Javascript Module pattern, Prototype and Google Closure

Question

I am having trouble getting this code structure to survive obfuscation with the Google Closure Compiler. Here's some sample code:

var MyModule = (function()
{   
    function myModule()
    {
        // Constructor
    }

    function moduleFoo(url)
    {
        // Method
    }

    function moduleBar()
    {
        // Method
    }

    myModule.prototype = {
        constructor: myModule,
        foo: moduleFoo,
        bar: moduleBar
    };

    return myModule;

})();

Elsewhere in my code I need be able to write things like the following:

var myMod = new MyModule();
myMod.foo();
myMod.bar();

However the compiler is renaming everything (as expected). How can I make the prototype that I have defined available elsewhere in my code after obfuscation? I have tried exporting as follows:

// In place of the prototype object above
myModule.prototype['constructor'] = myModule;
myModule.prototype['foo'] = moduleFoo;
myModule.prototype['bar'] = moduleBar;

window['myModule'] = myModule;

But things seem to break down either when the prototype methods are called or when their corresponding closures are executed.

Any help is appreciated.

Answer 1

This exact pattern does not work well with Closure-compiler using ADVANCED_OPTIMIZATIONS. Instead, you will need to slightly refactor your code:

/** @constructor */
function MyModule()
{
    // Constructor
}

(function() {
    function moduleFoo(url)
    {
        // Problem using "this" keyword. Will require @this annotation.
    }

    MyModule.prototype = {
        foo: moduleFoo
    };

    MyModule.prototype.bar =  function() {
        // "this" keyword works fine.
    };
})();

Or like:

/** @const */
var MyNamespace = {};

(function() {
    /** @constructor */
    MyNamespace.MyModule = function() {};

    MyNamespace.MyModule.prototype = {
        constructor: function() {},
        foo: function(url) {},
        bar: function() {}
    };
})();

With either of the above methods your exports should work correctly.

Note: The second option will only work with a compiler built from the latest source as it involves a bug that was just fixed last week.