Loading dependencies in JavaScript

Isn't it nice to work modularized, even in JavaScript?
I like putting all my classes in their own files and all the little functions that don't belog to any class in a file called toolbox.js

That's pretty neat and organized, but when it comes to inserting all the necessary js files into your webpage, it's a pain, isn't it?

Well, not for me. I add the toolbox.js to every webpage that uses JavaScript and then the most important js file for that particular page.

Here's an example; I have a webpage that needs to use the EntryModule class. But this class needs a few more classes that are stored in other files, the TableEntryClass, the TextEntryClass and ColourObjectClass. All I need to do is to call this function:

loadDependencies(Array('js/ColourObjectClass.js', 'js/TableEntryClass.js', 'js/TextEntryClass.js'));

This function takes either a string or an array of strings that specify the js files to add to the same webpage that loaded EntryModuleClass.js

Here's the code, use it wise:

function loadDependencies(dependency)
{
  var head = document.getElementsByTagName('head')[0];
   var scripts = head.getElementsByTagName('script');
  var i, j, newjs;
  if(typeof dependency == 'string')
  {
    //search if it's loaded already
    for(i=0; i < scripts.length; ++i)
      if(scripts[i].src.toLowerCase() == dependency.toLowerCase())
        return;
    //if not, load it
    newjs = document.createElement('script');
    newjs.type = 'text/javascript';
    newjs.src = dependency;
    head.appendChild(newjs);
  }
  if(typeof dependency == 'object')//it must be an array
  {
     //search if it's loaded already
     for(i=0; i < dependency.length; ++i)
     {
       for(j=0; j < scripts.length; ++j)
         if(scripts[j].src.toLowerCase() == dependency[i].toLowerCase())
           return;
       //if not, load it
       newjs = document.createElement('script');
       newjs.type = 'text/javascript';
       newjs.src = dependency[i];
       head.appendChild(newjs);
     }
   }
}

I hope you notice the care I took with declaring the variables at the begining of the function and also getting the head tag and the script tags at the begining to optimize the number of searches...