Basic JS inheritance

gistfile1.js

// Constructor function. Code run by the "new" operator
var Rabbit = function(name) {
	// All Rabbit instances have their own property "name"
	this.name = name;
}

// All Rabbit instances can speak, of course!
Rabbit.prototype.speak = function(what) {
	return this.name + " says: " + what;
}

// Constructor function for Killer Rabbits
var KillerRabbit = function(name, eyes) {
	Rabbit.call(this, name); // Call parent constructor
	this.eyes = eyes;
}

// Make this have a "Rabbit" prototype
KillerRabbit.prototype = new Rabbit();

// The constructor needs to be fixed :)
KillerRabbit.prototype.constructor = KillerRabbit;

// Add your own sauce now!
KillerRabbit.prototype.kill = function(who) {
	return this.eyes + "-eyed " + this.name + " killed: " + who;
}

// And now use it!
var caerbannog = new KillerRabbit("Vorpal", "Red");

// Some checks before killing anyone!
caerbannog instanceof Object; // true
caerbannog instanceof Rabbit; // true
caerbannog instanceof KillerRabbit; // true

// Unleash the rabbit!
caerbannog.speak("Hi!"); // "Vorpal says: Hi!"
caerbannog.kill("Churches"); // "Red-eyed Vorpal killed: Churches"

// Last check!
var roger = new Rabbit("Roger");
roger instanceof KillerRabbit; // false

// Applause!