Prototype chains + constructor-based initialization using Object.create

ObjectDotCreate.js

//Animal constructor
function Animal( legCount ){
  this.legCount = legCount;
}
 
//Methods
Animal.prototype.legCount = function(){
  return( this.legCount );
};

////////////////////////////////////////////////////////////////////////////////

//bird  constructor
function Bird(){
  // Call the super constructor.
  Person.call( this, 2);
  // Create the traits property.
  this.traits = {};
}

//Extend the animal prototype using object.create.
Bird.prototype = Object.create( Animal.prototype );

//Another method here.
Bird.prototype.chant = function(){
  return 'blablabla';
}

// Create a bird instance
var parrot = new Bird();
parrot.traits.color = 'rainbow';
parrot.traits.diet = 'fruits';
 
// Create  another bird instance
var hawk = new Bird();
hawk.traits.color = 'gray';
hawk.traits.diet = 'meat';

//////////////////////////////////////////////////////////////////////////////// 

function Mammal(){
  Animal.call(this, 4);
}

Mammal.prototype = Object.create(Animal.prototype)

//etc..

////////////////////////////////////////////////////////////////////////////////