oop - How can I split a javascript application into multiple files?

Question

I created a javascript application with all of the code in one file. The application has grown quite a bit and I think it's time to split it up into multiple files, but I'm having a hard time figuring out how to do this. I think the problem lies with how I have decided to build the app, which uses the following template:

var myApp = function(){

    //there are several global variables that all of the modules use;
    var global1, global2, module1, module2;

    global1 = {
        prop1:1
    };

    //There are also several functions that are shared between modules
    function globalFunction(){

    }

    var ModuleOne = function(){

        function doSomething(){
            //using the global function
            globalFunction();
        }

        return{
            doSomething:doSomething
        }
    };

    var ModuleTwo = function(){

        function doSomething(){
            //module 2 also needs the global function
            globalFunction();

            //Use the functionality in module 1
            //I can refactor this part to be loosely coupled/event driven
            module1.doSomething();
        }
    };

    module1 = new ModuleOne();
    module2 = new ModuleTwo();
};

Even if all of the modules were loosely coupled and event driven, I still don't know how I would go about splitting this into multiple files given each module's reliance on the shared functions/variables. Does anyone have suggestions?

Answer 1

Take a look at the design pattern in this article: http://www.adequatelygood.com/2010/3/JavaScript-Module-Pattern-In-Depth - you can split your module definition across multiple files in a way that lets common properties be shared but also lets you create variables or methods that are private just to a particular file.

The basic idea is that the individual JS files add to the same module with code like this:

var MODULE = (function (my) {
     var privateToThisFile = "something";

    // add capabilities...

     my.publicProperty = "something";

    return my;
}(MODULE || {}));

Where in each JS file if MODULE is already defined (from another JS file) you add to it otherwise you create it. You can set it up so that it (mostly) doesn't matter what order the various files are included in.

The article details several variations, and of course you'll probably come up with your own tweaks...