Inheritance and Polymorphism in Javascript

You must read http://aspnettechstuffs.blogspot.com/2010/05/inheritance-in-javascript.html before going further, I am going to use example from that

creating person class

function Person()

{

    this.eyes = 2;

    this.legs = 2;

    this.color = "white";

}

Inheriting Man class from Person

Man.prototype.constructor = Man; 

Man.prototype = new Person;

writing Man class now

function Man()

{

    this.color = "black";

}

Adding few properties in prototypes directly

Person.prototype.legs = 4;

Man.prototype.legs = 2;

Man.prototype.hair = "black";

creating objects

var p = new Person;

var m = new Man;

The prototype chain for m will look as following

On the same line you can create prototype chain for object p. Now to verify if your objects are actually inherited try following

alert(m instanceof Man);  //will pop up true

alert(m instanceof Person); // will pop up true

Reference: http://mckoss.com/jscript/object.htm