gistfile1.js

function Animal(name) {
  this.name = name;
}

Animal.prototype = {
  eat: function() { return this.name + " consumes vital sustenance."; }
};

function Dog(name, breed) {
  this.name = name;
  this.breed = breed;
}

// In stark contrast to classical inheritance, here we are spinning up an "empty"
// Animal object just to use it as the __proto__ of all objects created by Dog
var prototypicalAnimal = new Animal();

Dog.prototype = prototypicalAnimal;

Dog.prototype.bark = function() { return this.name + " barks!"; };
Dog.prototype.procreate = function() { return "A new " + this.breed + " is born."; };

console.log(dog.eat()); //=> Bozo consumes vital sustenance.
console.log(dog.bark()); //=> Bozo barks!
console.log(dog.procreate()); //=> A new terrier is born.