[JavaScript基础]学习②⑦--class继承

function Student(name) {
    this.name = name;
}

Student.prototype.hello = function () {
    alert('Hello, ' + this.name + '!');
}

用class

class Student {
    constructor(name) {
        this.name = name;
    }

    hello() {
        alert('Hello, ' + this.name + '!');
    }
}

class继承

class PrimaryStudent extends Student {
    constructor(name, grade) {
        super(name); // 记得用super调用父类的构造方法!
        this.grade = grade;
    }

    myGrade() {
        alert('I am at grade ' + this.grade);
    }
}

需要通过super(name)来调用父类的构造函数，否则父类的name属性无法正常初始化

不是所有的主流浏览器都支持ES6的class。可以试试Babel这个工具。

练习

'use strict';

class Animal {
    constructor(name) {
        this.name = name;
    }
}  

class Cat extends Animal{
  constructor(name){
   super(name);

   }
   
   say(){
      return 'Hello, '+this.name+'!';
   }
}

// 测试:
var kitty = new Cat('Kitty');
var doraemon = new Cat('哆啦A梦');
if ((new Cat('x') instanceof Animal) && kitty && kitty.name === 'Kitty' && kitty.say && typeof kitty.say === 'function' && kitty.say() === 'Hello, Kitty!' && kitty.say === doraemon.say) {
    alert('测试通过!');
} else {
    alert('测试失败!');
}