JS 中的继承

原生JS（ES5）中的继承

对象冒充继承: 没法继承原型链上面的属性和方法

function Person(name, age) {
    this.name = name;
    this.age = age;
    this.run = function () {
        console.log(`${this.name} is ${this.age}岁`)
    }
}
Person.prototype.sex = '男'
Person.prototype.work = function () {
    console.log(`${this.name} is ${this.sex} and ${this.age}岁`)
}

function Man(name, age) {
    Person.call(this, name, age) //对象冒充实现继承
}

var man = new Man('sally', 18)
man.run()
man.work()

/**
  man.work is not a function
*/

　　

原型链继承：可以继承构造函数里面以及原型链上面的属性和方法，实例化子类的时候没法给父类传参

function Person(name, age) {
    this.name = name;
    this.age = age;
    this.run = function () {
        console.log(`${this.name} is ${this.age}岁`)
    }
}
Person.prototype.sex = '男'
Person.prototype.work = function () {
    console.log(`${this.name} is ${this.sex} and ${this.age}岁`)
}


//原型链继承
function Man(name, age) {}
  
Man.prototype = new Person() 

var man = new Man('sally', 18)
man.run()
man.work()

/**
  undefined is undefined岁
  undefined is 男 and undefined岁
*/

　　

采用原型链继承和对象冒充继承相结合的方式继承：

function Person(name, age) {
    this.name = name;
    this.age = age;
    this.run = function () {
        console.log(`${this.name} is ${this.age}岁`)
    }
}
Person.prototype.sex = '男'
Person.prototype.work = function () {
    console.log(`${this.name} is ${this.sex} and ${this.age}岁`)
}

//对象冒充实现继承
function Man(name, age) {
    Person.call(this, name, age) 
}
//原型链继承
Man.prototype = new Person() 

var man = new Man('sally', 18)
man.run()
man.work()


/**
 * sally is 18岁
 * sally is 男 and 18岁
 */

　　

ES6 中的继承

通过 extends 关键字：

class Person {
    constructor(name, age) {
        this.name = name;
        this.age = age;
    }
    getInfo() {
        console.log(`姓名:${this.name} 年龄:${this.age}`);
    }
    run() {
        console.log('run')
    }
}
class Man extends Person {  //继承了Person  extends  super(name,age);
    constructor(name, age, sex) {
        super(name, age);   //实例化子类的时候把子类的数据传给父类
        this.sex = sex;
    }
    print() {
        console.log(this.sex);
    }
}
var man = new Man('jack', '30', '男');
man.getInfo();

/**
 * 姓名:jack 年龄:30
 */