var Beverage = function(){};

Beverage.prototype.boilWater = function(){
	console.log("把水煮沸");
};
Beverage.prototype.brew = function(){
	throw new Error("子类必须重写该方法");
};
Beverage.prototype.pourInCup = function(){
	throw new Error("子类必须重写该方法");
};
Beverage.prototype.addCondiments = function(){
	throw new Error("子类必须重写该方法");
};
Beverage.prototype.customerWantsCondiments = function(){
	return true;
};
Beverage.prototype.init = function(){
	this.boilWater();
	this.brew();
	this.pourInCup();
	if(this.customerWantsCondiments){
		this.addCondiments();
	}
};

var Coffee = function(){};
Coffee.prototype = new Beverage();//继承父类Beverage
Coffee.prototype.boilWater = function(){
	console.log("把水煮沸");
};
Coffee.prototype.brew = function(){
	console.log("用沸水冲泡咖啡");
};
Coffee.prototype.pourInCup = function(){
	console.log("把咖啡倒进杯子");
};
Coffee.prototype.addCondiments = function(){
	console.log("加糖和牛奶");
};

var Tea = function(){};
Tea.prototype = new Beverage();//继承父类Beverage
Tea.prototype.boilWater = function(){
	console.log("把水煮沸");
};
Tea.prototype.brew = function(){
	console.log("用沸水浸泡茶叶");
};
Tea.prototype.pourInCup = function(){
	console.log("把茶水倒进杯子");
};
Tea.prototype.addCondiments = function(){
	console.log("加入柠檬");
};
Tea.prototype.customerWantsCondiments = function(){
	return window.confirm("请问需要加调料吗?");
};

var coffee = new Coffee();//实例化Coffee
coffee.init();

var tea = new Tea();//实例化Tea
tea.init();