JavaScript Prototypal Inheritance + Calling Parent Constructors

inheritAnimals.js

// https://speakerdeck.com/u/anguscroll/p/how-we-learned-to-stop-worrying-and-love-javascript

var Animal = function(gender, says) {
  this.gender = gender;
  this.says = says;
};

Animal.prototype.speak = function() {
  console.log(this.says);
};

var WalkingAnimal = function(gender, says) {
  Animal.call(this, gender, says);
};

WalkingAnimal.prototype = new Animal();

WalkingAnimal.prototype.walk = function() {
  console.log('walking');
};
WalkingAnimal.prototype.turn = function(direction) {
  console.log('turning', direction);
};
WalkingAnimal.prototype.stop = function() {
  console.log('stopped walking');
};

var Elephant = function(gender) {
  WalkingAnimal.call(this, gender, "whoooop");
}

Elephant.prototype = new WalkingAnimal();
Elephant.prototype.doCleverThingsWithTrunk = function() {
  console.log("doing clever things with trunk");
}

var karela = new Elephant("male");
karela.walk();
karela.turn("right");
karela.stop();
karela.speak();