Animation

As I said animating some vector properties is as simple as:

var paper = Raphael('canvas', 1024, 500);
var c = paper.circle(50, 50, 6).attr({fill : '#f00'});
c.animate({r : 10, fill : '#00f'}, 1000);

Here we change the radius and the background color of the circle for 1000 milliseconds.

The same thing can be done with any property with any other JavaScript library as jQuery. But as in jQuery, Raphael or whatever library the animation is not looping. That’s natural you can just change a property by animating it, but the looping animation suggests at least two animations. So it’s a developers job to implement this. Here’s a simple way to do this.

Two Way Animation

The solution here is using two functions calling each other.

var paper = Raphael('canvas', 1024, 500);
var c = paper.circle(50, 50, 6).attr({fill : '#f00'});

function a() {
    c.animate({r : 10, fill : '#00f'}, 1000, b);
}
function b() {
    c.animate({r : 6, fill : '#f00'}, 1000, a);
}
a();

It’s kind of strange to speak about JavaScript libraries and market share, so lets called it “popularity”. Have you ever been interested on which is the most famous JS library.

I’d guess everybody has the answer in his head, right? jQuery is becoming for the JS community something like Google for the web or IE6 on the browser’s market in the beginning of the century. How odd?!

However here’s a short list of who’s first.

1. Robert Nyman’s poll:

Note: original poll page’s here.

Clear enough jQuery rocks. As I personally use jQuery I still think that its success is based on his easy to start nature. However lets see another result chart.

2. Chris Coyier from http://css-tricks.com/ is showing almost the same result:

Note: original poll can be found here.

3. Finally Polldaddy’s hosting a poll, where the results are even more interesting.

Note: original source of the poll.

From these results I get more surprised not so much from the jQuery big advantage, but more from YUI. It’s a really very very powerful JavaScript library, perhaps misunderstood maybe because of it’s native complexity, don’t know?!

If someone asks you what is the javascript in modern web developer, probably you should answer it’s almost the half of the traffic of your site and it’s almost everything when dealing with user experience.

Today’s big web apps are useless without it AJAX/JS part. Think about Facebook, Google products, Twitter, Yahoo!, Youtube.

Actually they made this a standart. The times when you used to use JavaScript as a helper language just to figure out how a drop down menu will work are far way in the past. Now JavaScript is everything in a rich web sites. With no JS they will be no rich at all! Then it comes the question how to improve sites with lots of javascript. Actually one of the main problems in the web now is that JavaScript is blocking content.

Blocked by the JavaScript

What that means at all is that until the browser receives and parses the JavaScript file/s it doesn’t process anything else, it even doesn’t load any other resources. Now you can imagine how big the problem is. When it comes to large files more than 100K the user experience will be very bad!

Optimize the web? What about optimizing JavaScript!

If the problem is so big as I described above why should we doubt about where to start with the optimization process? But of course with the JavaScript and the natural question that rises is how this can be optimized at all?

Three steps

Like me, many of you may heart of some techniques that improve javascript performance. Here are some I was able to select as important:

1. minify/compress

That’s rule number one. If everything that is a JavaScript file is processed once it arrives to the client than make it smaller and make it go faster trough the wire. Actually one technique to speed up things more is to concatenated all the files you have into one single big file. Although this will not spend you some space will reduce the HTTP requests and therefore speed up the loading process. Good tools that you can use to minify javascript files are the Yahoo’s YUI Compressor, that beside that compresses CSS and Google Closure Compiler. Both are extremely useful and by the last measurements the Google’s Compiler is even better, but it’s up to you to decide which one to pick up.

2 .write fast and smart code

You can minify everything that’s JavaScript and the code may remain slow. But why is that? That’s because the JavaScript is written in a bad way. You know there are many resources in the web describing what is a bad and what is a good practice when writing JS. Even more you can measure it by yourself if you’d like to use the Firebug’s profiler. That’s a good start to avoid bad practices.

3. improve loading – lazy loading

That’s a bit more complicated. If there’s a really big javascript file after compressing and concatenating all the JS functionality remains big. How to avoid that? Simply let’s the user to see the most important functionality and than load the entire app. Some good tutorials about lazy loading again can be found online. Don’t hesitate to search about.

Beside this really basic advices I’ll continue to write in my blog about specific techniques how to improve the JavaScript as this is one of the most interesting parts of web development by me.

The problem is that the library supports so many protocols, controls and tools that you probably never use in your application and because of this the size of the resulting, compressed javascript file is around 700K, which is too big for any javascript file at all. That makes your site slow and the user experience is really awful!

The solution is to cut that functionality that you don’t use, which is not so easy. You’ve to be careful doing this, just because you can crash you application by removing something that seems to be useless but in fact isn’t.

I’ve used this technique and managed to make the resulting javascript file up to 400K. And this is really simple – just add the files your application don’t need to the .cfg file you use for compression. Usually this fils is in the /build directory of OpenLayers.

Even more – I’ve seen some other developers managing to reduce the size up to 300K and that’s more than twice which is really very good result.

The other thing I’d like to do with that library is to explore with care the code inside and to optimize anything I can. There are too many style reflows in some classes and that’s what’s visible on the first look. I suppose there are much more things to optimized in it.

I’ll start doing my research and optimization and I’ll let you know what happens in numbers!