### ES5 中的继承 ```js function User(name, age){ this.name = name; this.age = age; } function VipUser(name, age, level){ // User.call(this, name, age); User.apply(this, [name, age]); this.level = level; } var xu = new VipUser('xu', 23, 13); // 在VipUser 原型上定义一个say方法 VipUser.prototype.say = function() { console.log(this.name); } console.log(xu); xu.say(); ``` 输出：  ### ES6 中的继承 ```js function User(name, age){ this.name = name; this.age = age; } class VipUser extends User { constructor(name, age, level) { super(name, age); this.level = level; } say() { console.log(this.name); } } var xu = new VipUser('xu', 23, 12); console.log(xu); xu.say(); ```