JavaScript

Since I've come from the land of desktop application development, there are a few concepts that I don't think quite "made the voyage" from desktop/thick-client development to web/thin-client development. The concept of "data binding" is completely lost in my opinion in the land of Javascript and HTML (not to mention the concept of "controls" to begin with).A few weeks ago while exploring a couple other concepts for how to improve our overall frontend development at Slide I prototyped a means of "databinding" controls, or at the very least DOM elements to data-providing Javascript functions.

I've posted an example here of some of the data binding code I've written for experimentation purposes. In the example page linked, there is a <ul> tag that is "bound" to a Javascript function, the Javascript function creates an array of associative arrays inline (it could very well be powered by some AJAX-oriented Javascript with minor adjustments). Using the results of the "databind" function specified on the bindable element, it creates a set of child nodes to attach to the parent list. In effect, the following code:

<script type="text/javascript">
    var bindSimpleList = function() {
        var simple_list = new Array();
        simple_list.push({'contents' : 'List Item #1 OMG', 'onclick' : function() { alert("You clicked the first list item! lulz"); }});
        simple_list.push({'contents' : 'List Item #2', 'style' : 'border-bottom: 1px dashed red; width: 100px;'});
        simple_list.push({'contents' : '<strong>List Item #3</strong>'});
        return simple_list;
    }
</script>
<ul class="bindable" databind="bindSimpleList" databindto="li"</ul>
</ul>

<ul class="bindable" databind="bindSimpleList" databindto="li">
    <li onclick="alert('You clicked the first list item! lulz');">List Item #1 OMG</li>
    <li style="border-bottom: 1px dashed red; width: 100px;">List Item #2</li>
    <li><strong>List Item #3</strong></li>
</ul>

Since the code is relatively simple (in my opinion) I figured I would throw it out there in all it's minimalistic glory and get some general feedback on the concept before I go "all out" and create a full-on jQuery extension based off of the linked prototype above. I'm trying to think of ways to make it more powerful as well, built-in support for binding to the results of an asynchrounous call to a URL that returns JSON that would then create the elements is at the top of my TODO list at this point. Feedback, flames and actual useful critiques are all welcome; I'll be sure to post again once I have the time to create the jQuery extension for binding, this however is more experimental quality (i.e. don't use it, i'm not).

What do you think?

Via twitter I have been griping a bit about Javascript recently. It's quite possible that I've been complaining about it far more than I complain about other things via twitter, which is a tall order to match.

When addressing something as big and scary as say, a platform built on Javascript, it forces you into looking at Javascript in a way different than how I think most developers (myself included) have looked at Javascript. Most Javascript that I've seen has been hideous. Gobs and gobs of functions and procedural garbage thrown into a series of files that kinda makes sense, but really doesn't. It would seem that most developers charged with writing Javascript don't understand how to write object-oriented Javascript. In fact about two or three months ago when considering topics to discuss in a front-end developers meeting here at Slide, I bit the bullet, raised my hand and said "Can you explain how to do object-oriented Javascript? Because I honestly don't have a fucking clue."

In the past Javascript that I've written has been to compliment existing backend web-application code and front-end code, i.e. I wasn't looking at Javascript as one of the building blocks of my application, I was looking at it as a bit of mortar spread between the cracks to smooth out the surface of the application. The difference in how you start to use Javascript in a web application makes an enormous difference 6 months to a year down the road. How terrible your code (this isn't actually segregated to Javascript) is becomes far more apparent when other developers start to work with your code as well, it's tremendously embarrassing to have to answer questions like "where's the code that generates that one DOM element?" As a general rule, coding all by your lonesome, especially with a tight schedule, will produce less than clean results (unfortunately Javascript is one of the languages I've found where this is more of the norm than the exception).

A lot of what's driven the change from my Javascript being the mortar to being the bricks in my work has been the adoption of jQuery which I highly recommend along with the jQuery.ui library. jQuery makes developing Javascript feel like actual programming, instead of hackish-scripting, which means you'll start to view your Javascript code differently too. Dealing with scoping issues, and prototype-based programming in Javascript isn't all rainbows and butterflies but "doing it right" will help you sleep at night and help reduce the amount of embarrassing questions you'll have to answer to the next poor unfortunate soul that inherits your code.

Some of the resources I've found useful in getting over the barrier to object-oriented Javascript have been:

• This Introduction to Object-Oriented Javascript on the Mozilla Developer Center
• Almost anything John Resig writes, especially gems like his recent post on Simple Javascript Inheritance
• The code included in some mainstream javascript libraries

I'm still not a huge fan of Javascript, but I'm hating it less these days :)

I've been doing work with OpenSocial recently and have used the opportunity to bring my tolerance talent in Javascript up a notch or two. In doing so, I've been slowly but surely running into a myriad of browser-specific quirks along with a few cross-browser gems that have left me thinking about putting some browser developers on my "To Anonymously Beat Up In Alleyway" list (so far, James Gosling, and this man top the list).

After working on a few "classes" tonight (the notion that Javascript is object-oriented still makes me chuckle) I ran into an interesting problem with some of my global-level "constants" defined in the same file that I was working in, that my "class" just so happened to make use of. As I tend to do when I fall into situations like this to where I can't tell if I'm hallucinating or if something with Javascript has gone awry, I called over Sergio (in-house CSS master and Javascript Lvl. 60 Mage).

Some background to how Javascript works
Javascript engines essentially have two "modes" that it runs over your code that you can spot errors in. The first mode, "parsing", is where you'll find syntax errors spewing into the Javascript console. If you've used any interpreted language before (Python, Java, C#, Ruby), this is really just "compilation". Using Python as an example, when you import a module (i.e. import some_module) the Python interpreter actually compiles your code into Python byte-code to be executed at a later date. The second mode, "execution", is where you'll run into your run-time errors, using an accessing an undefined object property, overrunning an array index, etc. In Python/Java terms, this is where your compiled byte-code is actually being run in the Python/Java virtual machine.

The gripe
The crux of the problem comes down to two different ways to declare an associative array in Javascript, the following two notations are both correct and both "work":
Notation #1

var mapped_values = {};
mapped_values['key'] = 'value';

var mapped_values = {'key' : 'value'};