Constructors used behind the scenes - Node.js Object

Node.js examples for Object:Constructor

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Description

Constructors used behind the scenes

Demo Code


// Types.js - Constructors used behind the scenes
 
// A constructor for defining new cars
function Car( options ) {
 
  // some defaults
  this.doors = options.doors || 4;//  w  w w  . ja  v a 2s .  c  om
  this.state = options.state || "brand new";
  this.color = options.color || "silver";
 
}
 
// A constructor for defining new trucks
function Truck( options){
 
  this.state = options.state || "used";
  this.wheelSize = options.wheelSize || "large";
  this.color = options.color || "blue";
}
 
 
// FactoryExample.js
 
// Define a skeleton vehicle factory
function VehicleFactory() {}
 
// Define the prototypes and utilities for this factory
 
// Our default vehicleClass is Car
VehicleFactory.prototype.vehicleClass = Car;
 
// Our Factory method for creating new Vehicle instances
VehicleFactory.prototype.createVehicle = function ( options ) {
 
  switch(options.vehicleType){
    case "car":
      this.vehicleClass = Car;
      break;
    case "truck":
      this.vehicleClass = Truck;
      break;
    //defaults to VehicleFactory.prototype.vehicleClass (Car)
  }
 
  return new this.vehicleClass( options );
 
};
 
// Create an instance of our factory that makes cars
var carFactory = new VehicleFactory();
var car = carFactory.createVehicle( {
            vehicleType: "car",
            color: "yellow",
            doors: 6 } );
 
// Test to confirm our car was created using the vehicleClass/prototype Car
 
// Outputs: true
console.log( car instanceof Car );
 
// Outputs: Car object of color "yellow", doors: 6 in a "brand new" state
console.log( car );


--------------------------------------------------------------------------------

function TruckFactory () {}
TruckFactory.prototype = new VehicleFactory();
TruckFactory.prototype.vehicleClass = Truck;
 
var truckFactory = new TruckFactory();
var myBigTruck = truckFactory.createVehicle( {
                    state: "omg..so bad.",
                    color: "pink",
                    wheelSize: "so big" } );
 
// Confirms that myBigTruck was created with the prototype Truck
// Outputs: true
console.log( myBigTruck instanceof Truck );
 
// Outputs: Truck object with the color "pink", wheelSize "so big"
// and state "omg. so bad"
console.log( myBigTruck );

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