JS шаблон стратегия

factory.js

//способ первый
function ShapeFactory(size, color)
{
    this.size = size;
    this.color = color;
}
 
ShapeFactory.prototype =
{
    constructor: ShapeFactory,
 
    makeCircle: function () { return new Shapes.Circle({ radius: this.size / 2, color: this.color }); },
    makeSquare: function () { return new Shapes.Square({ side: this.size, color: this.color }); },
    makeTrinagle: function () { return new Shapes.Triangle({ side: this.size, color: this.color }); }
}
 
//способ второй
function PetFactory() {
};
 
PetFactory.register = function(name, PetConstructor) {
  if (name instanceof Function) {
    PetConstructor = name;
    name = null;
  }
 
  if (!(PetConstructor instanceof Function)) {
    throw {
      name: 'Error',
      message: 'PetConstructor is not function'
    }
  }
  this[name || PetConstructor.name] = PetConstructor;
};
 
PetFactory.create = function(petName) {
  var PetConstructor = this[petName];
  if (!(PetConstructor instanceof Function)) {
    throw {
      name: 'Error',
      message: 'constructor "' + petName + '" undefined'
    }
  }
  return new PetConstructor();
};