November 19th, 2009 §
Any JavaScript developer who spends more than a blink of an eye working with the DOM has probably come despise the API. It’s not that there’s a dearth of features (welll….); I think it’s the verbosity that causes modern application development woes. For the one-off script that adds an onclick or modifies some text the DOM API is fine and dandy. Try scaling up to developing an application or, perhaps, a framework and things get annoying and messy right quick.
When Tommy finally gave jQuery a try and discovered there was no native DOM manipulation tools he decided to roll his own plug-in he calls FluentDom. The code is clean and quality, as I’d expect from him, but the interface drives me bonkers.
I’m a fan of configuration over convention, a concept which, when combined with my MooTools history, has lead me to favor using object literals as configuration “objects”. When I use MooTools to create a new element the only arguments are the element type and an object literal with any configuration options. This is where Tommy’s code style differs. In FluentDom you set a specific attribute with specific methods with calls able to be chained together. This isn’t to say that FluentDom couldn’t be used with a configuration object, it’s just not as clean an implementation as I prefer.
In a message to him I said this:
The benefit to setting attributes via an object literal is that I can use one set of preset attribute values and pass that around. Quite handy if you’re doing something like iterating and creating a list of similar elements but particular ones might have subtle differences. Also easier to maintain and extend. Given your code it’d be a trivial modification to do this during a create call.
Which do readers prefer, specific, chainable method calls or ambiguous configuration object?
October 29th, 2009 §
Or: There are legit reasons to write your own library
Around the office it’s no secret that I’m a fan of the MooTools JavaScript library. For those of you who can remember back before jQuery, Moo.fx (from whence MooTools came) was a tiny, feature rich library for animations and effects. It was a welcome relief from having to write effects and deal with the cross-browser issues that invariably crop up. Compared to the heavy weight (and necessity) of including both the Scriptaculous and Prototype libraries, Moo.fx was a boon for byte-pinching developers and infrastructure managers.
Over the years as many libraries popped up and fell by the wayside, jQuery came along and showed us the difference between a library and a framework. Perhaps the most important result of competition between libraries was performance. I won’t hold MooTools above any other library arbitrarily but when they created SlickSpeed it was a great way to show performance between libraries and let developers decide what library best fit needs. John Resig came along and blasted out Sizzle and – BAM – kicked up the speed of jQuery by a wide margin. The healthy competition rages on and it just means better speed, compatibility and features for users of JavaScript libraries.
With the availability of tested, proven, mature libraries why would anybody ever bother writing their own native JavaScript code any more? I know that the last time I write document.getElementById() can’t come soon enough. Still, there are reasons to stick to pure, native JavaScript.
For starters, no matter how elegant or optimal the code a library’s code will never be as efficient as native JavaScript. Sure, they may delegate to native functions and the cost could end up being a millisecond or two. That’s fine. Then again, do you want to be the one tracing back performance issues when your code causes a locked browser when you run var header = $('header'); and hit some kind of weird edge case?
I had a better reason than performance. I’m a realist. I don’t have the time or patience to write the fastest code in the west. I write code to solve solutions. Functionality first, optimization second. That doesn’t mean that I write slow or hacky code. I just want to get the problem solved first and sometimes it’s easier to write something in straight JavaScript instead of finding a MooTools class or a jQuery plugin, making sure it doesn’t pollute the namespace, assuring that it runs reliably and trying to configure it for my specific needs, even though it was never meant for that.
Sadly, it has been a few years since I’ve been able to really stretch my JavaScript legs and run. From a CTO who banned the use – and all but the mention of – AJAX to projects that were more business rules than user interface I haven’t had just cause to go nuts on the client side. There have been occasional forays into widgets and code snippets but nothing serious. Any real geek should realize that a dearth of reasons to code passionately causes bad things to happen in a programmer’s brain.
The straw that broke the camel’s back was a manager walking over to me, asking me if JavaScript could do XYZ, to which I boldly assured him it could. I sat down, cracked open a fresh TextMate skeleton project and stared blankly at the screen. I had no idea how to accomplish the task, where to look for guidance or even if I could get it done. This could not stand. I needed a core JavaScript refresher. More than that, I needed to cover topics I had never mastered like, say, wholly p0wning the DOM.
It was at that moment that I decided to write my own JavaScript library. Not to have more features. Not to be the fastest. Not to be the most popular. Simply to better understand the language and environment in which it is most often run. A refresher on what I know, a chance to learn new tricks and an opportunity to better learn how to architect something bigger than a snippet.
Things are progressing nicely and when there is a stable base and interface I plan on releasing the code open and free. I doubt it will blow the minds of any seasoned JavaScript experts but already I have some tricks that I haven’t yet found in either MootTools or jQuery. It has been frustrating, fun and frivolous – all the best attributes of any personal code project.
I’ll be clear: I do not recommend writing your own library, framework or other massive code base. Not on a whim, at least. It’s not worth the time to do something that is only half as good as what already exists.
However, you cannot call yourself an expert at anything without knowing how the guts work. Knowing how fuel injection works does not make me a champion race car driver.
And that’s how I’ll end this chapter. JavaScript programmers are not race car drivers.
June 16th, 2009 §
If you don’t already know, polluting the global variable pool is a bad, evil thing in JavaScript land. If you’re not concerned with overwriting existing code then at least think about protecting your code from being overwritten by keeping it in your own namespace. All you need to create a namespace in JavaScript is an object literal.
Say you’re tasked with incorporating a third-party widget into your home page. You drop in their
function findElement(el) {
return document.getElementById(el);
}
function updateNews(content) {
findElement('news').innerHTML=content;
}
That is some horrible code. Worse, that’s horrible code in the global pool. Cracking open the third-party include you see this:
updateNews = function(container,source,freq)
{
// Snip....
}
My, that function name looks awfully familiar. In fact, it’s the same as yours. That means your code and the third-party code are fighting in the global variable pool. What’s a clever programmer to do? Do what works in other languages, of course!
Time to carve out your own namespace
This is ridiculously easy if you understand what object literals are and how to self-invoke an anonymous function. Those terms both sound scarier than they are. You simply create an object literal to act as your namespace – which is a bucket for all your code – then use anonymous functions to assign functions into it. Keeping with the theme of being a polite player in the global pool also make sure your namespace is either brand new or extends any existing namespace.
var AY = AY || {}; //Don't overwrite existing namespaces
AY.News = function() //A 'News' bucket for all news-related tasks
{
//The 'var' forces the findElement method
//into the News scope, not global
var findElement = function(el)
{
return document.getElementById(el);
}
//Anything in the return becomes publicly accessible, yet
//is also able to access private methods and variables
return {
updateNews: function(content)
{
findElement('news').innerHTML = content;
}
}
}(); //Self-invoke to make this available immediately
AY.News.updateNews('Hai');
What’s happening here? Well instead of dropping all of your code into the global you can stash it in a single namespace. In my case I’ve named my namespace as AY, after my name. I used all capital letters to signify that this is not a variable or method belonging to any other code. For news-related items I’ve created a News bucket.
Inside of my News bucket there are a few things happening. I’ve decided that findElement should be a private method in my namespace so by prepending it with the var = I designate it as existing only inside the AY.News namespace. Without a public accessor no outside code can run that method. My return passes an object literal which houses any public methods, in this case the updateNews method. Because they are a part of my AY.News namespace these public methods can access private methods, which is why the updateNews code still works.
Finally, the closing parentheses cause the anonymous function to automatically run, or self-invoke. This action executes the function and, during its execution, hits the return which is what causes the return data to be assigned to AY.News. The return is an object literal itself that contains a reference to the “private” updateNews, which will execute the update.
That’s it! There’s no more to it. I’ll grant that for personal scripts this technique is not absolutely necessary but if you ever want your code to play nicely in another environment it’s a good practice and makes other programmers less hesitant to use your code. Comments regarding execution of this technique are more than welcome. This is my personal flavor and because of JavaScript’s flexibility I’m sure there are some other great techniques out there. Comment away!
Recommended reading:
2009-06-17: Reordered and cleaned up copy.