Flyweight factory with cloning (credit Eric Elliott)

var carPrototype = {
    gas: function gas(amount) {
      amount = amount || 10;
      this.mph += amount;
      return this;
    },
    brake: function brake(amount) {
      amount = amount || 10;
      this.mph = ((this.mph - amount) < 0)? 0
        : this.mph - amount;
      return this;
    },
    color: 'pink',
    direction: 0,
    mph: 0
  },

  car = function car(options) {
    return extend(Object.create(carPrototype), options);
  },

  myCar = car({
    color: 'red'
  });

test('Flyweight factory with cloning', function () {
  ok(Object.getPrototypeOf(myCar).gas,
    'Prototype methods are shared.'
  );
});