Functional and Pseudoclassical classes

classes.js

//==================================
// Functional classes
// Define methods inside the object constructing function

var makeAnimal = function(name){
  var obj = {};
  obj.name = name;
  var privateVar = 'you can see me';
  
  obj.speak = function () {
    //privateVar is accessible through closure
    console.log('Hi I am', obj.name, privateVar); //Hi I am duck you can see me
  };
  
  return obj;
};

var duck = makeAnimal('duck');
duck.speak();
//===================================
// Functional-shared classes (a variation of the Functional class)
// Define methods outside in another object to avoid creating multiple copies of functions through instantiation 
var makeAnimalShared = function(name){
  var obj = {};
  obj.name = name;
  var privateVar = 'you cant see me';
  
  obj.speak = AnimalMethods.speak; //Hi I am horse undefined
  
  return obj;
};

var AnimalMethods = {
  speak: function(){
    //privateVar is not accessible when the method is defined outside object constructing function
    console.log('Hi I am', this.name, this.privateVar);
  }
};
var horse = makeAnimalShared('horse');
horse.speak();


//====================================
var Animal = function(name){
  //var this = Object.create(Animal.prototype); //added by JS compiler when invoked with 'new'
  this.name = name;
  var privateVar = 'you cant see me';
  //return this;   //added by JS compiler when invoked with 'new'
};
// All the JS functions by default have the prototype property for aggregating methods
Animal.prototype.speak = function(){
  //privateVar is not accessible if it is not associated with the instance through 'this'
  console.log('Hi I am', this.name, this.privateVar); //Hi I am dragon undefined
};

// When an instance is created using 'New' keyword, the statements in line 45 and line 48 are automatically added by the compiler 
// 
var dragon = new Animal('dragon'); 
dragon.speak();