​

// function for extending a class

function extend (base, constructor) {

  var prototype = new Function();

  prototype.prototype = base.prototype;

  constructor.prototype = new prototype();

  constructor.prototype.constructor = constructor;

}

​

// parent class

function Animal (name) {

  this.animalName = name;

  console.log("////== Animal Constructor ==/////");

  console.log("An animal named " + name);

}

​

Animal.prototype.makeNoise = function (noise) {

  console.log("////== Animal makeNoise() ==////");

  console.log(noise + ", I can make noise...");

};

​

// subclass

function Dog (name) {

  // call the super

  Animal.call(this, name);

  console.log("////== Dog Constructor ==/////");

  console.log("I am a Dog named " + this.animalName);

}

​

// important that this happens before you override methods on parent class

extend(Animal, Dog);

​

Dog.prototype.makeNoise = function (noise) {

  Animal.prototype.makeNoise.call(this, noise);

  console.log("////== Dog makeNoise() ==////");

  console.log("I am a Dog, I like to " + noise);

};

​

// Usage

var dog = new Dog("Sparky");

dog.makeNoise("Bark!!");

​