JavaScript 设计模式 - 原型模式

原型模式

原型模式用于创建一个可以被其他对象继承的对象。这种模式通过JavaScript原生内置的原型继承很容易实现。

• 在原型上创建方法

function Welcome(name) {
  this.name = name;
}
Welcome.prototype.sayHello = function() {
  return 'Hello, ' + this.name + '!';
}

var welcome = new Welcome('John');

welcome.sayHello();
// => Hello, John!

• 原型继承

function RoomService(name, order) {
  // this.name will be set and made available on the scope of this function
  Welcome.call(this, name);
  this.order = order;
}

// Inherit 'sayHello()' methods from 'Welcome' prototype
RoomService.prototype = Object.create(Welcome.prototype);
// By default prototype object has 'constructor' property. 
// But as we created new object without this property  -  we have to set it manually,
// otherwise 'constructor' property will point to 'Welcome' class
RoomService.prototype.constructor = RoomService;
RoomService.prototype.announceDelivery = function() {
  return 'Your ' + this.order + ' has arrived!';
}
RoomService.prototype.deliverOrder = function() {
  return this.sayHello() + ' ' + this.announceDelivery();
}

var delivery = new RoomService('John', 'pizza');

delivery.sayHello();
// => Hello, John!,

delivery.announceDelivery();
// Your pizza has arrived!

delivery.deliverOrder();
// => Hello, John! Your pizza has arrived!