa traffic graph showing traffic patterns for superbowl.com at the beginning of each year, and wimbledon.org in the month of July.\n\nTraffic graph from Alexa.com \n\nWhilst not on the same scale or with such dramatic peaks, we have a similar pattern of traffic here at 24ways.org. Over the last three years we\u2019ve seen a dramatic pick up in traffic over the month of December (as would be expected) and then a much lower, although steady load throughout the year. What we do have, however, is the luxury of knowing when the peaks will be. For a normal site, be that a blog, small scale web app, or even a small corporate site, you often just cannot predict when you might get slashdotted, end up on the front page of Digg or linked to from a similarly high-profile site. You just don\u2019t know when the peaks will be.\n\nIf you\u2019re a big commercial enterprise like the Super Bowl, scaling up for that traffic is simply a cost of doing business. But for most of us, we can\u2019t afford to have massive capacity sat there unused for 90% of the year. What you have to do instead is work out how to deal with as much traffic as possible with the modest resources you have.\n\nIn this article I\u2019m going to talk about some of the things we\u2019ve learned about keeping 24 ways running throughout December, whilst not spending a fortune on hosting we don\u2019t need for 11 months of each year. We\u2019ve not always got it right, but we\u2019ve learned a lot along the way.\n\nThe Problem\n\nTo know how to deal with high traffic, you need to have a basic idea of what happens when a request comes into a web server. 24 ways is hosted on a single small virtual dedicated server with a great little hosting company in the UK. We run Apache with PHP and MySQL all on that one server. When a request comes in a new Apache process is started to deal with the request (or assigned if there\u2019s one available not doing anything). Each process takes a bunch of memory, so there\u2019s a finite number of processes that you can run, and therefore a finite number of pages you can serve at once before your server runs out of memory.\n\nWith our budget based on whatever is left over after beer, we need to get best performance we can out of the resources available. As the goal is to serve as many pages as quickly as possible, there are several approaches we can take:\n\n\n\tReducing the amount of memory needed by each Apache process\n\tReducing the amount of time each process is needed\n\tReducing the number of requests made to the server\n\n\nYahoo! have published some information on what they call Exceptional Performance, which is well worth reading, and compliments many of my examples here. The Yahoo! guidelines very much look at things from a user perspective, which is always important.\n\nServer tweaking\n\nIf you\u2019re in the position of being able to change your server configuration (our set-up gives us root access to what is effectively a virtual machine) there are some basic steps you can take to maximise the available memory and reduce the memory footprint. Without getting too boring and technical (whole books have been written on this) there are a couple of things to watch out for.\n\nFirstly, check what processes you have running that you might not need. Every megabyte of memory that you free up might equate to several thousand extra requests being served each day, so take a look at top and see what\u2019s using up your resources. Quite often a machine configured as a web server will have some kind of mail server running by default. If your site doesn\u2019t use mail (ours doesn\u2019t) make sure it\u2019s shut down and not using resources.\n\nSecondly, have a look at your Apache configuration and particularly what modules are loaded. The method for doing this varies between versions of Apache, but again, every module loaded increases the amount of memory that each Apache process requires and therefore limits the number of simultaneous requests you can deal with.\n\nThe final thing to check is that Apache isn\u2019t configured to start more servers than you have memory for. This is usually done by setting the MaxClients directive. When that limit is reached, your site is going to stop responding to further requests. However, if all else goes well that threshold won\u2019t be reached, and if it does it will at least stop the weight of the traffic taking the entire server down to a point where you can\u2019t even log in to sort it out.\n\nThose are the main tidbits I\u2019ve found useful for this site, although it\u2019s worth repeating that entire books have been written on this subject alone.\n\nCaching\n\nAlthough the site is generated with PHP and MySQL, the majority of pages served don\u2019t come from the database. The process of compiling a page on-the-fly involves quite a few trips to the database for content, templates, configuration settings and so on, and so can be slow and require a lot of CPU. Unless a new article or comment is published, the site doesn\u2019t actually change between requests and so it makes sense to generate each page once, save it to a file and then just serve all following requests from that file.\n\nWe use QuickCache (or rather a plugin based on it) for this. The plugin integrates with our publishing system (Textpattern) to make sure the cache is cleared when something on the site changes. A similar plugin called WP-Cache is available for WordPress, but of course this could be done any number of ways, and with any back-end technology.\n\nThe important principal here is to reduce the time it takes to serve a page by compiling the page once and serving that cached result to subsequent visitors. Keep away from your database if you can.\n\nOutsource your feeds\n\nWe get around 36,000 requests for our feed each day. That really only works out at about 7,000 subscribers averaging five-and-a-bit requests a day, but it\u2019s still 36,000 requests we could easily do without. Each request uses resources and particularly during December, all those requests can add up. \n\nThe simple solution here was to switch our feed over to using FeedBurner. We publish the address of the FeedBurner version of our feed here, so those 36,000 requests a day hit FeedBurner\u2019s servers rather than ours. In addition, we get pretty graphs showing how the subscriber-base is building.\n\n\n\nOff-load big files\n\nLarger files like images or downloads pose a problem not in bandwidth, but in the time it takes them to transfer. A typical page request is very quick, a few seconds at the most, resulting in the connection being freed up promptly. Anything that keeps a connection open for a long time is going to start killing performance very quickly.\n\nThis year, we started serving most of the images for articles from a subdomain \u2013 media.24ways.org. Rather than pointing to our own server, this subdomain points to an Amazon S3 account where the files are held. It\u2019s easy to pigeon-hole S3 as merely an online backup solution, and whilst not a fully fledged CDN, S3 works very nicely for serving larger media files. The roughly 20GB of files served this month have cost around $5 in Amazon S3 charges. That\u2019s so affordable it may not be worth even taking the files back off S3 once December has passed.\n\nI found this article on Scalable Media Hosting with Amazon S3 to be really useful in getting started. I upload the files via a Firefox plugin (mentioned in the article) and then edit the ACL to allow public access to the files. The way S3 enables you to point DNS directly at it means that you\u2019re not tied to always using the service, and that it can be transparent to your users.\n\nIf your site uses photographs, consider uploading them to a service like Flickr and serving them directly from there. Many photo sharing sites are happy for you to link to images in this way, but do check the acceptable use policies in case you need to provide a credit or link back.\n\nOff-load small files\n\nYou\u2019ll have noticed the pattern by now \u2013 get rid of as much traffic as possible. When an article has a lot of comments and each of those comments has an avatar along with it, a great many requests are needed to fetch each of those images. In 2006 we started using Gravatar for avatars, but their servers were slow and were holding up page loads. To get around this we started caching the images on our server, but along with that came the burden of furnishing all the image requests.\n\nEarlier this year Gravatar changed hands and is now run by the same team behind WordPress.com. Those guys clearly know what they\u2019re doing when it comes to high performance, so this year we went back to serving avatars directly from them.\n\nIf your site uses avatars, it really makes sense to use a service like Gravatar where your users probably already have an account, and where the image requests are going to be dealt with for you. \n\nKnow what you\u2019re paying for\n\nThe server account we use for 24 ways was opened in November 2005. When we first hit the front page of Digg in December of that year, we upgraded the server with a bit more memory, but other than that we were still running on that 2005 spec for two years. Of course, the world of technology has moved on in those years, prices have dropped and specs have improved. For the same amount we were paying for that 2005 spec server, we could have an account with twice the CPU, memory and disk space.\n\nSo in November of this year I took out a new account and transferred the site from the old server to the new. In that single step we were prepared for dealing with twice the amount of traffic, and because of a special offer at the time I didn\u2019t even have to pay the setup cost on the new server. So it really pays to know what you\u2019re paying for and keep an eye out of ways you can make improvements without needing to spend more money.\n\nFurther steps\n\nThere\u2019s nearly always more that can be done. For example, there are some media files (particularly for older articles) that are not on S3. We also serve our CSS directly and it\u2019s not minified or compressed. But by tackling the big problems first we\u2019ve managed to reduce load on the server and at the same time make sure that the load being placed on the server can be dealt with in the most frugal way.\n\nOver the last 24 days we\u2019ve served up articles to more than 350,000 visitors without breaking a sweat. On a busy day, that\u2019s been nearly 20,000 visitors in just 24 hours. While in the grand scheme of things that\u2019s not a huge amount of traffic, it can be a lot if you\u2019re not prepared for it. However, with a little planning for the peaks you can help ensure that when the traffic arrives you\u2019re ready to capitalise on it.\n\nOf course, people only visit 24 ways for the wealth of knowledge and experience that\u2019s tied up in the articles here. Therefore I\u2019d like to take the opportunity to thank all our authors this year who have given their time as a gift to the community, and to wish you all a very happy Christmas.", "year": "2007", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2007-12-24T00:00:00+00:00", "url": "https://24ways.org/2007/performance-on-a-shoe-string/", "topic": "ux"} {"rowid": 101, "title": "Easing The Path from Design to Development", "contents": "As a web developer, I have the pleasure of working with a lot of different designers. There has been a lot of industry discussion of late about designers and developers, focusing on how different we sometimes are and how the interface between our respective phases of a project (that is to say moving from a design phase into production) can sometimes become a battleground.\n\nI don\u2019t believe it has to be a battleground. It\u2019s actually more like being a dance partner \u2013 our steps are different, but as long as we know our own part and have a little knowledge of our partner\u2019s steps, it all goes together to form a cohesive dance. Albeit with less spandex and fewer sequins (although that may depend on the project in question).\n\nAs the process usually flows from design towards development, it\u2019s most important that designers have a little knowledge of how the site is going to be built. At the specialist web development agency I\u2019m part of, we find that designs that have been well considered from a technical perspective help to keep the project on track and on budget.\n\nBased on that experience, I\u2019ve put together my checklist of things that designers should consider before handing their work over to a developer to build.\n\nLayout\n\nOne rookie mistake made by traditionally trained designers transferring to the web is to forget a web browser is not a fixed medium. Unlike designing a magazine layout or a piece of packaging, there are lots of available options to consider. Should the layout be fluid and resize with the window, or should it be set to a fixed width? If it\u2019s fluid, which parts expand and which not? If it\u2019s fixed, should it sit in the middle of the window or to one side?\n\nIf any part of the layout is going to be flexible (get wider and narrower as required), consider how any graphics are affected. Images don\u2019t usually look good if displayed at anything other that their original size, so should they behave? If a column is going to get wider than it\u2019s shown in the Photoshop comp, it may be necessary to provide separate wider versions of any background images.\n\nText size and content volume\n\nA related issue is considering how the layout behaves with both different sizes of text and different volumes of content. Whilst text zooming rather than text resizing is becoming more commonplace as the default behaviour in browsers, it\u2019s still a fundamentally important principal of web design that we are suggesting and not dictating how something should look. Designs must allow for a little give and take in the text size, and how this affects the design needs to be taken into consideration.\n\nKeep in mind that the same font can display differently in different places and platforms. Something as simple as Times will display wider on a Mac than on Windows. However, the main impact of text resizing is the change in how much vertical space copy takes up. This is particularly important where space is limited by the design (making text bigger causes many more problems than making text smaller). Each element from headings to box-outs to navigation items and buttons needs to be able to expand at least vertically, if not horizontally as well. This may require some thought about how elements on the page may wrap onto new lines, as well as again making sure to provide extended versions of any graphical elements.\n\nSimilarly, it\u2019s rare theses days to know exactly what content you\u2019re working with when a site is designed. Many, if not most sites are designed as a series of templates for some kind of content management system, and so designs cannot be tweaked around any specific item of content. Designs must be able to cope with both much greater and much lesser volumes of content that might be thrown in at the lorem ipsum phase.\n\nParticular things to watch out for are things like headings (how do they wrap onto multiple lines) and any user-generated items like usernames. It can be very easy to forget that whilst you might expect something like a username to be 8-12 characters, if the systems powering your site allow for 255 characters they\u2019ll always be someone who\u2019ll go there. Expect them to do so.\n\nAgain, if your site is content managed or not, consider the possibility that the structure might be expanded in the future. Consider how additional items might be added to each level of navigation. Whilst it\u2019s rarely desirable to make significant changes without revisiting the site\u2019s information architecture more thoroughly, it\u2019s an inevitable fact of life that the structure needs a little bit of flexibility to change over time.\n\nInteractions with and without JavaScript\n\nA great number of sites now make good use of JavaScript to streamline the user interface and make everything just that touch more usable. Remember, though, that any developer worth their salt will start by building the interface without JavaScript, get it all working, and then layer that JavaScript on top. This is to allow for users viewing the site without JavaScript available or enabled in their browser.\n\nDesigners need to consider both states of any feature they\u2019re designing \u2013 how it looks and functions with and without JavaScript. If the feature does something fancy with Ajax, consider how the same can be achieved with basic HTML forms, links and intermediary pages. These all need to be designed, because this is how some of your users will interact with the site.\n\nLogged in and logged out states\n\nWhen designing any type of web application or site that has a membership system \u2013 that is to say users can create an account and log into the site \u2013 the design will need to consider how any element is presented in both logged in and logged out states. For some items there\u2019ll be no difference, whereas for others there may be considerable differences.\n\nShould an item be hidden completely not logged out users? Should it look different in some way? Perhaps it should look the same, but prompt the user to log in when they interact with it. If so, what form should that prompt take on and how does the user progress through the authentication process to arrive back at the task they were originally trying to complete?\n\nCouple logged in and logged out states with the possible absence of JavaScript, and every feature needs to be designed in four different states:\n\n\n\tLogged out with JavaScript available\n\tLogged in with JavaScript available\n\tLogged out without JavaScript available\n\tLogged in without JavaScript available\n\n\nFonts\n\nThere are three main causes of war in this world; religions, politics and fonts. I\u2019ve said publicly before that I believe the responsibility for this falls squarely at the feet of Adobe Photoshop. Photoshop, like a mistress at a brothel, parades a vast array of ropey, yet strangely enticing typefaces past the eyes of weak, lily-livered designers, who can\u2019t help but crumble to their curvy charms.\n\nYet, on the web, we have to be a little more restrained in our choice of typefaces. The purest solution is always to make the best use of the available fonts, but this isn\u2019t always the most desirable solution from a design point of view. There are several technical solutions such as techniques that utilise Flash (like sIFR), dynamically generated images and even canvas in newer browsers. Discuss the best approach with your developer, as every different technique has different trade-offs, and this may impact the design in other ways.\n\nMessaging\n\nAny site that has interactive elements, from a simple contact form through to fully featured online software application, involves some kind of user messaging. By this I mean the error messages when something goes wrong and the success and thank-you messages when something goes right. These typically appear as the result of an interaction, so are easy to forget and miss off a Photoshop comp.\n\nFor every form, consider what gets displayed to the user if they make a mistake or miss something out, and also what gets displayed back when the interaction is successful. What do they see and where do the go next?\n\nWith Ajax interactions, the user doesn\u2019t get any visual feedback of the site waiting for a response from the server unless you design it that way. Consider using a \u2018waiting\u2019 or \u2018in progress\u2019 spinner to give the user some visual feedback of any background processes. How should these look? How do they animate?\n\nSimilarly, also consider the big error pages like a 404. With luck, these won\u2019t often be seen, but it\u2019s at the point that they are when careful design matters the most.\n\nForm fields\n\nDepending on the visual style of your site, the look of a browser\u2019s default form fields and buttons can sometimes jar. It\u2019s understandable that many a designer wants to change the way they look. Depending on the browser in question, various things can be done to style form fields and their buttons (although it\u2019s not as flexible as most would like).\n\nA common request is to replace the default buttons with a graphical button. This is usually achievable in most cases, although it\u2019s not easy to get a consistent result across all browsers \u2013 particularly when it comes to vertical positioning and the space surrounding the button. If the layout is very precise, or if space is at a premium, it\u2019s always best to try and live with the browser\u2019s default form controls.\n\nWhichever way you go, it\u2019s important to remember that in general, each form field should have a label, and each form should have a submit button. If you find that your form breaks either of those rules, you should double check.\n\nPractical tips for handing files over\n\nThere are a couple of basic steps that a design can carry out to make sure that the developer has the best chance of implementing the design exactly as envisioned.\n\nIf working with Photoshop of Fireworks or similar comping tool, it helps to group and label layers to make it easy for a developer to see which need to be turned on and off to get to isolate parts of the page and different states of the design. Also, if you don\u2019t work in the same office as your developer (and so they can\u2019t quickly check with you), provide a PDF of each page and state so that your developer can see how each page should look aside from any confusion with quick layers are switched on or off. These also act as a handy quick reference that can be used without firing up Photoshop (which can kill both productivity and your machine).\n\nFinally, provide a colour reference showing the RGB values of all the key colours used throughout the design. Without this, the developer will end up colour-picking from the comps, and could potentially end up with different colours to those you intended. Remember, for a lot of developers, working in a tool like Photoshop is like presenting a designer with an SSH terminal into a web server. It\u2019s unfamiliar ground and easy to get things wrong. Be the expert of your own domain and help your colleagues out when they\u2019re out of their comfort zone. That goes both ways.\n\nIn conclusion\n\nWhen asked the question of how to smooth hand-over between design and development, almost everyone who has experienced this situation could come up with their own list. This one is mine, based on some of the more common experiences we have at edgeofmyseat.com. So in bullet point form, here\u2019s my checklist for handing a design over.\n\n\n\tIs the layout fixed, or fluid?\n\tDoes each element cope with expanding for larger text and more content?\n\tAre all the graphics large enough to cope with an area expanding?\n\tDoes each interactive element have a state for with and without JavaScript?\n\tDoes each element have a state for logged in and logged out users?\n\tHow are any custom fonts being displayed? (and does the developer have the font to use?)\n\tDoes each interactive element have error and success messages designed?\n\tDo all form fields have a label and each form a submit button?\n\tIs your Photoshop comp document well organised?\n\tHave you provided flat PDFs of each state?\n\tHave you provided a colour reference?\n\tAre we having fun yet?", "year": "2008", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2008-12-01T00:00:00+00:00", "url": "https://24ways.org/2008/easing-the-path-from-design-to-development/", "topic": "process"} {"rowid": 181, "title": "Working With RGBA Colour", "contents": "When Tim and I were discussing the redesign of this site last year, one of the clear goals was to have a graphical style without making the pages heavy with a lot of images. When we launched, a lot of people were surprised that the design wasn\u2019t built with PNGs. Instead we\u2019d used RGBA colour values, which is part of the CSS3 specification.\n\nWhat is RGBA Colour?\n\nWe\u2019re all familiar with specifying colours in CSS using by defining the mix of red, green and blue light required to achieve our tone. This is fine and dandy, but whatever values we specify have one thing in common \u2014 the colours are all solid, flat, and well, a bit boring.\n\n Flat RGB colours\n\nCSS3 introduces a couple of new ways to specify colours, and one of those is RGBA. The A stands for Alpha, which refers to the level of opacity of the colour, or to put it another way, the amount of transparency. This means that we can set not only the red, green and blue values, but also control how much of what\u2019s behind the colour shows through. Like with layers in Photoshop.\n\nDon\u2019t We Have Opacity Already?\n\nThe ability to set the opacity on a colour differs subtly from setting the opacity on an element using the CSS opacity property. Let\u2019s look at an example.\n\nHere we have an H1 with foreground and background colours set against a page with a patterned background.\n\n Heading with no transparency applied\n\nh1 {\n\tcolor: rgb(0, 0, 0);\n\tbackground-color: rgb(255, 255, 255);\n}\n\nBy setting the CSS opacity property, we can adjust the transparency of the entire element and its contents:\n\n Heading with 50% opacity on the element\n\nh1 {\n\tcolor: rgb(0, 0, 0);\n\tbackground-color: rgb(255, 255, 255);\n\topacity: 0.5;\n}\n\nRGBA colour gives us something different \u2013 the ability to control the opacity of the individual colours rather than the entire element. So we can set the opacity on just the background:\n\n 50% opacity on just the background colour\n\nh1 {\n\tcolor: rgb(0, 0, 0);\n\tbackground-color: rgba(255, 255, 255, 0.5);\n}\n\nOr leave the background solid and change the opacity on just the text:\n\n 50% opacity on just the foreground colour\n\nh1 {\n\tcolor: rgba(0, 0, 0, 0.5);\n\tbackground-color: rgb(255, 255, 255);\n}\n\nThe How-To\n\nYou\u2019ll notice that above I\u2019ve been using the rgb() syntax for specifying colours. This is a bit less common than the usual hex codes (like #FFF) but it makes sense when starting to use RGBA. As there\u2019s no way to specify opacity with hex codes, we use rgba() like so:\n\ncolor: rgba(255, 255, 255, 0.5);\n\nJust like rgb() the first three values are red, green and blue. You can specify these 0-255 or 0%-100%. The fourth value is the opacity level from 0 (completely transparent) to 1 (completely opaque).\n\nYou can use this anywhere you\u2019d normally set a colour in CSS \u2014 so it\u2019s good for foregrounds and background, borders, outlines and so on. All the transparency effects on this site\u2019s current design are achieved this way.\n\nSupporting All Browsers\n\nLike a lot of the features we\u2019ll be looking at in this year\u2019s 24 ways, RGBA colour is supported by a lot of the newest browsers, but not the rest. Firefox, Safari, Chrome and Opera browsers all support RGBA, but Internet Explorer does not.\n\nFortunately, due to the robust design of CSS as a language, we can specify RGBA colours for browsers that support it and an alternative for browsers that do not.\n\nFalling back to solid colour\n\nThe simplest technique is to allow the browser to fall back to using a solid colour when opacity isn\u2019t available. The CSS parsing rules specify that any unrecognised value should be ignored. We can make use of this because a browser without RGBA support will treat a colour value specified with rgba() as unrecognised and discard it.\n\nSo if we specify the colour first using rgb() for all browsers, we can then overwrite it with an rgba() colour for browsers that understand RGBA.\n\nh1 {\n\tcolor: rgb(127, 127, 127);\n\tcolor: rgba(0, 0, 0, 0.5);\n}\n\nFalling back to a PNG\n\nIn cases where you\u2019re using transparency on a background-color (although not on borders or text) it\u2019s possible to fall back to using a PNG with alpha channel to get the same effect. This is less flexible than using CSS as you\u2019ll need to create a new PNG for each level of transparency required, but it can be a useful solution.\n\nUsing the same principal as before, we can specify the background in a style that all browsers will understand, and then overwrite it in a way that browsers without RGBA support will ignore.\n\nh1 {\n\tbackground: transparent url(black50.png);\n\tbackground: rgba(0, 0, 0, 0.5) none;\n}\n\nIt\u2019s important to note that this works because we\u2019re using the background shorthand property, enabling us to set both the background colour and background image in a single declaration. It\u2019s this that enables us to rely on the browser ignoring the second declaration when it encounters the unknown rgba() value.\n\nNext Steps\n\nThe really great thing about RGBA colour is that it gives us the ability to create far more graphically rich designs without the need to use images. Not only does that make for faster and lighter pages, but sites which are easier and quicker to build and maintain. CSS values can also be changed in response to user interaction or even manipulated with JavaScript in a way that\u2019s just not so easy using images.\n\n Opacity can be changed on :hover or manipulated with JavaScript\n\ndiv {\n\tcolor: rgba(255, 255, 255, 0.8);\n\tbackground-color: rgba(142, 213, 87, 0.3);\n}\ndiv:hover {\n\tcolor: rgba(255, 255, 255, 1);\n\tbackground-color: rgba(142, 213, 87, 0.6);\n}\n\nClever use of transparency in border colours can help ease the transition between overlay items and the page behind.\n\n Borders can receive the RGBA treatment, too\n\ndiv {\n\tcolor: rgb(0, 0, 0);\n\tbackground-color: rgb(255, 255, 255);\n\tborder: 10px solid rgba(255, 255, 255, 0.3);\n}\n\nIn Conclusion\n\n\nThat\u2019s a brief insight into RGBA colour, what it\u2019s good for and how it can be used whilst providing support for older browsers. With the current lack of support in Internet Explorer, it\u2019s probably not a technique that commercial designs will want to heavily rely on right away \u2013 simply because of the overhead of needing to think about fallback all the time. \n\nIt is, however, a useful tool to have for those smaller, less critical touches that can really help to finesse a design. As browser support becomes more mainstream, you\u2019ll already be familiar and practised with RGBA and ready to go.", "year": "2009", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2009-12-01T00:00:00+00:00", "url": "https://24ways.org/2009/working-with-rgba-colour/", "topic": "code"} {"rowid": 220, "title": "Finding Your Way with Static Maps", "contents": "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\u2019s first-mover advantage, and easy-to-use developer API saw Google Maps become pretty much the de facto mapping service.\n\n\n\nIt\u2019s now so easy to add a map to a web page, there\u2019s no reason not to. Dropping an iframe map into your page is as simple as embedding a YouTube video.\n\nBut there\u2019s one crucial drawback to both the solution Google provides for you to drop into your page and the code developers typically implement themselves \u2013 they don\u2019t work without JavaScript.\n\nA bit about JavaScript\n\nBack in October of this year, The Yahoo! Developer Network blog ran some tests to measure how many visitors to the Yahoo! home page didn\u2019t have JavaScript available or enabled in their browser. It\u2019s 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\u2019ll find. If there\u2019s any such thing as an \u2018average Web user\u2019 then this is them.\n\nThe results surprised me. It varied from region to region, but at most just two per cent of visitors didn\u2019t have JavaScript running. To be honest, I was expecting it to be higher, but this quote from the article caught my attention:\n\n\n\tWhile 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.\n\n\nThat\u2019s 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. \n\nSo, although a small percentage of the total, users without JavaScript can\u2019t just be forgotten about, and catering for them is at the very heart of how the web is supposed to work.\n\nStarting 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\u2019t support one of the technologies, the user still gets something they can work with. \n\nIt\u2019s progressive enhancement \u2013 also known as doing our jobs properly.\n\nSorry, wasn\u2019t this about maps?\n\nAs I was saying, the default code Google provides, and the example code it gives to developers (which typically just gets followed \u2018as is\u2019) doesn\u2019t account for users without JavaScript. No JavaScript, no content.\n\nWhen adding the ability to publish maps to our small content management system Perch, I didn\u2019t want to provide a solution that only worked with JavaScript. I had to go looking for a way to provide maps without JavaScript, too.\n\nThere\u2019s 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\u2019ve used a slippy map on a slow connection, you\u2019ll be familiar with seeing these tiles load in one by one.\n\nThe Static Map API\n\nThe 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. \n\nThis means that you can create a static, non-JavaScript version of your slippy map\u2019s 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.\n\nClearly, that\u2019s not going to be a perfect solution for every map\u2019s requirements. It doesn\u2019t 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.\n\n\n\nHere\u2019s the how\n\nRetrieving a static map tile is staggeringly easy \u2013 it\u2019s just a case of forming a URL with the correct arguments and then using that as the src of an image tag.\n\n $\"Map$ \n\nAs 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\u2019s worked with the JavaScript API.\n\n\n\tcenter determines the point on which the map is centred. This can be latitude and longitude values, or simply an address which is then geocoded.\n\tzoom sets the zoom level.\n\tsize is the pixel dimensions of the image you require.\n\tmaptype can be roadmap, satellite, terrain or hybrid.\n\tmarkers sets one or more pin locations. Markers can be labelled, have different colours, and so on \u2013 there\u2019s quite a lot of control available.\n\tsensor states whether you are using a sensor to determine the user\u2019s location. When just embedding a map in a web page, set this to false.\n\n\nThere are many options, including plotting paths and setting the image format, which can all be found in the straightforward documentation.\n\nAdding to your page\n\nIf you\u2019ve worked with the JavaScript API, you\u2019ll know that it needs a container element which you inject the map into:\n\n

\n\nAll you need to do is put your static image inside that container:\n\n

\n\nAnd then, in your JavaScript, find the image and remove it. For example, with jQuery you\u2019d simply use:\n\n$('#map img').remove();\n\nWhy not use a

element with a class applied:\n\n&\n\nA CSS rule can then be written to select the and apply a different font:\n\nspan.amp {\n font-family: Baskerville, Palatino, \"Book Antiqua\", serif;\n}\n\nThat\u2019s a perfectly serviceable technique, but the drawbacks are clear \u2014 you have to add extra markup which is borderline presentational, and you also have to be able to add that markup, which isn\u2019t always possible when working with a CMS.\n\nPerhaps we could do this with unicode-range.\n\nA better best available ampersand\n\nThe Unicode code point for an ampersand is U+26, so the ampersand font stack above can be created like so:\n\n@font-face {\n font-family: 'Ampersand';\n src: local('Baskerville'), local('Palatino'), local('Book Antiqua');\n unicode-range: U+26;\n}\n\nWhat we\u2019ve done here is specify a new family called Ampersand and created a font stack for it with the user\u2019s locally installed copies of Baskerville, Palatino or Book Antiqua. We\u2019ve then limited it to a single character range \u2014 the ampersand. Of course, those don\u2019t need to be local fonts \u2014 they could be web font files, too. If you have a font with a really snazzy ampersand, go for your life.\n\nWe can then use that new family in a regular font stack.\n\nh1 {\n font-family: Ampersand, Arial, sans-serif;\n}\n\nWith this in place, any

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\u2019t have any of the Ampersand family fonts available, the ampersand will fall back to the next item in the font stack, Arial.\n\nYou didn\u2019t think it was that easy, did you?\n\nOh, 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.\n\nIf you\u2019re familiar with how CSS works when it comes to unsupported properties, you\u2019ll know that if a browser encounters a property it doesn\u2019t implement, it just skips that declaration and moves on to the next. That works perfectly for things like border-radius \u2014 if the browser can\u2019t round off the corners, the declaration is skipped and the user sees square corners instead. Perfect.\n\nLess 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 \u2014 the whole range. If you\u2019re using a fancy font for flamboyant ampersands, you probably don\u2019t want that applied to all your text if unicode-range isn\u2019t supported. That would be bad. Really bad.\n\nEnsuring good fallbacks\n\nAs ever, the trick is to make sure that there\u2019s a sensible fallback in place if a browser doesn\u2019t have support for whatever technology you\u2019re trying to use. This is where being a super nerd about understanding the spec you\u2019re working with really pays off.\n\nWe can make use of the rules of the CSS cascade to make sure that if unicode-range isn\u2019t 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\u2019t implemented.\n\n@font-face {\n font-family: 'Ampersand';\n src: local('Baskerville'), local('Palatino'), local('Book Antiqua');\n unicode-range: U+26;\n}\n@font-face {\n font-family: 'Ampersand';\n src: local('Arial');\n}\n\nIn 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\u2019t have support, the second rule should just supersede the first, setting the font to Arial. \n\nUnfortunately, this code causes current versions of Firefox to freak out and use the first rule, applying Baskerville to the entire range. That\u2019s both unexpected and unfortunate. Bad Firefox. On your rug.\n\nIf that doesn\u2019t 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\u2019s really what we\u2019re 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\u2019re never going to use in our page? Then it wouldn\u2019t affect the outcome for browsers that do support ranges.\n\n@font-face {\n font-family: 'Ampersand';\n src: local('Baskerville'), local('Palatino'), local('Book Antiqua');\n unicode-range: U+26;\n}\n@font-face {\n /* Ampersand fallback font */\n font-family: 'Ampersand';\n src: local('Arial');\n unicode-range: U+270C;\n}\n\nBy 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\u2019re not using in any of our pages \u2014 U+270C.\n\nSo 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!\n\nThat obscure character, my friends, is what Unicode defines as the VICTORY HAND.\n\n\u270c\n\nSo, how can we use this?\n\nAmpersands are a neat trick, and it works well in browsers that support ranges, but that\u2019s not really the point of all this. Styling ampersands is fun, but they\u2019re 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.\n\nHow 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.\n\nOf course, the fact remains that browser support for unicode-range is currently limited, so any application needs to have fallbacks that you\u2019re 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\u2019ll have to use your own best judgement based on your needs and audience.\n\nOne thing to keep in mind is that if you\u2019re using web fonts, the entire font will be downloaded even if only one character is used. That said, the font shouldn\u2019t be downloaded if none of the characters within the Unicode range are present in a given page.\n\nAs 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.", "year": "2011", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2011-12-01T00:00:00+00:00", "url": "https://24ways.org/2011/creating-custom-font-stacks-with-unicode-range/", "topic": "code"} {"rowid": 80, "title": "HTML5 Video Bumpers", "contents": "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\u2019s 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.\n\nI 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.\n\nKnown as bumpers, these short introduction clips help brand a video and make it look a lot more professional.\n\n\n\nAdding bumpers to a video\n\nThe 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\u2019d need to re-edit and re-encode all your videos. Not a fun task.\n\nWhat 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.\n\nThe trade-off, of course, is that if you dynamically add your bumpers, there\u2019s 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\u2019d have no way to control the playback. As always, you need to weigh up the pros and cons and make your choice.\n\nHTML5 bumpers\n\nIf 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.\n\nMy initial thought was to treat it just like an image slideshow. If I were building a slideshow that moved between images, I\u2019d 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\u2019d use JavaScript to fade the top image out, revealing the second image beneath it.\n\n\n\nNow 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\u2019s onended event, and fade it out to reveal the main feature behind. Good idea, right?\n\nWrong\n\nRemember that this is the web. It\u2019s 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 \u2013 when you play the video, the phone often goes full-screen in its native player, leaving the web page behind. There\u2019s no opportunity to fade or switch z-index, as the video isn\u2019t being viewed in the page. Your page is left powerless. Powerless!\n\n\n\nSo what can we do? What can we control?\n\nThose of us with particularly long memories might recall a time before CSS, when we\u2019d have to use JavaScript to perform image rollovers. As CSS background images weren\u2019t a practical reality, we would use lots of elements, and perform a rollover by modifying the src attribute of the image. \n\nTurns out, this old trick of modifying the source can help us out with video, too. In most cases, modifying the src attribute of a

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