JavaScript, Inheritance: John Resig Simple Inheritance

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    /* Simple JavaScript Inheritance
     * By John Resig http://ejohn.org/
     * MIT Licensed.
     */
    // Inspired by base2 and Prototype
    (function(){
      var initializing = false, fnTest = /xyz/.test(function(){xyz;}) ? /\b_super\b/ : /.*/;
     
      // The base Class implementation (does nothing)
      this.Class = function(){};
     
      // Create a new Class that inherits from this class
      Class.extend = function(prop) {
        var _super = this.prototype;
       
        // Instantiate a base class (but only create the instance,
        // don't run the init constructor)
        initializing = true;
        var prototype = new this();
        initializing = false;
       
        // Copy the properties over onto the new prototype
        for (var name in prop) {
          // Check if we're overwriting an existing function
          prototype[name] = typeof prop[name] == "function" &&
            typeof _super[name] == "function" && fnTest.test(prop[name]) ?
            (function(name, fn){
              return function() {
                var tmp = this._super;
               
                // Add a new ._super() method that is the same method
                // but on the super-class
                this._super = _super[name];
               
                // The method only need to be bound temporarily, so we
                // remove it when we're done executing
                var ret = fn.apply(this, arguments);        
                this._super = tmp;
               
                return ret;
              };
            })(name, prop[name]) :
            prop[name];
        }
       
        // The dummy class constructor
        function Class() {
          // All construction is actually done in the init method
          if ( !initializing && this.init )
            this.init.apply(this, arguments);
        }
       
        // Populate our constructed prototype object
        Class.prototype = prototype;
       
        // Enforce the constructor to be what we expect
        Class.prototype.constructor = Class;
     
        // And make this class extendable
        Class.extend = arguments.callee;
       
        return Class;
      };
    })();