Setting up prototypal inheritance in JavaScript

prototypal-inheritance.js

var Animal = {
    type: 'mammal',
    legs: 4,
    eyes: ['blue', 'black', 'brown'],
    saying: ''
};

console.log(Animal.constructor); //	Refers to the constructor method on the Object

Animal.prototype = {
    constructor: Animal, 	//	Reset the constructor on the child (of Object class) literal
    say: function() {
        console.log(this.saying);
    }
};

var Cat = Object.create(Animal);
var Dog = Object.create(Animal);

console.log(Object.keys(Cat));	// 	= [], empty because Cat only has inherited props,
console.log(Object.keys(Object.getPrototypeOf(Cat)));
console.log(Object.keys(Cat.__proto__));

Cat.saying = 'meow';
Cat.say = function() {		//	Overwrites inherited Animal say method
   Animal.prototype.say.apply(this, Array.prototype.slice(arguments));
};

Cat.say();			//	logs meow
console.log(Cat.legs);		//	logs 4

Cat.eyes[0] = 'grey';		//	mutating the inherited mutable props are mutated across all instances

console.log(Dog.eyes[0]);	//	grey

Cat.eyes = ['green'];		//	replacing the inherited mutable props are overriden for specific instance

console.log(Dog.eyes[0]); 	//	still grey
console.log(Cat.eyes[0]); 	//	green

//  console.log(Cat.prototype.ears);
//  Whatever is defined in the parent Object literal (Super class) prototype is available as Child object literal's (Sub class) prototype. If the S
//  Whatever is defined on the parent Object literal (Super class) is available on the child Object literal (via parent's prototype) created with Object.create