Rey Bango

Here’s a question. Given 3 days and allotted 1 day per developer, which 3 developers would you spend it with? Here’s the caveat, the developers MUST BE in the web development community.

Here are my choices in no specific order:

• Nicole Sullivan – Why? Because she is a freaking CSS guru and the amount of CSS knowledge I could gain from a day of her mentoring would be so incredibly valuable. She’s also a super-cool person.
• Nicholas Zakas – Why? Well, there are a lot of people who are really awesome JavaScript developers but few, in my opinion, who have the experience in a large-scale environment. Nicholas has that, as the principal front-end engineer for Yahoo! and that’s knowledge worth nabbing. And if you’ve watched his presentations, you know he can teach.
• Joe Stump – Why? Because Joe is one of the coolest dudes on the planet and apart from that, he has the knowledge to build out BIG sites. Now that he’s focused on geolocation, getting into that would be so cool. Plus, I know Joe loves kids so I could talk to him about babies and stuff.

Now, my list isn’t meant to leave anyone out because there are a ton of people who I’d like to learn from. This is just a group who I feel, at the moment, would offer knowledge that I want right now and they’re just great for providing that. So hopefully, I won’t hurt anyone’s feelings.

So who would you pick?

Binding events is one of the most common tasks a JavaScript developer has to do. It’s integral to the way our applications handle user interaction and response. Since it’s inception, jQuery has had event handling via various helper methods that helped to abstract cross-browser differences. If you’re a jQuery developer, I’m sure you’re used to syntax like this:

$("#clname").click( function() { alert( "Rey" ) } );

which would bind a click event to a DOM element with an ID of “clname”. Very easy to understanding and simple to use. But when you get past just simple use of JavaScript and start inserting new DOM nodes, this binding becomes less useful because it can’t handle dynamically inserted elements. Let me explain.

Say you have the following HTML markup:

<div id="clcontainer">
<a href="#" class="clients">Click for Rey Information</a>
</div>

and you bind the click event to generate an alert of some type like this:

$(".clients").click( function() { alert( "Here's some information." ) } );

but then you decide that you’re going to add a new DOM element to the page dynamically:

$("#clcontainer" ).append( "<a href='#' class='clients'>Click for Mark Information</a>" )

What do you think will happen? I would venture many developers might expect that the second, dynamically appended DOM element would share the same binding as the first since they share the same class name. That’s not the case. jQuery methods such as click(), dbclick(), and bind() are meant to bind events to a specific set of available DOM elements (i.e: not dynamically appended). (Note: I updated this part to better clarify what I meant based on feedback by Jamie Newman)

Now to get around this limitation, jQuery team member Brandon Aaron initially created a plugin called LiveQuery which would allow you to bind events not only to specific DOM elements but all subsequent DOM elements that were appended to the DOM that matched the selector specified in the initial binding. That plugin eventually became part of the jQuery Core library and renamed simply to live(). The great thing with live() is that you could now bind dynamically added DOM elements like this:

$(".clients").live( "click", function() { alert( "Here's some information." ) } );

and if you did append a new DOM element, like this:

$("#clcontainer" ).append( "<a href='#' class='clients'>Click for Mark Information</a>" )

it would now share the same function binding as initially defined.

The Problem with Live()

Now, live() is an awesome method and people totally loved it. That is, until they wanted to bind events based on a deeper DOM traversal than just a single element, specifically when methods were used that alter the selector expression’s initial results (e.g.: using children()). So, if we had markup like this:

<div id="clcontainer">
	<ul>
		<li>Mary</li>
		<li>Jane</li>
	</ul>
</div>

and tried to use live() to bind all of the list items like this:

$("#clcontainer").children( "ul" ).find( "li" ).live( "click", function() { alert( "Here's some information." ) } );

the binding would fail. Since chaining is so widely used within the jQuery community, this was a bit of a surprise to many and one of the most requested updates to jQuery.

In order to get around this, Brandon introduced in jQuery v 1.4 the new delegate() method. It provides greater control by allowing you to specify the context to which you’d like to bind to. So using the same example as above and making some slight changes to use delegate(), we’re now able to use chaining to determine our selector results and then specify that we’d like all current and future list items to be bound to our declared function:

$("#clcontainer").children( "ul" ).delegate( "li", "click", function() { alert( "Here's some information." ) } );

When to Use live() or delegate()

These two convenience methods are totally awesome and incredibly helpful with more complex apps. The best use case for them is when you know that you will be dynamically adding new DOM elements and they’ll share the same bound function. I mean, essentially that’s the premise of event delegation. You’re trying to limit the number of event handlers needed to handle functionality and increase maintainability be centralizing your logic. Make sense. If you’re not going to be doing anything that involved, though, then jQuery’s event helper methods such as bind(), click() etc. are still excellent choices for those one-off scenarios.

My biggest focus at Microsoft is the Script Junkie website. We use it to publish really great cross-browser, solutions-based content to help developers improve their JavaScript, HTML, & CSS development efforts.

The Script Junkie team is working on our content plan for the next six months and we’re looking to identify developer problem areas that we can provide solutions for. So I’m reaching out to my blog readers in an effort to understand what type of things pain you. Here are some examples of problem areas that we’ve heard of:

• Designing and implementing for multiple devices like 42″ LCD TVs to 480px Android device
• Getting users to upgrade their browsers in a friendly way
• Developing cross-browser compatible websites with minimal hacks
• How realistic is it to begin using HTML5 & CSS3 today?

It’s important to note that that we’re not looking for answers to the above problem areas at this time. These are examples to demonstrate the type of concerns we’re hearing. We’re looking for more questions that hopefully we can answer via solutions-based articles and code. So if you have thoughts on wide-spread development problems that you’d like to see tackled, please comment below. Remember that Script Junkie focuses on JavaScript, HTML and CSS so please be sure to keep that in mind when listing out your pain points.

We’ll roll-up your comments and then focus on the top 10 things listed by the development community.

Thanks for your help!

Over the years, I’ve read or been recommended a number of books which are essential reading for professional web developers. I’ve compiled the list of books below to help the community find a comprehensive list of good books that can help them be better coders.

JavaScript

Professional JavaScript for Web Developers – My new favorite book. Almost 1,000 pages of VERY detailed JavaScript information. Written by Nicholas Zakas, Yahoo! Principal Front-end Engineer for Yahoo!’s home page and recommended by the YUI team as well. BUY THIS BOOK!

JavaScript: The Definitive Guide – Considered the Bible of JavaScript for its thorough coverage of JavaScript. You need to have this in your library, even as a reference.

DOM Scripting: Web Design with JavaScript and the Document Object Model – This is a good book to get you familiar with the DOM.

AdvancED DOM Scripting: Dynamic Web Design Techniques

Beginning JavaScript with DOM Scripting and Ajax: From Novice to Professional – The book by Christian Heilmann that really got me past the initial hump of plain ‘ole JavaScript. His writing style is awesome.

Object-Oriented JavaScript: Create scalable, reusable high-quality JavaScript applications and libraries – JUST BUY THIS BOOK! Stoyan did a great job of outlining OOJS principles and it’s been incredibly valuable.

JavaScript: The Good Parts – It’s certainly a good book and I would recommend reading it after one of the more intro books like JS for Web Developer by Nicholas Zakas.

Learning jQuery 1.3 – While covering jQuery v1.3, the techniques discussed are still useful and I still recommend the book highly.

Pro JavaScript Techniques – John Resig’s famous book on advanced JS techniques.

Secrets of the JavaScript Ninja – Still not out but considering that John Resig is that author, it’s sure to be great.

ppk on JavaScript, 1/e – One of the first books I picked up and great overview of the language.

Accelerated DOM Scripting with Ajax, APIs, and Libraries

Ajax Security – Billy Hoffman is the man when it comes to Ajax security and this books shows why.

jQuery Cookbook: Solutions & Examples for jQuery Developers (Animal Guide) – Tips & techniques from the jQuery team rolled up in a cookbook style. You can’t go wrong.

jQuery in Action, Second Edition – This is now updated for jQuery v1.4.x as well as jQuery UI 1.8.x. Definitely a must-have for jQuery developers

jQuery Enlightenment – Cody Lindley did an amazing job in outlining the best jQuery techniques in this self-published book. Totally worth the price.

Test-Driven JavaScript Development

jQuery: Novice to Ninja

HTML & CSS

Web Standards Solutions: The Markup and Style Handbook, Special Edition

Bulletproof Web Design: Improving flexibility and protecting against worst-case scenarios with XHTML and CSS (2nd Edition)

The Art & Science Of CSS – This is one of Sitepoint’s best CSS books. Loved it.

HTML Utopia: Designing Without Tables Using CSS, 2nd Edition – Not being a designer, I thought this book was a tremendous help in understanding how to better design sites.

Head First HTML with CSS & XHTML – This has been my goto book for some time. The Head First books are just so great at breaking down topics in easy to understand ways and this book is no exception.

Introducing HTML5 (Voices That Matter) – Going to get this soon mainly because it’s written by Remy Sharp and Bruce Lawson whom I respect tremendously, especially for their HTML5 & CSS3 savvy.

HTML5 For Web Designers – Just got this on 7/19/10. Need to read it by it’s by Jeremy Keith and he rocks.

CSS Cookbook, 3rd Edition (Animal Guide) – Just picked this up on a recommendation.

CSS: The Missing Manual – I keep hearing rave reviews about this book all over the place.

Site Performance & Enhancement

High Performance Web Sites: Essential Knowledge for Front-End Engineers – Steve Souders is the performance guru and if you want your apps to perform better, get this book and the one right below this one.

Even Faster Web Sites: Performance Best Practices for Web Developers

High Performance JavaScript (Build Faster Web Application Interfaces) – Again, another great book by Nicholas Zakas which outlines very important performance techniques for JavaScript applications.

Designing with Progressive Enhancement: Building the Web that Works for Everyone – Great book on progressive enhancement by the superstars at the Filament Group.

This is certainly not all inclusive and I’m sure there are other books out there that have been great. If you feel very passionate about a specific title, let me know via the comments and I’ll check it out.

So far in my series on jQuery JavaScript Templating, I’ve showed how to create a basic jQuery JavaScript template and then nest templates for increased layout flexibility and maintainability. If you haven’t read those two posts, I highly recommend you do so you can understand the concepts below.

Now, let’s dive into two other techniques available in the Microsoft jQuery Templates plugin; inline expressions and code blocks.

Inline Expressions

Being able to use a template to create a succinct layout is very powerful but without the ability to manipulate the data that’s being rendered, you’d probably find templates a lot less useful. That’s where inline expressions come in. Inline expressions allow you to use common JavaScript expressions to effect a change in the way your data is rendered. Using a slightly modified version of the data from my last tutorial, I can show you what I mean. Here’s the data:

var clientData = [
     { first: "Rey", last: "Bango", age: 42, id: 1, phone: [ "954-600-1234", "954-355-5555" ] },
     { first: "Mark", last: "Goldberg", age: 51, id: 2, phone: ["954-600-1234", "954-355-5555"] },
     { first: "Jen", last: "Statford", age: "25", id: 3, phone: ["954-600-1234", "954-355-5555"] }
 ];

What I did was break out the “name” attribute into “first” and “last” name fields. Now, say I wanted to render the full name in my template. I would use the following inline expression to do so:

<script id="clientTemplate" type="text/html">
    <p><li>${ first + " " + last }</li></p>
</script>

Which gives me the following result:

Notice that I’m using the standard JavaScript “+” operator to concatenate the two data attributes together to form my final output. JavaScript developers should immediately be able to understand the code here and see how flexible this option is.

Code Blocks

Now, while inline expressions are certainly powerful, the ability to affect the data via code blocks is even more important because it allows you to specify conditional statements that can be used to determine what type of and when data will be represented. Let’s say that based on the age of a client, I want to show some text next to their name. I’ll use the following code block:

{{if (age > 30)}}veteran coder!{{else}}rising star!{{/if}}

This code block allows me to specify a conditional statement that allows me to create a nice descriptor based on the person’s age. The key is the “{{if..else}}” custom tag that’s been incorporated into the template plugin that allows you to specify conditional statements.

Here’s what the template would look like:

<script id="clientTemplate" type="text/html">
    <p><li>${ first + " " + last + " is a " }{{if (age > 30)}}veteran coder!{{else}}rising star!{{/if}}</li> </p>
</script>

which generates the following results:

And again, the cool thing is that the syntax for the expressions use standard JavaScript operators so I can do something like this as well:

{{if (age > 20 && age < 30 || age == 42)}}rising star!{{else}}veteran coder!{{/if}}

The thing to stress here is that using inline expressions and code blocks together can give you a tremendous amount of control over how you control you data. You have the flexibility you’d expect by using JavaScript but in a manner that is easily readable and maintainable.

Here’s the final code:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <meta name="robots" content="noindex" />
  <title>Template Test</title>
  <script src="http://code.jquery.com/jquery.min.js" type="text/javascript"></script>
  <script src="jquery.tmpl.js" type="text/javascript"></script>
  <script type="text/javascript">
  $(document).ready(function() {

var clientData = [
     { first: "Rey", last: "Bango", age: 42, id: 1, phone: [ "954-600-1234", "954-355-5555" ] },
     { first: "Mark", last: "Goldberg", age: 51, id: 2, phone: ["954-600-1234", "954-355-5555"] },
     { first: "Jen", last: "Statford", age: "25", id: 3, phone: ["954-600-1234", "954-355-5555"] }
 ];

        $("#clientTemplate").tmpl(clientData).appendTo("div");

});
  </script>

<script id="clientTemplate" type="text/html">
    <p><li>${ first + " " + last + " is a " }{{if (age > 20 && age < 30 || age == 42)}}rising star!{{else}}veteran coder!{{/if}}</li> </p>
</script>

</head>

<body>

<div></div>

</body>
</html>

I just finished my presentation at Think Vitamin’s jQuery Online Conference and it was such a great experience. This is the first BIG virtual conference I’ve presented at and it ran smooth as silk. I really have to hand it to the Carsonified team; they have their act together.

The big takeaways:

• Online conferences rock! No travel == less expenses.
• The technology is good enough to be able to do this and WebEx is awesome.
• Carsonified’s got this down. While some tech problems are expected, they’ve really got the process working well.

The only downside, from a speaker perspective, is that you really can’t see how your audience is reacting. That’s tough because sometimes, you’re able to adjust according to your audience’s feedback. If there’s dead silence, you know you need to bring them back. If they’re engaged, you know you’re on track. In a virtual conference, you can’t gauge that so it’s tough.

Lots of folks have asked for the code for the Twitter demo that I did. You can now download that below:

Download the Twitter Demo Source

I want to thank everyone for attending and for the kind words. I really appreciate it. I also want to thank Carsonified for giving me the opportunity to speak at a great event.

In my last post, I presented an intro to how to create a template using the new jQuery Template plugin being developed by the Microsoft Ajax Core team. In this tutorial, I’ll show you how to nest templates to have great control over your layout.

The nesting of a template within another template is a pretty valuable feature as it lets you create a modular structure for your layout. Instead of having to create one enormous template to cover every scenario, you can break the layout apart into individual templates and piece them together. Let’s start by defining some data:

       var clientData = [
	        { name: "Rey Bango", age: 42, id: 1, phone: [ "954-600-1234", "954-355-5555" ] },
	        { name: "Mark Goldberg", age: 51, id: 2, phone: ["954-600-1234", "954-355-5555"] },
	        { name: "Jen Statford", age: "25", id: 3, phone: ["954-600-1234", "954-355-5555"] }
        ];

What I’d like to do is to render the basic information like the name and age in one template and then render the phone numbers for each client in a different template.

Like I showed in my previous post, we first create a template for our layout:

<script id="clientTemplate" type="text/html">
	<p><a href="clients/${id}">${name} - Age: ${age}</a></p>
</script>

This will display the name and age as a hyperlink included within paragraph tags. Next, we create a new template that will be used to render the phone numbers for each client”

<script id="phoneTemplate" type="text/html">
	<ul>{{each phone}}<li>${$value}</li>{{/each}}</ul>
</script>

Lastly, we’re going to include the call to “phoneTemplate” in our main template using the “tmpl” tag. This tag is used by the plugin to identify templates and parse them accordingly. Here’s what the call would look like:

{{tmpl($data) "#phoneTemplate"}}

and we’re going to include it into the main template:

<script id="clientTemplate" type="text/html">
	<p><a href="clients/${id}">${name} - Age: ${age}</a></p>
	{{tmpl($data) "#phoneTemplate"}}
</script>

This will generate the following results:

There are a couple of key things to understand here. First, let’s look at the following:

{{tmpl($data) "#phoneTemplate"}}

The variable “$data” contains the data for the current record being parsed. We’re passing it to the nested template so that we can work with that record. Let’s move onto the nested template:

<script id="phoneTemplate" type="text/html">
	<ul>{{each phone}}<li>${$value}</li>{{/each}}</ul>
</script>

Now that the current record has been passed to it, we can access the attribute name, in this case “phone”, and loop through each phone record using the ‘{{each}}‘ plugin template tag. Think of it as similar to jQuery’s $.each() method or a JavaScript “for” loop. The code will loop through each phone record creating a new list item for each one and then return to the main template to get the next main record.

Here’s the whole code for you to work with:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <meta name="robots" content="noindex" />
  <title>Template Test</title>
  <script src="http://code.jquery.com/jquery.min.js" type="text/javascript"></script>
  <script src="jquery.tmpl.js" type="text/javascript"></script>
  <script type="text/javascript">
  $(document).ready(function() {

        var clientData = [
	        { name: "Rey Bango", age: 42, id: 1, phone: [ "954-600-1234", "954-355-5555" ] },
	        { name: "Mark Goldberg", age: 51, id: 2, phone: ["617-777-1234", "617-222-3333"] },
	        { name: "Jen Statford", age: "25", id: 3, phone: ["608-555-5647", "608-645-8855"] }
        ];

        $("#clientTemplate").tmpl(clientData).appendTo("div");

});
  </script>

<script id="clientTemplate" type="text/html">
	<p><a href="clients/${id}">${name} - Age: ${age}</a></p>
	{{tmpl($data) "#phoneTemplate"}}
</script>

<script id="phoneTemplate" type="text/html">
	<ul>{{each phone}}<li>${$value}</li>{{/each}}</ul>
</script>

</head> 

<body> 

<div></div>

</body>
</html>

In preparation for my upcoming talk on jQuery Templates, I’ve been been deep diving into the jQuery Template plugin created by Microsoft.. Many of you are probably familiar with server-side template engines like Smarty or Cheetah but only recently have client-side template engines taken off. Considering how complex our web apps are becoming, it makes total sense.

The cool thing about templates is that it lets you easily structure your content display without all the hassle of string concatenation. For example, say I had a data set containing an ID and a name and I wanted to display the name as a hyperlink.

I could do something like this:

var clRec = "";

for(var i=0; i<client.name.length; i++) {
    clRec += "<li><a href='clients/"+client.id[i]+"'>" + client.name[i] + "</a></li>";
}

but to me, this seems much more readable and maintainable:

<li><a href="clients/${id}">${name}</a></li>

The second code snippet is a template I’ve created to render a hyperlinked name in a list and it’s very easy to do. First, include both jQuery and the jQuery Template plugin into your page:

<script src="http://code.jquery.com/jquery.min.js" type="text/javascript"></script>
<script src="jquery.tmpl.js" type="text/javascript"></script>

Next, define the data that you’d like to see rendered. This could be data derived from an XHR call or something you’ve predefined, like this:

	var clientData = [
		{ name: "Rey Bango", id: 1 },
		{ name: "Mark Goldberg", id: 2 },
		{ name: "Jen Statford", id: 3 }
	];

Now, define your template:

<script id="clientTemplate" type="text/html">
	<li><a href="clients/${id}">${name}</a></li>
</script>

Yep, the “script” tags are necessary and used because they allow your template to be embedded within the body of the page. Notice that we’ve defined the placeholders as ${id} & ${name}, the same names used in the identifiers in our data. The “${}” tells the template parser that the field needs to be replaced with the expected value.

Then call the jQuery Template plugin to render the data using your template:

$("#clientTemplate").tmpl(clientData).appendTo( "ul" );

The plugin’s .tmpl() method accepts the data we’ve defined and handles the parsing of the template we’ve selected. Then we use jQuery’s .appendTo() method to append the results to an unordered list tag. This gives me the following results:

That’s it! Told you it was simple.

I’ll go into more advanced details during my presentation but this should give you something to start with in the meantime. Here’s the full source for you to use:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <meta name="robots" content="noindex" />
  <title>Template Test</title>
  <script src="http://code.jquery.com/jquery.min.js" type="text/javascript"></script>
  <script src="jquery.tmpl.js" type="text/javascript"></script>
  <script type="text/javascript">
  $(document).ready(function() {

	var clientData = [
		{ name: "Rey Bango", id: 1 },
		{ name: "Mark Goldberg", id: 2 },
		{ name: "Jen Statford", id: 3 }
	];

$("#clientTemplate").tmpl(clientData).appendTo( "ul" );

});
  </script>

 <script id="clientTemplate" type="text/html">
	<li><a href="clients/${id}">${name}</a></li>
</script>

</head> 

<body> 

<ul></ul>

</body>
</html>

This coming Monday (7/12/2010), I’ll be one of the speakers at Think Vitamin’s jQuery Online Conference. I’ll be speaking about using the Microsoft jQuery Template plugin to produce easily maintainable dynamic pages via pre-built JavaScript templates. This is a great topic and it looks like the event is generating a lot of registrations. Very cool.

I’ll be joined by three other awesome speakers including John Resig, Karl Swedberg and Ben Alman. Here’s the breakdown of the sessions:

Topics and schedule

• Beyond String Concatenation. Using jQuery Templating to Cleanly Display Your Data
  Rey Bango
  In this presentation, Rey will show you a new way to produce easily maintainable dynamic pages via pre-built JavaScript templates and the Microsoft jQuery templating plugin.
• Testing Your Mobile Web Apps
  John Resig
  This talk will be a comprehensive look at what you need to know to properly test your web applications on mobile devices, based upon the work that’s been done by the jQuery team. We’ll look at the different mobile phones that exist, what browsers they run, and what you can do to support them. Additionally we’ll examine some of the testing tools that can be used to make the whole process much easier.
• Taking jQuery Effects to the Next Level
  Karl Swedberg
  One of the first things web developers learn to do with jQuery is to show and hide elements on a page and then add some flair by sliding those elements up and down or fading them in and out. Too often, though, we stop there, missing out on the incredible range and flexibility of jQuery’s core effects. In this talk, we’ll investigate both standard and custom animations and how they can be used to create useful and fun effects. We’ll also build a couple effects plugins, explore parts of the effects API that are often overlooked, and learn how to avoid common problems when attaching these effects to certain events.
• jQuery Pluginization
  Ben Alman
  In this live-coding session, Ben explains how, with just a little thought and effort around generalization, parameterization and organization, you can convert your “just get the job done” jQuery code into a legitimate, reusable, modular jQuery plugin.

This really is a great lineup and I’m looking forward to being a part of this great event. It’s been a very long time since I’ve done a presentation so this will be a good warm up for some other conferences I plan on speaking at later this year.

Be sure to use the following discount code for a 15% discount on registration: jquery15

Over the weekend I was fiddling was some code to see how to make a generic activity indicator for Ajax requests. I’m sure most of you have seen these but if not, here’s one similar to what Facebook uses:

While it’s may not look like much, that animated .gif is pretty important because it tells a user that something is happening and that results will appear shortly. The last thing you want is for a user to think the page has locked up or broken and using this simple method advises them that their request is being processed.

Targeted Indicators

In my case, I was looking for a way to set an indicator within the specific DOM element that would be affected by the XHR call. So if my XHR call was to set the contents of a specific DIV, I wanted the indicator to render within that specific DIV only (similar to what Facebook does).

First, I created three DIVs and 3 anchor tags:

<a href="#">Box 1</a>|<a href="#">Box 2</a>|<a href="#">Box 3</a> 

<br /><br />

<div id="box1">&nbsp;</div>
<div id="box2">&nbsp;</div>
<div id="box3">&nbsp;</div>

and I set the DIVs to a specific width and floated them left:

#box1, #box2, #box3 { background-color:#E5EECC; border:1px solid #D4D4D4; width: 200px; float:left; };

Next, I created a new method called fillBox() that would take the target element’s ID and use that to dynamically create a new IMG tag and insert the activity indicator. What I decided to do was leverage jQuery’s global Ajax events to create the generic handlers for this. Using ajaxStart(), which fires off when an Ajax request is initiated, I dynamically create the tag for my activity indicator and inset it using the prepend() method:

		$(ele).ajaxStart( function() {

			$(this).prepend( "<img id='throbber' src='facebook.gif' />" );

		})

Then using the Ajax global event handler ajaxStop(), I would easily delete the indicator once the Ajax request was done by using the remove() method to delete the IMG tag from the DOM:

ajaxStop( function() {

	$("#throbber").remove();

});

Lastly, using some event delegation, I created an event handler for the clicks on the anchor tags:

$( "a" ).click( function(e) {

	var el = '';
	switch(e.target.text) {
		case "Box 1":
			el = '#box1';
			break;
		case "Box 2":
			el = '#box2';
			break;
		case "Box 3":
			el = '#box3';
			break;
	} 

	fillBox( el );

});

The handler simply looked for the anchor tag’s text and based on that filled a local var with the ID that would be targeted for the indicator. It then passed that ID to the fillBox() method.

A Little Roadblock

I thought I was done and the code look pretty straightforward. When I ran this, though, I experienced some odd behavior:

When I would click on the “Box 1″ link, the indicator would correctly appear in the first DIV followed by the data populating the box. When I would next click on the “Box 3″ link, though, both the first box AND the third box would have the indicators displayed! Not good.

I looked into it and got feedback from Adam Sontag who provided the answer I needed. I had incorrectly assumed that ajaxStop() would unbind the jQuery global Ajax events from the attached element. Unfortunately it doesn’t so by using the unbind() method, I was able to resolve the issue.

		$.ajax({
		  url: 'test.php',
		  cache: false,
		  success: function(data) {

			$(ele).html( data ).unbind( 'ajaxStart' ).unbind( 'ajaxStop' );

		  }
		});

	};

The Solution Gets Easier

Then I got more feedback from Karl Swedberg which really streamlined the whole thing. He recommended forgoing the Ajax global events altogether and simply inserting the indicator via my fillBox() method directly and since I was replacing the contents of the DIVs with the html() method, there was no need to use remove() since the IMG tag was already being removed.

var fillBox = function( ele ) {

	$(ele).prepend( "<img id='throbber' src='facebook.gif' />" );

	$.ajax({
		url: 'test.php',
		cache: false,
		success: function(data) {

			$(ele).html( data );

		}
	});

};

So while I initially was looking to use jQuery’s built-in global Ajax event handlers for making this generic, I’m finding Karl’s solution much cleaner. It requires less event handlers and method calls to do the same task. Love it!

Here’s the end result and you can see the demo here:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <meta name="robots" content="noindex" />
  <title>Throbber Test</title>
  <style>
	#box1, #box2, #box3 { background-color:#E5EECC; border:1px solid #D4D4D4; width: 200px; float:left; };
  </style>
  <script src="http://code.jquery.com/jquery.min.js" type="text/javascript"></script>
  <script type="text/javascript">

	fillBox = function( ele ) {

		$(ele).prepend( "<img id='throbber' src='facebook.gif' />" );

		$.ajax({
			url: 'test.php',
			cache: false,
			success: function(data) {

				$(ele).html( data );

			}
		});

	};

	$(document).ready( function() {

		$( "a" ).click( function(e) {

			var el = '';
			switch(e.target.text) {
				case "Box 1":
					el = '#box1';
					break;
				case "Box 2":
					el = '#box2';
					break;
				case "Box 3":
					el = '#box3';
					break;
			} 

			fillBox( el );

		});

	});
  </script>

</head> 

<body> 

<a href="#">Box 1</a>|<a href="#">Box 2</a>|<a href="#">Box 3</a> 

<br /><br />

<div id="box1">&nbsp;</div>
<div id="box2">&nbsp;</div>
<div id="box3">&nbsp;</div>

</body>
</html>