子类重写了父类的方法为什么还是会报错
冖儿
2017-07-11 10:48
var Beverage = function(){}
Beverage.prototype.boilWater = function(){
console.log("煮沸水");
};
Beverage.prototype.brew = function(){
// console.log("冲泡饮料");
throw new Error("子类必须重写该方法");
};
Beverage.prototype.putInCup = function(){
// console.log("倒进杯中");
throw new Error("子类必须重写该方法");
};
Beverage.prototype.addCondiments = function(){
// console.log("添加辅料");
throw new Error("子类必须重写该方法");
};
Beverage.prototype.customIsWant = function(){
// 演示钩子方法
return true;
}
Beverage.prototype.init = function(){
this.boilWater();
this.brew();
this.putInCup();
if(this.customIsWant()){
this.addCondiments();
}
}
var Coffee = function(){}
Coffee.prototype.brew = function () {
console.log("用开水冲泡咖啡");
}
Coffee.prototype.putInCup= function () {
console.log("把咖啡倒进杯子里");
}
Coffee.prototype.addCondiments= function () {
console.log("加糖和牛奶");
}
Coffee.prototype.customIsWant = function(){
return false;
}
var Tea = function(){}
Tea.prototype.brew = function () {
console.log("用开水冲泡茶");
}
Tea.prototype.putInCup= function () {
console.log("把茶倒进杯子里");
}
Tea.prototype.addCondiments= function () {
console.log("加柠檬");
}
Tea.prototype.customIsWant = function(){
return window.confirm("请问需要加柠檬吗？");
}
// js的继承
Coffee.prototype = new Beverage();
Tea.prototype = new Beverage();
var coffee = new Coffee();
console.log(coffee.brew());
coffee.init();
var tea = new Tea();
tea.init();3回答
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- 好孩子100分
- 2019-09-29 15:29:08
老师的代码有问题
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 Tea = function() {};
Tea.prototype = new Beverage();
Tea.prototype.boilWater = function() {
console.log("把水煮沸");
};
Tea.prototype.brew = function() {
console.log("用沸水冲泡茶叶");
};
Tea.prototype.pourInCup = function() {
console.log("把咖啡倒进杯子");
};
Tea.prototype.addCondiments = function() {
console.log("加柠檬");
};
Tea.prototype.customerWantsCondiments = function() {
return window.confirm("请问是否需要添加调料");
};
var Coffee = function() {};
Coffee.prototype = new 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 = new Tea();
tea.init();
var coffee = new Coffee();
coffee.init();
-
- 一飞同学
- 2017-09-19 14:35:27
继承也可以写成 Coffee.prototype = Object.create(Beverage.prototype);
Object.create()创建一个空对象，这个空对象的原型指向Beverage.prototype,将Coffee的prototype=这个空对象的原型，实现一个继承关系，
-
- 慕粉3777950
- 2017-07-14 18:24:01
代码顺序问题，应该先实现继承，然后再扩写子类的方法。你的代码中先扩写了原型对象的方法，然后再写继承Coffee.prototype = new Beverage(); 这样的话之前写的方法就被覆盖了，所以重写并没有实现
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