概念

1.原型對(duì)象(prototype) 只有函數(shù)有原型對(duì)象 相當(dāng)于每個(gè)函數(shù)具有一個(gè)prototype屬性忽媒，所指向的對(duì)象争拐，就叫原型對(duì)象
2.原型鏈由對(duì)象的proto 繼承連接下來，對(duì)象的proto指向其構(gòu)造函數(shù)的原型對(duì)象晦雨，其中對(duì)象包括普通對(duì)象和函數(shù)對(duì)象

實(shí)例詳解

    function Car() {
        
    }
    var car = new Car();

    console.log(car.__proto__ === Car.prototype);//car 是非函數(shù)對(duì)象 只有__proto__屬性
    console.log(car.__proto__.__proto__  === Object.prototype)//car.__proto__.__proto__ = Car.prototype.__proto__ = Object.prototype
    console.log(car.__proto__.prototype)  //undefined
    //總結(jié)的普通對(duì)象的__proto__最終都指向Object.prototype,普通對(duì)象沒有prototype

    console.log(Car.prototype)//   {constructor:function(){ }}
    console.log(Car.prototype.prototype)//undefined
    console.log(Car.prototype.__proto__ === Object.prototype)//Object.prototype
    console.log(Car.__proto__ ===Function.prototype)//
    console.log(Car.__proto__.__proto__)

    //所有函數(shù)對(duì)象都有原型對(duì)象   所有函數(shù)對(duì)象的(一級(jí))__proto__指向Function.prototype(空函數(shù)) 最終指向Object.prototype

    console.log(Function.prototype === Function.__proto__);//true
    console.log(Function.prototype === Object.__proto__)//true

總結(jié)

所有普通對(duì)象的的最終proto 都指向Object.prototype
所有函數(shù)對(duì)象的一級(jí)proto 都指向Function.prototype(空函數(shù)) 最終proto還是指向Object.prototype
所有函數(shù)對(duì)象都有prototype架曹，他們的原型對(duì)象proto最終都指向Object.proto,沒有prototype對(duì)象，原型對(duì)象都有constructor屬性 指向構(gòu)造函數(shù)本身闹瞧。函數(shù)對(duì)象包括 Function Object,Array绑雄，Date等函數(shù)。

繼承

ES5

    function Person(name){
        this.name = name;
    }
    Person.prototype.getName = function(){
        console.log(this.name);
    }

    function Student(name){
        Person.call(this,name);
    }
    var __proto = Object.create(Person.prototype);
    __proto.constructor = Student;
    Student.prototype = __proto;
    Student.prototype.getAge = function(){
        console.log("我是學(xué)生")
    }
var stu  = new Student("li")
stu.getName();

ES6

class Person{
    constructor(name){
        this.name = name;
    }
    getName(){
        console.log(this.name)
    }
}

class Student extends Person{
    constructor(name){
        super(name);
    }
    getName(){
        super.getName();
    }
}
const stu  = new Student("li")
stu.getName();