factory_pattern.js

function CarDoor(options) {
	this.color = options.color || "red";
	this.side = options.side || "right";
	this.hasPowerWindows = options.hasPowerWindows || true;
}

function CarSeat(options) {
	this.color = options.color || "gray";
	this.material = options.material || "leather";
	this.isReclinable = options.isReclinable || true;
}

function CarPartFactory() {}

CarPartFactory.prototype.createPart = function(options) {
	
	var parentClass = null;
  
	  if( options.partType === 'door' ) {
	    parentClass = CarDoor;
	  } else if( options.partType === 'seat' ) {
	    parentClass = CarSeat;
	  }
  
	  if( parentClass === null ) {
	    return false;
	  }
  
	  return new parentClass( options );
	
}

var myPartFactory = new CarPartFactory();
var seat = myPartFactory.createPart( {
  partType : 'seat',
  material : 'leather',
  color : 'blue',
  isReclinable : false
} );
 
// outputs: true
console.log( seat instanceof CarSeat );
 
// outputs a CarSeat object with material "leather", color "blue", isReclinable "false"
console.log( seat );