javascript - loading js files and other dependent js files asynchronously

Question

I'm looking for a clean way to asynchronously load the following types of javascript files: a "core" js file (hmm, let's just call it, oh i don't know, "jquery!" haha), x number of js files that are dependent on the "core" js file being loaded, and y number of other unrelated js files. I have a couple ideas of how to go about it, but not sure what the best way is. I'd like to avoid loading scripts in the document body.

So for example, I want the following 4 javascript files to load asynchronously, appropriately named:

/js/my-contact-page-js-functions.js // unrelated/independent script
/js/jquery-1.3.2.min.js // the "core" script
/js/jquery.color.min.js // dependent on jquery being loaded
http://thirdparty.com/js/third-party-tracking-script.js // another unrelated/independent script

But this won't work because it's not guaranteed that jQuery is loaded before the color plugin...

(function() {
    var a=[
      '/js/my-contact-page-functions.js',
      '/js/jquery-1.4.2.min.js',
      '/js/jquery.color.js',
      'http://cdn.thirdparty.com/third-party-tracking-script.js',
    ],
    d=document,
    h=d.getElementsByTagName('head')[0],
    s,
    i,
    l=a.length;
    for(i=0;i<l;i++){
        s=d.createElement('script');
        s.type='text/javascript';
        s.async=true;
        s.src=a[i];
        h.appendChild(s);
    }
})();

Is it pretty much not possible to load jquery and the color plugin asynchronously? (Since the color plugin requires that jQuery is loaded first.)

The first method I was considering is to just combine the color plugin script with jQuery source into one file.

Then another idea I had was loading the color plugin like so:

$(window).ready(function() {
    $.getScript("/js/jquery.color.js");
});

Anyone have any thoughts on how you'd go about this? Thanks!

Answer 1

LABjs is made specifically for this problem.

<script src="lab.js"></script>
<script>
  $LAB
    .script("jquery.js")
    .wait()
    .script("jquery.color.js")
    .script("jquery.otherplugin.js")
    .script("mylib.js")
    .wait()
    .script("unrelated1.js")
    .script("unrelated2.js");
</script>

You could also put the unrelated scripts into their own $LAB chain, if they really have no need to wait for jQuery and your other scripts.