javascript 原型继承 与class extends 继承对比

 

//父类 Animal
function Animal (name) {
    this.name = name;
    this.sleep = function () {
        console.log(this.name + '正在睡觉！')
    }
}

//cat 是 Animal 的子类
function Cat (name, age) {
    Animal.call(this, name);
    //子类 Cat 新增加的 成员 age eat()
    Cat.prototype.age = age;
    Cat.prototype.eat = function () {
        console.log(this.name + 'is cat ' + '正在吃东西' + ' my age is ' + this.age)
    }
}


//---------调用代码---------------------
var animal_obj = new Animal('动物');
animal_obj.sleep();

var cat_obj = new Cat('猫', 10);
cat_obj.sleep();
cat_obj.eat();



//-------------------------------------------------------class------------------------------------------------------------------
//父类 Animal
class Animal {
    constructor(name) {
        this.name = name;
    }
    sleep () {
        console.log(this.name + '正在睡觉！')
    }
}


//cat 是 Animal 的子类
class Cat extends Animal {
    //构造函数
    constructor(name, age) {
        super(name); //super 选调用父类构造方法
        this.age = age; //子类新增属性成员 age
    }
    //子类新增属性成员 eat(), class定义的成员函数不须要用 this.,也不用 function
    eat () {
        console.log(this.name + 'is cat ' + '正在吃东西' + ' my age is ' + this.age)
    }
}

//---------调用代码---------------------
var animal_obj = new Animal('动物');
animal_obj.sleep();

var cat_obj = new Cat('猫', 10);
cat_obj.sleep();
cat_obj.eat();
//-------运行结果一模一样--------------------------