Factory Pattern

function Car(options) {
    this.doors = options.doors || 4;
    this.color = options.color || "white";
    this.state = options.state || "brand new";
}

function Truck(options) {
    this.wheelSize = options.wheelSize || 4;
    this.color = options.color || "black";
    this.state = options.state || "used";
}

function VehicleFactory() { };

// default vahicle class
VehicleFactory.prototype.vehicleClass = Car;

VehicleFactory.prototype.createVehicle = function (options) {
    if (options.vehicleType === "car") {
        this.vehicleClass = Car;
    } else {
        this.vehicleClass = Truck;
    }

    return new this.vehicleClass(options);
};

var carFactory = new VehicleFactory();
var car = carFactory.createVehicle({
    vehicleType: "car",
    doors: 5,
    color: "red"
});

console.log(car instanceof Car);
console.log(car);

//modify
var movingTruck = carFactory.createVehicle({
    vehicleType: "truck",
    wheelSize: 8,
    color: "blue"
});

console.log( movingTruck instanceof Truck );
console.log(movingTruck);

// new factory for trucks
function TruckFactory () {}
TruckFactory.prototype = new VehicleFactory();
TruckFactory.prototype.vehicleClass = Truck;

var truckFactory = new TruckFactory();
var myBigTruck = truckFactory.createVehicle( {
    state: "bad",
    color: "pink",
    wheelSize: "big" } );

console.log( myBigTruck instanceof Truck );
console.log( myBigTruck );