js 模板方法模式

* 分离出共同点

function Beverage() {}

Beverage.prototype.boilWater = function() {
	console.log("把水煮沸");
}

Beverage.prototype.brew = function() {
	throw new Error('子类必须重写brew方法');
}

Beverage.prototype.pourInCup = function() {
	throw new Error('子类必须重写pourInCup方法');
}

Beverage.prototype.addCondiments = function() {
	throw new Error('子类必须重写addCondiments方法');
}

Beverage.prototype.init = function() {
	this.boilWater();
	this.brew();
	this.pourInCup();
	this.addCondiments();
}

function Coffee() {}

Coffee.prototype = new Beverage();

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 coffee = new Coffee();
// coffee的原型Coffee没有init方法, 
// 顺着原型链委托给父类的Beverage原型上的init方法
coffee.init();

console.log("-------------------------");

function Tea() {}

Tea.prototype = new Beverage();

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("加柠檬");
}

var tea = new Tea();
tea.init();