Copy and extend global objects in javascript

Question

Hi, is there a way to copy a global object (Array,String...) and then extend the prototype of the copy without affecting the original one? I've tried with this:

var copy=Array;
copy.prototype.test=2;

But if i check Array.prototype.test it's 2 because the Array object is passed by reference. I want to know if there's a way to make the "copy" variable behave like an array but that can be extended without affecting the original Array object.

Answer 1

Good question. I have a feeling you might have to write a wrapper class for this. What you're essentially doing with copy.prototype.test=2 is setting a class prototype which will (of course) be visible for all instances of that class.

Answer 2

Instead of extending the prototype, why don't you simply extend the copy variable. For example, adding a function

copy.newFunction = function(pParam1) { 
      alert(pParam1);
};