Functional instantiation with shared methods

gistfile1.js

// Makes two animals that have their own animal sound methods, but share a common .eat method

var makeCat = function(){
  var cat = {};
  cat.stomach = [];
  cat.meow = function(){
    console.log("MEOW");
  };
 
  _.extend(cat, animalMethods);
  return cat;
};

var makeDog = function (){
  var dog = {};
  dog.stomach = [];
  dog.bark = function(){
    console.log("WOOFWOOF");
  };
  
  _.extend(dog, animalMethods)
  return dog;
};

var animalMethods = {
  
  eat: function(food){
    this.stomach.push(food);
  }

};
 
var kitty = makeCat();
var pupDog = makeDog();

kitty.meow(); // "MEOW"
pupDog.bark(); // "WOOFWOOF"
 
kitty.eat('owner');
console.log(kitty.stomach); // ["owner"]          

pupDog.eat('kitty');
console.log(pupDog.stomach); // ["kitty"]