{"rowid": 314, "title": "Easy Ajax with Prototype", "contents": "There\u2019s little more impressive on the web today than a appropriate touch of Ajax. Used well, Ajax brings a web interface much closer to the experience of a desktop app, and can turn a bear of an task into a pleasurable activity.\n\nBut it\u2019s really hard, right? It involves all the nasty JavaScript that no one ever does often enough to get really good at, and the browser support is patchy, and urgh it\u2019s just so much damn effort. Well, the good news is that \u2013 ta-da \u2013 it doesn\u2019t have to be a headache. But man does it still look impressive. Here\u2019s how to amaze your friends.\n\nIntroducing prototype.js\n\nPrototype is a JavaScript framework by Sam Stephenson designed to help make developing dynamic web apps a whole lot easier. In basic terms, it\u2019s a JavaScript file which you link into your page that then enables you to do cool stuff.\n\nThere\u2019s loads of capability built in, a portion of which covers our beloved Ajax. The whole thing is freely distributable under an MIT-style license, so it\u2019s good to go. What a nice man that Mr Stephenson is \u2013 friends, let us raise a hearty cup of mulled wine to his good name. Cheers! sluurrrrp.\n\nFirst step is to download the latest Prototype and put it somewhere safe. I suggest underneath the Christmas tree.\n\nCutting to the chase\n\nBefore I go on and set up an example of how to use this, let\u2019s just get to the crux. Here\u2019s how Prototype enables you to make a simple Ajax call and dump the results back to the page:\n\nvar url = 'myscript.php';\nvar pars = 'foo=bar';\nvar target = 'output-div';\t\nvar myAjax = new Ajax.Updater(target, url, {method: 'get', parameters: pars});\n\nThis snippet of JavaScript does a GET to myscript.php, with the parameter foo=bar, and when a result is returned, it places it inside the element with the ID output-div on your page.\n\nKnocking up a basic example\n\nSo to get this show on the road, there are three files we need to set up in our site alongside prototype.js. Obviously we need a basic HTML page with prototype.js linked in. This is the page the user interacts with. Secondly, we need our own JavaScript file for the glue between the interface and the stuff Prototype is doing. Lastly, we need the page (a PHP script in my case) that the Ajax is going to make its call too.\n\nSo, to that basic HTML page for the user to interact with. Here\u2019s one I found whilst out carol singing:\n\n\n\n\n \n Easy Ajax\n \n \n \n\n
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\n \n \n \n
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\n
\n\n\n\nAs you can see, I\u2019ve linked in prototype.js, and also a file called ajax.js, which is where we\u2019ll be putting our glue. (Careful where you leave your glue, kids.)\n\nOur basic example is just going to take a name and then echo it back in the form of a seasonal greeting. There\u2019s a form with an input field for a name, and crucially a DIV (greeting) for the result of our call. You\u2019ll also notice that the form has a submit button \u2013 this is so that it can function as a regular form when no JavaScript is available. It\u2019s important not to get carried away and forget the basics of accessibility.\n\nMeanwhile, back at the server\n\nSo we need a script at the server which is going to take input from the Ajax call and return some output. This is normally where you\u2019d hook into a database and do whatever transaction you need to before returning a result. To keep this as simple as possible, all this example here will do is take the name the user has given and add it to a greeting message. Not exactly Web 2-point-HoHoHo, but there you have it.\n\nHere\u2019s a quick PHP script \u2013 greeting.php \u2013 that Santa brought me early.\n\nSeason's Greetings, $the_name!

\";\n?>\n\nYou\u2019ll perhaps want to do something a little more complex within your own projects. Just sayin\u2019.\n\nGluing it all together\n\nInside our ajax.js file, we need to hook this all together. We\u2019re going to take advantage of some of the handy listener routines and such that Prototype also makes available. The first task is to attach a listener to set the scene once the window has loaded. He\u2019s how we attach an onload event to the window object and get it to call a function named init():\n\nEvent.observe(window, 'load', init, false);\n\nNow we create our init() function to do our evil bidding. Its first job of the day is to hide the submit button for those with JavaScript enabled. After that, it attaches a listener to watch for the user typing in the name field.\n\nfunction init(){\n $('greeting-submit').style.display = 'none';\n Event.observe('greeting-name', 'keyup', greet, false);\n}\n\nAs you can see, this is going to make a call to a function called greet() onkeyup in the greeting-name field. That function looks like this:\n\nfunction greet(){\n var url = 'greeting.php';\n var pars = 'greeting-name='+escape($F('greeting-name'));\n var target = 'greeting';\n var myAjax = new Ajax.Updater(target, url, {method: 'get', parameters: pars});\n}\n\nThe key points to note here are that any user input needs to be escaped before putting into the parameters so that it\u2019s URL-ready. The target is the ID of the element on the page (a DIV in our case) which will be the recipient of the output from the Ajax call.\n\nThat\u2019s it\n\nNo, seriously. That\u2019s everything. Try the example. Amaze your friends with your 1337 Ajax sk1llz.", "year": "2005", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2005-12-01T00:00:00+00:00", "url": "https://24ways.org/2005/easy-ajax-with-prototype/", "topic": "code"} {"rowid": 315, "title": "Edit-in-Place with Ajax", "contents": "Back on day one we looked at using the Prototype library to take all the hard work out of making a simple Ajax call. While that was fun and all, it didn\u2019t go that far towards implementing something really practical. We dipped our toes in, but haven\u2019t learned to swim yet.\n\nSo here is swimming lesson number one. Anyone who\u2019s used Flickr to publish their photos will be familiar with the edit-in-place system used for quickly amending titles and descriptions on photographs. Hovering over an item turns its background yellow to indicate it is editable. A simple click loads the text into an edit box, right there on the page.\n\n\n\nPrototype includes all sorts of useful methods to help reproduce something like this for our own projects. As well as the simple Ajax GETs we learned how to do last time, we can also do POSTs (which we\u2019ll need here) and a whole bunch of manipulations to the user interface \u2013 all through simple library calls. Here\u2019s what we\u2019re building, so let\u2019s do it.\n\nGetting Started\n\nThere are two major components to this process; the user interface manipulation and the Ajax call itself. Our set-up is much the same as last time (you may wish to read the first article if you\u2019ve not already done so). We have a basic HTML page which links in the prototype.js file and our own editinplace.js. Here\u2019s what Santa dropped down my chimney: \n\n\n \n \n \n Edit-in-Place with Ajax\n \n \n \n \n\n

Edit-in-place

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Dashing through the snow on a one horse open sleigh.

\n \n \n\nSo that\u2019s our page. The editable item is going to be the

called desc. The process goes something like this:\n\n\n\tHighlight the area onMouseOver\n\tClear the highlight onMouseOut\n\tIf the user clicks, hide the area and replace with a ';\n\n var button = ' OR \n ';\n\n new Insertion.After(obj, textarea+button);\n\n Event.observe(obj.id+'_save', 'click', function(){saveChanges(obj)}, false);\n Event.observe(obj.id+'_cancel', 'click', function(){cleanUp(obj)}, false);\n\n }\n\nThe first thing to do is to hide the object. Prototype comes to the rescue with Element.hide() (and of course, Element.show() too). Following that, we build up the textarea and buttons as a string, and then use Insertion.After() to place our new editor underneath the (now hidden) editable object.\n\nThe last thing to do before we leave the user to edit is it attach listeners to the Save and Cancel buttons to call either the saveChanges() function, or to cleanUp() after a cancel.\n\nIn the event of a cancel, we can clean up behind ourselves like so:\n\nfunction cleanUp(obj, keepEditable){\n Element.remove(obj.id+'_editor');\n Element.show(obj);\n if (!keepEditable) showAsEditable(obj, true);\n }\n\nSaving the Changes\n\nThis is where all the Ajax fun occurs. Whilst the previous article introduced Ajax.Updater() for simple Ajax calls, in this case we need a little bit more control over what happens once the response is received. For this purpose, Ajax.Request() is perfect. We can use the onSuccess and onFailure parameters to register functions to handle the response.\n\nfunction saveChanges(obj){\n var new_content = escape($F(obj.id+'_edit'));\n\n obj.innerHTML = \"Saving...\";\n cleanUp(obj, true);\n\n var success = function(t){editComplete(t, obj);}\n var failure = function(t){editFailed(t, obj);}\n\n var url = 'edit.php';\n var pars = 'id=' + obj.id + '&content=' + new_content;\n var myAjax = new Ajax.Request(url, {method:'post',\n postBody:pars, onSuccess:success, onFailure:failure});\n }\n\n function editComplete(t, obj){\n obj.innerHTML = t.responseText;\n showAsEditable(obj, true);\n }\n\n function editFailed(t, obj){\n obj.innerHTML = 'Sorry, the update failed.';\n cleanUp(obj);\n }\n\nAs you can see, we first grab in the contents of the textarea into the variable new_content. We then remove the editor, set the content of the original object to \u201cSaving\u2026\u201d to show that an update is occurring, and make the Ajax POST.\n\nIf the Ajax fails, editFailed() sets the contents of the object to \u201cSorry, the update failed.\u201d Admittedly, that\u2019s not a very helpful way to handle the error but I have to limit the scope of this article somewhere. It might be a good idea to stow away the original contents of the object (obj.preUpdate = obj.innerHTML) for later retrieval before setting the content to \u201cSaving\u2026\u201d. No one likes a failure \u2013 especially a messy one.\n\nIf the Ajax call is successful, the server-side script returns the edited content, which we then place back inside the object from editComplete, and tidy up.\n\nMeanwhile, back at the server\n\nThe missing piece of the puzzle is the server-side script for committing the changes to your database. Obviously, any solution I provide here is not going to fit your particular application. For the purposes of getting a functional demo going, here\u2019s what I have in PHP.\n\n\n\nNot exactly rocket science is it? I\u2019m just catching the content item from the POST and echoing it back. For your application to be useful, however, you\u2019ll need to know exactly which record you should be updating. I\u2019m passing in the ID of my

, 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": 318, "title": "Auto-Selecting Navigation", "contents": "In the article Centered Tabs with CSS Ethan laid out a tabbed navigation system which can be centred on the page. A frequent requirement for any tab-based navigation is to be able to visually represent the currently selected tab in some way.\n\nIf you\u2019re using a server-side language such as PHP, it\u2019s quite easy to write something like class=\"selected\" into your markup, but it can be even simpler than that.\n\nLet\u2019s take the navigation div from Ethan\u2019s article as an example.\n\n
\n \n
\n\nAs you can see we have a standard unordered list which is then styled with CSS to look like tabs. By giving each tab a class which describes it\u2019s logical section of the site, if we were to then apply a class to the body tag of each page showing the same, we could write a clever CSS selector to highlight the correct tab on any given page. \n\nSound complicated? Well, it\u2019s not a trivial concept, but actually applying it is dead simple.\n\nModifying the markup\n\nFirst thing is to place a class name on each li in the list:\n\n
\n \n
\n\nThen, on each page of your site, apply the a matching class to the body tag to indicate which section of the site that page is in. For example, on your About page:\n\n...\n\nWriting the CSS selector\n\nYou can now write a single CSS rule to match the selected tab on any given page. The logic is that you want to match the \u2018about\u2019 tab on the \u2018about\u2019 page and the \u2018products\u2019 tab on the \u2018products\u2019 page, so the selector looks like this:\n\nbody.home #navigation li.home,\n body.about #navigation li.about,\n body.work #navigation li.work,\n body.products #navigation li.products,\n body.contact #navigation li.contact{\n ... whatever styles you need to show the tab selected ...\n } \n\nSo all you need to do when you create a new page in your site is to apply a class to the body tag to say which section it\u2019s in. The CSS will do the rest for you \u2013 without any server-side help.", "year": "2005", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2005-12-10T00:00:00+00:00", "url": "https://24ways.org/2005/auto-selecting-navigation/", "topic": "code"} {"rowid": 336, "title": "Practical Microformats with hCard", "contents": "You\u2019ve probably heard about microformats over the last few months. You may have even read the easily digestible introduction at Digital Web Magazine, but perhaps you\u2019ve not found time to actually implement much yet. That\u2019s understandable, as it can sometimes be difficult to see exactly what you\u2019re adding by applying a microformat to a page. Sure, you\u2019re semantically enhancing the information you\u2019re marking up, and the Semantic Web is a great idea and all, but what benefit is it right now, today? \n\nWell, the answer to that question is simple: you\u2019re adding lots of information that can be and is being used on the web here and now. The big ongoing battle amongst the big web companies if one of territory over information. Everyone\u2019s grasping for as much data as possible. Some of that information many of us are cautious to give away, but a lot of is happy to be freely available. Of the data you\u2019re giving away, it makes sense to give it as much meaning as possible, thus enabling anyone from your friends and family to the giant search company down the road to make the most of it.\n\nOk, enough of the waffle, let\u2019s get working.\n\nIntroducing hCard\n\nYou may have come across hCard. It\u2019s a microformat for describing contact information (or really address book information) from within your HTML. It\u2019s based on the vCard format, which is the format the contacts/address book program on your computer uses. All the usual fields are available \u2013 name, address, town, website, email, you name it.\n\nIf you\u2019re running Firefox and Greasemonkey (or if you can, just to try this out), install this user script. What it does is look for instances of the hCard microformat in a page, and then add in a link to pass any hCards it finds to a web service which will convert it to a vCard. Take a look at the About the author box at the bottom of this article. It\u2019s a hCard, so you should be able to click the icon the user script inserts and add me to your Outlook contacts or OS X Address Book with just a click.\n\nSo microformats are useful after all. Free microformats all round!\n\nImplementing hCard\n\nThis is the really easy bit. All the hCard microformat is, is a bunch of predefined class names that you apply to the markup you\u2019ve probably already got around your contact information. Let\u2019s take the example of the About the author box from this article. Here\u2019s how the markup looks without hCard:\n\n
\n

About the author

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Drew McLellan is a web developer, author and no-good swindler from \n just outside London, England. At the \n Web Standards Project he works \n on press, strategy and tools. Drew keeps a \n personal weblog covering web \n development issues and themes.

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\n\nThis is a really simple example because there\u2019s only two key bits of address book information here:- my name and my website address. Let\u2019s push it a little and say that the Web Standards Project is the organisation I work for \u2013 that gives us Name, Company and URL.\n\nTo kick off an hCard, you need a containing object with a class of vcard. The div I already have with a class of bio is perfect for this \u2013 all it needs to do is contain the rest of the contact information.\n\nThe next thing to identify is my name. hCard uses a class of fn (meaning Full Name) to identify a name. As is this case there\u2019s no element surrounding my name, we can just use a span. These changes give us:\n\n
\n

About the author

\n

Drew McLellan is a web developer...\n\nThe two remaining items are my URL and the organisation I belong to. The class names designated for those are url and org respectively. As both of those items are links in this case, I can apply the classes to those links. So here\u2019s the finished hCard.\n\n

\n

About the author

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Drew McLellan is a web developer, author and \n no-good swindler from just outside London, England. \n At the Web Standards Project \n he works on press, strategy and tools. Drew keeps a \n personal weblog covering web \n development issues and themes.

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\n\nOK, that was easy. By just applying a few easy class names to the HTML I was already publishing, I\u2019ve implemented an hCard that right now anyone with Greasemonkey can click to add to their address book, that Google and Yahoo! and whoever else can index and work out important things like which websites are associated with my name if they so choose (and boy, will they so choose), and in the future who knows what. In terms of effort, practically nil.\n\nWhere next?\n\nSo that was a trivial example, but to be honest it doesn\u2019t really get much more complex even with the most pernickety permutations. Because hCard is based on vCard (a mature and well thought-out standard), it\u2019s all tried and tested. Here\u2019s some good next steps.\n\n\n\tPlay with the hCard Creator\n\tTake a deep breath and read the spec\n\tStart implementing hCard as you go on your own projects \u2013 it takes very little time\n\n\nhCard is just one of an ever-increasing number of microformats. If this tickled your fancy, I suggest subscribing to the microformats site in your RSS reader to keep in touch with new developments.\n\nWhat\u2019s the take-away?\n\nThe take-away is this. They may sound like just more Web 2-point-HoHoHo hype, but microformats are a well thought-out, and easy to implement way of adding greater depth to the information you publish online. They have some nice benefits right away \u2013 certainly at geek-level \u2013 but in the longer term they become much more significant. We\u2019ve been at this long enough to know that the web has a long, long memory and that what you publish today will likely be around for years. But putting the extra depth of meaning into your documents now you can help guard that they\u2019ll continue to be useful in the future, and not just a bunch of flat ASCII.", "year": "2005", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2005-12-06T00:00:00+00:00", "url": "https://24ways.org/2005/practical-microformats-with-hcard/", "topic": "code"}