Simple javascript inheritance (as i currently understand it)

inheritance.js

var Mammal = function (name) {
  this.name = name;
};

Mammal.prototype.sayHello = function () {
  return "Hello, I'm a " + this.name;
}

var Cow = function (name) {
  Mammal.apply(this, arguments);
};

Cow.prototype = new Mammal();
Cow.prototype.constructor = Cow;

// Usage example
var jerseyCow = new Cow("jersey cow");
console.info(jerseyCow.sayHello());

var magicCow = new Cow("magic cow");
console.info(magicCow.sayHello());