Object-Oriented JavaScript

Isolating the Inheritance Part into a Function

Let's move the code that takes care of all of the inheritance details into a reusable extend() function:

function extend(Child, Parent) {
  var F = function(){};
  F.prototype = Parent.prototype;
  Child.prototype = new F();
  Child.prototype.constructor = Child;
  Child.uber = Parent.prototype;
}

Using this function (or your own custom version of it) will help you keep your code clean with regard to the repetitive inheritance-related tasks. This way you can inherit by simply using:

extend(TwoDShape, Shape);

and

extend(Triangle, TwoDShape);

This approach is the way the YUI (Yahoo! User Interface) library implements inheritance through its extend() method. For example, if you use YUI and you want your Triangle