node.js如何实现装饰者模式

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());