factory-design-pattern-es5.js

// public method
function Bike() {}

Bike.prototype.ride = function () {
  return "I ride " + this.brand;
};

// static method
function BikeMaker() {}
BikeMaker.factory = function (brandname) {
  if (typeof BikeMaker[brandname] !== "function") {
    throw {
      name: "Error",
      message: brandname + " does not exist",
    };
  }

  if (typeof BikeMaker[brandname].prototype !== "function") {
    BikeMaker[brandname].prototype = new Bike();
  }
  return new BikeMaker[brandname]();
};

BikeMaker.giant = function () {
  this.brand = "Giant";
};

BikeMaker.merida = function () {
  this.brand = "Merida";
};

var mybike = BikeMaker.factory("giant");
var yourbike = BikeMaker.factory("merida");
console.log(mybike.ride()); // This bike is Giant
console.log(yourbike.ride()); // This bike is Merida