rowid,title,contents,year,author,author_slug,published,url,topic 165,Transparent PNGs in Internet Explorer 6,"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. However, there are still numbers of IE6 users out there who we can’t leave out in the cold this Christmas, so in this article I’m going to look what we can do to support IE6 users whilst taking full advantage of transparency for the majority of a site’s visitors. So what’s alpha channel transparency? Cast 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’s either fully transparent, or a solid colour. In GIF, transparency is effectively just a special colour you can chose for a pixel. The 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. This enables designers to produce images that can have, for example, soft edges without any of the ‘halo effect’ traditionally associated with GIF transparency. If you’ve ever worked on a site that has different colour schemes and therefore requires multiple versions of each graphic against a different colour, you’ll immediately see the benefit. What’s 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. The Internet Explorer problem Up 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. CSS: img { filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(...); } JavaScript: img.style.filter = ""progid:DXImageTransform.Microsoft.AlphaImageLoader(...)""; That may sound like a problem solved, but all is not as it may appear. Firstly, as you may realise, there’s no CSS property called filter in the W3C CSS spec. It’s a proprietary extension added by Microsoft that could potentially cause other browsers to reject your entire CSS rule. Secondly, 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’s because that’s precisely what it is. However, by and large the result is that PNGs with an alpha channel can be accommodated. The pitfalls So, whilst support for PNG transparency in IE5.5 and 6 is possible, it’s not without its problems. Background images cannot be positioned or repeated The 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’re 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. Delayed loading and resource use The AlphaImageLoader can be quite slow to load, and appears to consume more resources than a standard image when applied. Typically, you’d 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. The 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. Both 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’s fine, but be careful adding more than five or six. As ever, test, test, test. Links become unclickable, forms unfocusable This is a big one. There’s 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’t believe it is. Rather, it’s an artefact of that weird way the filter gets applied to the document almost outside of the normal render process. Often this can be solved by giving the links or form elements hasLayout using position: relative; where possible. However, this doesn’t always work and the non-interaction problem cannot always be solved. You may find yourself having to go back to the drawing board. Sidestepping the danger zones Frankly, it’s 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’t know what might trigger a problem) that your search field can’t be focused in IE6. That’s an absolute nightmare, and whilst it’s not likely to happen, it’s possible that it might. It’s happened to me. So what can you do? The best approach I’ve found to this scenario is Isolate 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’ll be the nearest PNG to the problem, so try there first. Keep going until you can click your links or focus your form fields. This is where you really need luck on your side, because you’re 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. A hack, you say? Well, you started it chum. Applying AlphaImageLoader Because 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’re 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. Several 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’s 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’ve 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’s time for a new version. Introducing SuperSleight SuperSleight adds a number of new and useful features that have come from the day-to-day needs of working with PNGs. Works with both inline and background images, replacing the need for both sleight and bgsleight Will automatically apply position: relative to links and form fields if they don’t already have position set. (Can be disabled.) Can be run on the entire document, or just a selected part where you know the PNGs are. This is better for performance. Detects background images set to no-repeat and sets the scaleMode to crop rather than scale. Can be re-applied by any other JavaScript in the page – useful if new content has been loaded by an Ajax request. Download SuperSleight Implementation Getting 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. Supplied 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’ll also find the option to turn off the adding of position: relative to links and fields if you don’t want that. The 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’s all there is to it. Update March 2008: a version of this script as a jQuery plugin is also now available.",2007,Drew McLellan,drewmclellan,2007-12-01T00:00:00+00:00,https://24ways.org/2007/supersleight-transparent-png-in-ie6/,code 163,Get To Grips with Slippy Maps,"Online mapping has definitely hit mainstream. Google Maps made ‘slippy maps’ popular and made it easy for any developer to quickly add a dynamic map to his or her website. You can now find maps for store locations, friends nearby, upcoming events, and embedded in blogs. In this tutorial we’ll show you how to easily add a map to your site using the Mapstraction mapping library. There are many map providers available to choose from, each with slightly different functionality, design, and terms of service. Mapstraction makes deciding which provider to use easy by allowing you to write your mapping code once, and then easily switch providers. Assemble the pieces Utilizing any of the mapping library typically consists of similar overall steps: Create an HTML div to hold the map Include the Javascript libraries Create the Javascript Map element Set the initial map center and zoom level Add markers, lines, overlays and more Create the Map Div The HTML div is where the map will actually show up on your page. It needs to have a unique id, because we’ll refer to that later to actually put the map here. This also lets you have multiple maps on a page, by creating individual divs and Javascript map elements. The size of the div also sets the height and width of the map. You set the size using CSS, either inline with the element, or via a CSS reference to the element id or class. For this example, we’ll use inline styling.
Include Javascript libraries A mapping library is like any Javascript library. You need to include the library in your page before you use the methods of that library. For our tutorial, we’ll need to include at least two libraries: Mapstraction, and the mapping API(s) we want to display. Our first example we’ll use the ubiquitous Google Maps library. However, you can just as easily include Yahoo, MapQuest, or any of the other supported libraries. Another important aspect of the mapping libraries is that many of them require an API key. You will need to agree to the terms of service, and get an API key these. Create the Map Great, we’ve now put in all the pieces we need to start actually creating our map. This is as simple as creating a new Mapstraction object with the id of the HTML div we created earlier, and the name of the mapping provider we want to use for this map. With several of the mapping libraries you will need to set the map center and zoom level before the map will appear. The map centering actually triggers the initialization of the map. var mapstraction = new Mapstraction('map','google'); var myPoint = new LatLonPoint(37.404,-122.008); mapstraction.setCenterAndZoom(myPoint, 10); A note about zoom levels. The setCenterAndZoom function takes two parameters, the center as a LatLonPoint, and a zoom level that has been defined by mapping libraries. The current usage is for zoom level 1 to be “zoomed out”, or view the entire earth – and increasing the zoom level as you zoom in. Typically 17 is the maximum zoom, which is about the size of a house. Different mapping providers have different quality of zoomed in maps over different parts of the world. This is a perfect reason why using a library like Mapstraction is very useful, because you can quickly change mapping providers to accommodate users in areas that have bad coverage with some maps. To switch providers, you just need to include the Javascript library, and then change the second parameter in the Mapstraction creation. Or, you can call the switch method to dynamically switch the provider. So for Yahoo Maps (demo): var mapstraction = new Mapstraction('map','yahoo'); or Microsoft Maps (demo): var mapstraction = new Mapstraction('map','microsoft'); want a 3D globe in your browser? try FreeEarth (demo): var mapstraction = new Mapstraction('map','freeearth'); or even OpenStreetMap (free your data!) (demo): var mapstraction = new Mapstraction('map','openstreetmap'); Visit the Mapstraction multiple map demo page for an example of how easy it is to have many maps on your page, each with a different provider. Adding Markers While adding your first map is fun, and you can probably spend hours just sliding around, the point of adding a map to your site is usually to show the location of something. So now you want to add some markers. There are a couple of ways to add to your map. The simplest is directly creating markers. You could either hard code this into a rather static page, or dynamically generate these using whatever tools your site is built on. var marker = new Marker( new LatLonPoint(37.404,-122.008) ); marker.setInfoBubble(""It's easy to add maps to your site""); mapstraction.addMarker( marker ); There is a lot more you can do with markers, including changing the icon, adding timestamps, automatically opening the bubble, or making them draggable. While it is straight-forward to create markers one by one, there is a much easier way to create a large set of markers. And chances are, you can make it very easy by extending some data you already are sharing: RSS. Specifically, using GeoRSS you can easily add a large set of markers directly to a map. GeoRSS is a community built standard (like Microformats) that added geographic markup to RSS and Atom entries. It’s as simple as adding 42 -83 to your feeds to share items via GeoRSS. Once you’ve done that, you can add that feed as an ‘overlay’ to your map using the function: mapstraction.addOverlay(""http://api.flickr.com/services/feeds/groups_pool.gne?id=322338@N20&format=rss_200&georss=1""); Mapstraction also supports KML for many of the mapping providers. So it’s easy to add various data sources together with your own data. Check out Mapufacture for a growing index of available GeoRSS feeds and KML documents. Play with your new toys Mapstraction offers a lot more functionality you can utilize for demonstrating a lot of geographic data on your website. It also includes geocoding and routing abstraction layers for making sure your users know where to go. You can see more on the Mapstraction website: http://mapstraction.com.",2007,Andrew Turner,andrewturner,2007-12-02T00:00:00+00:00,https://24ways.org/2007/get-to-grips-with-slippy-maps/,code 145,The Neverending (Background Image) Story,"Everyone likes candy for Christmas, and there’s none better than eye candy. Well, that, and just more of the stuff. Today we’re going to combine both of those good points and look at how to create a beautiful background image that goes on and on… forever! Of course, each background image is different, so instead of agonising over each and every pixel, I’m going to concentrate on five key steps that you can apply to any of your own repeating background images. In this example, we’ll look at the Miami Beach background image used on the new FOWA site, which I’m afraid is about as un-festive as you can get. 1. Choose your image wisely I find there are three main criteria when judging photos you’re considering for repetition manipulation (or ‘repetulation’, as I like to say)… simplicity (beware of complex patterns) angle and perspective (watch out for shadows and obvious vanishing points) consistent elements (for easy cloning) You might want to check out this annotated version of the image, where I’ve highlighted elements of the photo that led me to choose it as the right one. The original image purchased from iStockPhoto. The Photoshopped version used on the FOWA site. 2. The power of horizontal lines With the image chosen and your cursor poised for some Photoshop magic, the most useful thing you can do is drag out the edge pixels from one side of the image to create a kind of rough colour ‘template’ on which to work over. It doesn’t matter which side you choose, although you might find it beneficial to use the one with the simplest spread of colour and complex elements. Click and hold on the marquee tool in the toolbar and select the ‘single column marquee tool’, which will span the full height of your document but will only be one pixel wide. Make the selection right at the edge of your document, press ctrl-c / cmd-c to copy the selection you made, create a new layer, and hit ctrl-v / cmd-v to paste the selection onto your new layer. using free transform (ctrl-t / cmd-t), drag out your selection so that it becomes as wide as your entire canvas. A one-pixel-wide selection stretched out to the entire width of the canvas. 3. Cloning It goes without saying that the trusty clone tool is one of the most important in the process of creating a seamlessly repeating background image, but I think it’s important to be fairly loose with it. Always clone on to a new layer so that you’ve got the freedom to move it around, but above all else, use the eraser tool to tweak your cloned areas: let that handle the precision stuff and you won’t have to worry about getting your clones right first time. In the example below, you can see how I overcame the problem of the far-left tree shadow being chopped off by cloning the shadow from the tree on its right. The edge of the shadow is cut off and needs to be ‘made’ from a pre-existing element. The successful clone completes the missing shadow. The two elements are obviously very similar but it doesn’t look like a clone because the majority of the shape is ‘genuine’ and only a small part is a duplicate. Also, after cloning I transformed the duplicate, erased parts of it, used gradients, and — ooh, did someone mention gradients? 4. Never underestimate a gradient For this image, I used gradients in a similar way to a brush: covering large parts of the canvas with a colour that faded out to a desired point, before erasing certain parts for accuracy. Several of the gradients and brushes that make up the ‘customised’ part of the image, visible when the main photograph layer is hidden. The full composite. Gradients are also a bit of an easy fix: you can use a gradient on one side of the image, flip it horizontally, and then use it again on the opposite side to make a more seamless join. Speaking of which… 5. Sewing the seams No matter what kind of magic Photoshop dust you sprinkle over your image, there will still always be the area where the two edges meet: that scary ‘loop’ point. Fret ye not, however, for there’s help at hand in the form of a nice little cheat. Even though the loop point might still be apparent, we can help hide it by doing something to throw viewers off the scent. The seam is usually easy to spot because it’s a blank area with not much detail or colour variation, so in order to disguise it, go against the rule: put something across it! This isn’t quite as challenging as it may sound, because if we intentionally make our own ‘object’ to span the join, we can accurately measure the exact halfway point where we need to split it across the two sides of the image. This is exactly what I did with the FOWA background image: I made some clouds! A sky with no clouds in an unhappy one. A simple soft white brush creates a cloud-like formation in the sky. After taking the cloud’s opacity down to 20%, I used free transform to highlight the boundaries of the layer. I then moved it over to the right, so that the middle of the layer perfectly aligned with the right side of the canvas. Finally, I duplicated the layer and did the same in reverse: dragging the layer over to the left and making sure that the middle of the duplicate layer perfectly aligned with the left side of the canvas. And there you have it! Boom! Ta-da! Et Voila! To see the repeating background image in action, visit futureofwebapps.com on a large widescreen monitor or see a simulation of the effect. Thanks for reading, folks. Have a great Christmas!",2007,Elliot Jay Stocks,elliotjaystocks,2007-12-03T00:00:00+00:00,https://24ways.org/2007/the-neverending-background-image-story/,code 157,Capturing Caps Lock,"One of the more annoying aspects of having to remember passwords (along with having to remember loads of them) is that if you’ve got Caps Lock turned on accidentally when you type one in, it won’t work, and you won’t know why. Most desktop computers alert you in some way if you’re trying to enter your password to log on and you’ve enabled Caps Lock; there’s no reason why the web can’t do the same. What we want is a warning – maybe the user wants Caps Lock on, because maybe their password is in capitals – rather than something that interrupts what they’re doing. Something subtle. But that doesn’t answer the question of how to do it. Sadly, there’s no way of actually detecting whether Caps Lock is on directly. However, there’s a simple work-around; if the user presses a key, and it’s a capital letter, and they don’t have the Shift key depressed, why then they must have Caps Lock on! Simple. DOM scripting allows your code to be notified when a key is pressed in an element; when the key is pressed, you get the ASCII code for that key. Capital letters, A to Z, have ASCII codes 65 to 90. So, the code would look something like: on a key press if the ASCII code for the key is between 65 and 90 *and* if shift is pressed warn the user that they have Caps Lock on, but let them carry on end if end keypress The actual JavaScript for this is more complicated, because both event handling and keypress information differ across browsers. Your event handling functions are passed an event object, except in Internet Explorer where you use the global event object; the event object has a which parameter containing the ASCII code for the key pressed, except in Internet Explorer where the event object has a keyCode parameter; some browsers store whether the shift key is pressed in a shiftKey parameter and some in a modifiers parameter. All this boils down to code that looks something like this: keypress: function(e) { var ev = e ? e : window.event; if (!ev) { return; } var targ = ev.target ? ev.target : ev.srcElement; // get key pressed var which = -1; if (ev.which) { which = ev.which; } else if (ev.keyCode) { which = ev.keyCode; } // get shift status var shift_status = false; if (ev.shiftKey) { shift_status = ev.shiftKey; } else if (ev.modifiers) { shift_status = !!(ev.modifiers & 4); } // At this point, you have the ASCII code in “which”, // and shift_status is true if the shift key is pressed } Then it’s just a check to see if the ASCII code is between 65 and 90 and the shift key is pressed. (You also need to do the same work if the ASCII code is between 97 (a) and 122 (z) and the shift key is not pressed, because shifted letters are lower-case if Caps Lock is on.) if (((which >= 65 && which <= 90) && !shift_status) || ((which >= 97 && which <= 122) && shift_status)) { // uppercase, no shift key /* SHOW THE WARNING HERE */ } else { /* HIDE THE WARNING HERE */ } The warning can be implemented in many different ways: highlight the password field that the user is typing into, show a tooltip, display text next to the field. For simplicity, this code shows the warning as a previously created image, with appropriate alt text. Showing the warning means creating a new tag with DOM scripting, dropping it into the page, and positioning it so that it’s next to the appropriate field. The image looks like this: You know the position of the field the user is typing into (from its offsetTop and offsetLeft properties) and how wide it is (from its offsetWidth properties), so use createElement to make the new img element, and then absolutely position it with style properties so that it appears in the appropriate place (near to the text field). The image is a transparent PNG with an alpha channel, so that the drop shadow appears nicely over whatever else is on the page. Because Internet Explorer version 6 and below doesn’t handle transparent PNGs correctly, you need to use the AlphaImageLoader technique to make the image appear correctly. newimage = document.createElement('img'); newimage.src = ""http://farm3.static.flickr.com/2145/2067574980_3ddd405905_o_d.png""; newimage.style.position = ""absolute""; newimage.style.top = (targ.offsetTop - 73) + ""px""; newimage.style.left = (targ.offsetLeft + targ.offsetWidth - 5) + ""px""; newimage.style.zIndex = ""999""; newimage.setAttribute(""alt"", ""Warning: Caps Lock is on""); if (newimage.runtimeStyle) { // PNG transparency for IE newimage.runtimeStyle.filter += ""progid:DXImageTransform.Microsoft.AlphaImageLoader(src='http://farm3.static.flickr.com/2145/2067574980_3ddd405905_o_d.png',sizingMethod='scale')""; } document.body.appendChild(newimage); Note that the alt text on the image is also correctly set. Next, all these parts need to be pulled together. On page load, identify all the password fields on the page, and attach a keypress handler to each. (This only needs to be done for password fields because the user can see if Caps Lock is on in ordinary text fields.) var inps = document.getElementsByTagName(""input""); for (var i=0, l=inps.length; i The “create an image” code from above should only be run if the image is not already showing, so instead of creating a newimage object, create the image and attach it to the password field so that it can be checked for later (and not shown if it’s already showing). For safety, all the code should be wrapped up in its own object, so that its functions don’t collide with anyone else’s functions. So, create a single object called capslock and make all the functions be named methods of the object: var capslock = { ... keypress: function(e) { } ... } Also, the “create an image” code is saved into its own named function, show_warning(), and the converse “remove the image” code into hide_warning(). This has the advantage that developers can include the JavaScript library that has been written here, but override what actually happens with their own code, using something like: And that’s all. Simply include the JavaScript library in your pages, override what happens on a warning if that’s more appropriate for what you’re doing, and that’s all you need. See the script in action.",2007,Stuart Langridge,stuartlangridge,2007-12-04T00:00:00+00:00,https://24ways.org/2007/capturing-caps-lock/,code 164,My Other Christmas Present Is a Definition List,"A note from the editors: readers should note that the HTML5 redefinition of definition lists has come to pass and is now à la mode. Last year, I looked at how the markup for tag clouds was generally terrible. I thought this year I would look not at a method of marking up a common module, but instead just at a simple part of HTML and how it generally gets abused. No, not tables. Definition lists. Ah, definition lists. Often used but rarely understood. Examining the definition of definitions To start with, let’s see what the HTML spec has to say about them. Definition lists vary only slightly from other types of lists in that list items consist of two parts: a term and a description. The canonical example of a definition list is a dictionary. Words can have multiple descriptions (even the word definition has at least five). Also, many terms can share a single definition (for example, the word colour can also be spelt color, but they have the same definition). Excellent, we can all grasp that. But it very quickly starts to fall apart. Even in the HTML specification the definition list is mis-used. Another application of DL, for example, is for marking up dialogues, with each DT naming a speaker, and each DD containing his or her words. Wrong. Completely and utterly wrong. This is the biggest flaw in the HTML spec, along with dropping support for the start attribute on ordered lists. “Why?”, you may ask. Let me give you an example from Romeo and Juliet, act 2, scene 2.
Juliet
Romeo!
Romeo
My niesse?
Juliet
At what o'clock tomorrow shall I send to thee?
Romeo
At the hour of nine.
Now, the problem here is that a given definition can have multiple descriptions (the DD). Really the dialog “descriptions” should be rolled up under the terms, like so:
Juliet
Romeo!
At what o'clock tomorrow shall I send to thee?
Romeo
My niesse?
At the hour of nine.
Suddenly the play won’t make anywhere near as much sense. (If it’s anything, the correct markup for a play is an ordered list of CITE and BLOCKQUOTE elements.) This is the first part of the problem. That simple example has turned definition lists in everyone’s mind from pure definitions to more along the lines of a list with pre-configured heading(s) and text(s). Screen reader, enter stage left. In many screen readers, a simple definition list would be read out as “definition term equals definition description”. So in our play excerpt, Juliet equals Romeo! That’s not right, either. But this also leads a lot of people astray with definition lists to believing that they are useful for key/value pairs. Behaviour and convention The WHAT-WG have noticed the common mis-use of the DL, and have codified it into the new spec. In the HTML5 draft, a definition list is no longer a definition list. The dl element introduces an unordered association list consisting of zero or more name-value groups (a description list). Each group must consist of one or more names (dt elements) followed by one or more values (dd elements). They also note that the “dl element is inappropriate for marking up dialogue, since dialogue is ordered”. So for that example they have created a DIALOG (sic) element. Strange, then, that they keep DL as-is but instead refer to it an “association list”. They have not created a new AL element, and kept DL for the original purpose. They have chosen not to correct the usage or to create a new opportunity for increased specificity in our HTML, but to “pave the cowpath” of convention. How to use a definition list Given that everyone else is using a DL incorrectly, should we? Well, if they all jumped off a bridge, would you too? No, of course you wouldn’t. We don’t have HTML5 yet, so we’re stuck with the existing semantics of HTML4 and XHTML1. Which means that: Listing dialogue is not defining anything. Listing the attributes of a piece of hardware (resolution = 1600×1200) is illustrating sample values, not defining anything (however, stating what ‘resolution’ actually means in this context would be a definition). Listing the cast and crew of a given movie is not defining the people involved in making movies. (Stuart Gordon may have been the director of Space Truckers, but that by no means makes him the true definition of a director.) A menu of navigation items is simply a nested ordered or unordered list of links, not a definition list. Applying styling handles to form labels and elements is not a good use for a definition list. And so on. Living by the specification, a definition list should be used for term definitions – glossaries, lexicons and dictionaries – only. Anything else is a crime against markup.",2007,Mark Norman Francis,marknormanfrancis,2007-12-05T00:00:00+00:00,https://24ways.org/2007/my-other-christmas-present-is-a-definition-list/,code 153,JavaScript Internationalisation,"or: Why Rudolph Is More Than Just a Shiny Nose Dunder sat, glumly staring at the computer screen. “What’s up, Dunder?” asked Rudolph, entering the stable and shaking off the snow from his antlers. “Well,” Dunder replied, “I’ve just finished coding the new reindeer intranet Santa Claus asked me to do. You know how he likes to appear to be at the cutting edge, talking incessantly about Web 2.0, AJAX, rounded corners; he even spooked Comet recently by talking about him as if he were some pushy web server. “I’ve managed to keep him happy, whilst also keeping it usable, accessible, and gleaming — and I’m still on the back row of the sleigh! But anyway, given the elves will be the ones using the site, and they come from all over the world, the site is in multiple languages. Which is great, except when it comes to the preview JavaScript I’ve written for the reindeer order form. Here, have a look…” As he said that, he brought up the textileRef:8234272265470b85d91702:linkStartMarker:“order form in French”:/examples/javascript-internationalisation/initial.fr.html on the screen. (Same in English). “Looks good,” said Rudolph. “But if I add some items,” said Dunder, “the preview appears in English, as it’s hard-coded in the JavaScript. I don’t want separate code for each language, as that’s just silly — I thought about just having if statements, but that doesn’t scale at all…” “And there’s more, you aren’t displaying large numbers in French properly, either,” added Rudolph, who had been playing and looking at part of the source code: function update_text() { var hay = getValue('hay'); var carrots = getValue('carrots'); var bells = getValue('bells'); var total = 50 * bells + 30 * hay + 10 * carrots; var out = 'You are ordering ' + pretty_num(hay) + ' bushel' + pluralise(hay) + ' of hay, ' + pretty_num(carrots) + ' carrot' + pluralise(carrots) + ', and ' + pretty_num(bells) + ' shiny bell' + pluralise(bells) + ', at a total cost of ' + pretty_num(total) + ' gold pieces. Thank you.'; document.getElementById('preview').innerHTML = out; } function pretty_num(n) { n += ''; var o = ''; for (i=n.length; i>3; i-=3) { o = ',' + n.slice(i-3, i) + o; } o = n.slice(0, i) + o; return o; } function pluralise(n) { if (n!=1) return 's'; return ''; } “Oh, botheration!” cried Dunder. “This is just so complicated.” “It doesn’t have to be,” said Rudolph, “you just have to think about things in a slightly different way from what you’re used to. As we’re only a simple example, we won’t be able to cover all possibilities, but for starters, we need some way of providing different information to the script dependent on the language. We’ll create a global i18n object, say, and fill it with the correct language information. The first variable we’ll need will be a thousands separator, and then we can change the pretty_num function to use that instead: function pretty_num(n) { n += ''; var o = ''; for (i=n.length; i>3; i-=3) { o = i18n.thousands_sep + n.slice(i-3, i) + o; } o = n.slice(0, i) + o; return o; } “The i18n object will also contain our translations, which we will access through a function called _() — that’s just an underscore. Other languages have a function of the same name doing the same thing. It’s very simple: function _(s) { if (typeof(i18n)!='undefined' && i18n[s]) { return i18n[s]; } return s; } “So if a translation is available and provided, we’ll use that; otherwise we’ll default to the string provided — which is helpful if the translation begins to lag behind the site’s text at all, as at least something will be output.” “Got it,” said Dunder. “ _('Hello Dunder') will print the translation of that string, if one exists, ‘Hello Dunder’ if not.” “Exactly. Moving on, your plural function breaks even in English if we have a word where the plural doesn’t add an s — like ‘children’.” “You’re right,” said Dunder. “How did I miss that?” “No harm done. Better to provide both singular and plural words to the function and let it decide which to use, performing any translation as well: function pluralise(s, p, n) { if (n != 1) return _(p); return _(s); } “We’d have to provide different functions for different languages as we employed more elves and got more complicated — for example, in Polish, the word ‘file’ pluralises like this: 1 plik, 2-4 pliki, 5-21 plików, 22-24 pliki, 25-31 plików, and so on.” (More information on plural forms) “Gosh!” “Next, as different languages have different word orders, we must stop using concatenation to construct sentences, as it would be impossible for other languages to fit in; we have to keep coherent strings together. Let’s rewrite your update function, and then go through it: function update_text() { var hay = getValue('hay'); var carrots = getValue('carrots'); var bells = getValue('bells'); var total = 50 * bells + 30 * hay + 10 * carrots; hay = sprintf(pluralise('%s bushel of hay', '%s bushels of hay', hay), pretty_num(hay)); carrots = sprintf(pluralise('%s carrot', '%s carrots', carrots), pretty_num(carrots)); bells = sprintf(pluralise('%s shiny bell', '%s shiny bells', bells), pretty_num(bells)); var list = sprintf(_('%s, %s, and %s'), hay, carrots, bells); var out = sprintf(_('You are ordering %s, at a total cost of %s gold pieces.'), list, pretty_num(total)); out += ' '; out += _('Thank you.'); document.getElementById('preview').innerHTML = out; } “ sprintf is a function in many other languages that, given a format string and some variables, slots the variables into place within the string. JavaScript doesn’t have such a function, so we’ll write our own. Again, keep it simple for now, only integers and strings; I’m sure more complete ones can be found on the internet. function sprintf(s) { var bits = s.split('%'); var out = bits[0]; var re = /^([ds])(.*)$/; for (var i=1; i%s gold pieces."": '', ""Thank you."": '' }; “If you implement this across the intranet, you’ll want to investigate the xgettext program, which can automatically extract all strings that need translating from all sorts of code files into a standard .po file (I think Python mode works best for JavaScript). You can then use a different program to take the translated .po file and automatically create the language-specific JavaScript files for us.” (e.g. German .po file for PledgeBank, mySociety’s .po-.js script, example output) With a flourish, Rudolph finished editing. “And there we go, localised JavaScript in English, French, or German, all using the same main code.” “Thanks so much, Rudolph!” said Dunder. “I’m not just a pretty nose!” Rudolph quipped. “Oh, and one last thing — please comment liberally explaining the context of strings you use. Your translator will thank you, probably at the same time as they point out the four hundred places you’ve done something in code that only works in your language and no-one else’s…” Thanks to Tim Morley and Edmund Grimley Evans for the French and German translations respectively.",2007,Matthew Somerville,matthewsomerville,2007-12-08T00:00:00+00:00,https://24ways.org/2007/javascript-internationalisation/,code 168,Unobtrusively Mapping Microformats with jQuery,"Microformats are everywhere. You can’t shake an electronic stick these days without accidentally poking a microformat-enabled site, and many developers use microformats as a matter of course. And why not? After all, why invent your own class names when you can re-use pre-defined ones that give your site extra functionality for free? Nevertheless, while it’s good to know that users of tools such as Tails and Operator will derive added value from your shiny semantics, it’s nice to be able to reuse that effort in your own code. We’re going to build a map of some of my favourite restaurants in Brighton. Fitting with the principles of unobtrusive JavaScript, we’ll start with a semantically marked up list of restaurants, then use JavaScript to add the map, look up the restaurant locations and plot them as markers. We’ll be using a couple of powerful tools. The first is jQuery, a JavaScript library that is ideally suited for unobtrusive scripting. jQuery allows us to manipulate elements on the page based on their CSS selector, which makes it easy to extract information from microformats. The second is Mapstraction, introduced here by Andrew Turner a few days ago. We’ll be using Google Maps in the background, but Mapstraction makes it easy to change to a different provider if we want to later. Getting Started We’ll start off with a simple collection of microformatted restaurant details, representing my seven favourite restaurants in Brighton. The full, unstyled list can be seen in restaurants-plain.html. Each restaurant listing looks like this:

  • Riddle & Finns

    12b Meeting House Lane

    Brighton, UK

    BN1 1HB

    Telephone: +44 (0)1273 323 008

    E-mail: info@riddleandfinns.co.uk

    • Since we’re dealing with a list of restaurants, each hCard is marked up inside a list item. Each restaurant is an organisation; we signify this by placing the classes fn and org on the element surrounding the restaurant’s name (according to the hCard spec, setting both fn and org to the same value signifies that the hCard represents an organisation rather than a person). The address information itself is contained within a div of class adr. Note that the HTML
    element is not suitable here for two reasons: firstly, it is intended to mark up contact details for the current document rather than generic addresses; secondly, address is an inline element and as such cannot contain the paragraphs elements used here for the address information. A nice thing about microformats is that they provide us with automatic hooks for our styling. For the moment we’ll just tidy up the whitespace a bit; for more advanced style tips consult John Allsop’s guide from 24 ways 2006. .vcard p { margin: 0; } .adr { margin-bottom: 0.5em; } To plot the restaurants on a map we’ll need latitude and longitude for each one. We can find this out from their address using geocoding. Most mapping APIs include support for geocoding, which means we can pass the API an address and get back a latitude/longitude point. Mapstraction provides an abstraction layer around these APIs which can be included using the following script tag: While we’re at it, let’s pull in the other external scripts we’ll be using: That’s everything set up: let’s write some JavaScript! In jQuery, almost every operation starts with a call to the jQuery function. The function simulates method overloading to behave in different ways depending on the arguments passed to it. When writing unobtrusive JavaScript it’s important to set up code to execute when the page has loaded to the point that the DOM is available to be manipulated. To do this with jQuery, pass a callback function to the jQuery function itself: jQuery(function() { // This code will be executed when the DOM is ready }); Initialising the map The first thing we need to do is initialise our map. Mapstraction needs a div with an explicit width, height and ID to show it where to put the map. Our document doesn’t currently include this markup, but we can insert it with a single line of jQuery code: jQuery(function() { // First create a div to host the map var themap = jQuery('
    ').css({ 'width': '90%', 'height': '400px' }).insertBefore('ul.restaurants'); }); While this is technically just a single line of JavaScript (with line-breaks added for readability) it’s actually doing quite a lot of work. Let’s break it down in to steps: var themap = jQuery('
    ') Here’s jQuery’s method overloading in action: if you pass it a string that starts with a < it assumes that you wish to create a new HTML element. This provides us with a handy shortcut for the more verbose DOM equivalent: var themap = document.createElement('div'); themap.id = 'themap'; Next we want to apply some CSS rules to the element. jQuery supports chaining, which means we can continue to call methods on the object returned by jQuery or any of its methods: var themap = jQuery('
    ').css({ 'width': '90%', 'height': '400px' }) Finally, we need to insert our new HTML element in to the page. jQuery provides a number of methods for element insertion, but in this case we want to position it directly before the