closure_factory.js

var animal = {
  animalType: 'animal'
};

function catFactory(name) {
  var _name = name;

  newCat = Object.create(animal);
  newCat.animalType = 'cat';
  newCat.setName = function(name) {
    _name = name;
  };
  newCat.getName = function() {
    return _name;
  };

  return newCat;
};

var myCat = catFactory("Mr. Jones");

myCat.animalType; // => "cat"
Object.getPrototypeOf(myCat).animalType; // => "animal"
myCat.getName(); // => "Mr. Jones"
myCat._name; // => undefined