JavaScript模板方法模式与职责链模式实战解析

//创建抽象类 -- 饮料
     function Beverage(){}
     Beverage.prototype.boilWater = function(){
         console.log("把水煮沸")
     }
     //抽象的父类方法，具体实现由子类来写
     Beverage.prototype.brew = function(){} //泡
     Beverage.prototype.pourIncup = function(){} //饮料倒进杯子
     Beverage.prototype.addCond = function(){} //加调料
     Beverage.prototype.init = function(){
         this.boilWater();
         this.brew();
         this.pourIncup();
         this.addCond();
     }
     //创建具体子类 coffee and tea
     var Coffee = function (){};
     Coffee.prototype = new Beverage();
     Coffee.prototype.brew = function (){
         console.log("用沸水冲泡咖啡")
     }
     Coffee.prototype.brew = function (){
         console.log("把咖啡倒进杯子")
     }
     Coffee.prototype.brew = function (){
         console.log("加糖和牛奶")
     }
     var coffee = new Coffee();
     coffee.init();
     var Tea = function(){};
     Tea.prototype = new Beverage();
     Tea.prototype.brew = function (){
         console.log("用沸水冲泡茶")
     }
     Tea.prototype.brew = function (){
         console.log("茶倒进杯子")
     }
     Tea.prototype.brew = function (){
         console.log("加柠檬")
     }
     var tea= new Tea();
     tea.init();

Beverage.prototype.brew = function (){
    throw new Error("子类必须重写父类的brew方法")
}

 //旧版 order
        //orderType 预付定金类型，code为1 500元定金 code为2 200元定金 code为3 普通用户
        //pay 是否已经支付过定金
        //stock  当前用于普通购买客户的手机内存数量
        var order = function (orderType, pay, stock) {
            if (orderType === 1) {
                if (pay) {
                    console.log("预付500定金并且已支付，得到100元优惠券")
                } else { //定金未支付，降到普通购买
                    if (stock > 0) {
                        console.log("普通购买，无优惠券")
                    } else {
                        console.log("库存不足");
                    }
                }
            }
            if (orderType === 2) {
                if (pay) {
                    console.log("预付200定金并且已支付，得到50元优惠券")
                } else { //定金未支付，降到普通购买
                    if (stock > 0) {
                        console.log("普通购买，无优惠券")
                    } else {
                        console.log("库存不足");
                    }
                }
            }
            if (orderType === 3) {
                if (stock > 0) {
                    console.log("普通购买，无优惠券")
                } else {
                    console.log("库存不足");
                }
            }
        }
        //重构
        var order500 = function(orderType, pay, stock){
            if(orderType ===1 && pay){
                console.log("预付500定金并且已支付，得到100元优惠券")
            }else{
                order200(orderType, pay, stock)
            }
        }
        var order500 = function(orderType, pay, stock){
            if(orderType ===1 && pay){
                console.log("预付500定金并且已支付，得到100元优惠券")
            }else{
                order200(orderType, pay, stock)
            }
        }
        var order200 = function(orderType, pay, stock){
            if(orderType ===2 && pay){
                console.log("预付200定金并且已支付，得到50元优惠券")
            }else{
                orderNormal(orderType, pay, stock)
            }
        }
        var orderNormal = function(orderType, pay, stock){
            if (stock > 0) {
                    console.log("普通购买，无优惠券")
                } else {
                    console.log("库存不足");
                }
        }