node.js实现的装饰者模式示例

var util = require('util');var Beverage = function(){  var description = "Unkown Beverage"  this.getDescription = function(){    return description;  }}function Espresso(){  Beverage.call(this);  this.description = "Espresso";}util.inherits(Espresso, Beverage);Espresso.prototype.cost = function(){  return 1.99;}function HouseBlend(){  Beverage.call(this);  this.description = "House Blend Coffee";}util.inherits(HouseBlend, Beverage);HouseBlend.prototype.cost = function(){  return .89;}function Mocha(beverage){  this.beverage = beverage;};Mocha.prototype.getDescription = function(){  return this.beverage.getDescription() + ", Mocha";}Mocha.prototype.cost = function(){  return 0.20 + this.beverage.cost();}function Whip(beverage){  this.beverage = beverage;};Whip.prototype.getDescription = function(){  return this.beverage.getDescription() + ", Whip";}Whip.prototype.cost = function(){  return 0.40 + this.beverage.cost();}var beverage = new Espresso();console.log(beverage.getDescription() + " $" + beverage.cost());var beverage2 = new HouseBlend();beverage2 = new Mocha(beverage2);beverage2 = new Mocha(beverage2);beverage2 = new Whip(beverage2);console.log(beverage2.getDescription() + " $" + beverage2.cost());