A Javascript inheritance function. Derived by joining some parts by John Resig http://ejohn.org/ and some by Ajax.org Code Editor (ACE) Source. The end result: When you call `inherits` each overridden method in the derived class can call it's super-method by using this._super.

inheritance.js

/* JavaScript Inheritance
 * Author: Mutahhir Ali Hayat
 * Made by joining some parts by John Resig http://ejohn.org/ and some by Ajax.org Code Editor (ACE)
 */

define(function(require, exports, module) {
    var initializing = false,
    fnTest = /xyz/.test(function() {
        xyz;
    }) ? /\b_super\b/: /.*/;


  exports.inherits = (function() {
		var tempCtor = function() {};
		return function(ctor, superCtor) {
			tempCtor.prototype= superCtor.prototype;
			var	prop = ctor.prototype,
				_super = superCtor.prototype,
				prototype = new tempCtor();
				
			for(var name in prop) {
				prototype[name] = 
					typeof prop[name] === "function" && 
					typeof _super[name] === "function" && 
					fnTest.test(prop[name])? 
							(function(name, fn){
								return function(){ 
									var tmp = this._super;
									this._super = _super[name];
									var ret = fn.apply(this, arguments);
									this._super = tmp;
									return ret;
								}
							})(name, prop[name]) : prop[name];	
			}
			
			ctor.prototype = prototype;
			ctor.prototype.constructor = ctor;
			
			return ctor;
		}
	})();
});

sample_use.js

/* ---- 
  This is an excerpt from a javascript library called Cotton I made. Not opensourced yet.
   
  Layer is the base class and Stack is the derived class.
  
	Just FYI: A stack is a kind of layer that automatically ensures that all children are placed vertically one after the other

 ---- */
define(function(require, exports, module) {
	
	var oop = require("cotton/oop");
	var Layer = require('cotton/layer').Layer;
	
	var Stack= function(parent, options){
		if (!(this instanceof Stack)) {
			return new Stack(parent, options);
		}
		
		Layer.apply(this, arguments);
	};
	
	(function(){
		// add prototype functions here
		this._createElement = function _createElement() {
			var el = this._super.apply(this, arguments);
			
			$(el).addClass('stack');
			return el;
		};
		
	}).call(Stack.prototype);
	
	oop.inherits(Stack, Layer);
	
	exports.Stack = Stack;
	
});