构造函数原型内存图-实现继承

GO ={NumberWindowPerson: 0x100Student: 0x500stu: 0x800p: 0x900}

0x600: Student.prototype.__proto__

0x300: Person.prototype.__proto__

0x400: eating

函数

function() {    log(this.name + ' studying')}

key

value

__proto__

0x600  0x900

...

内存

0x500: Student

原型链实现继承

scope-chain

GO

Prototype

0x200

代码块

function() {    log(this.name + ' eating')}

function Person() {    this.name = 'tom'}Person.prototype.eating = function() {    log(this.name + ' eating')}function Student() {    this.sno = 111}var p = new Person()Student.prototype = pStudent.prototype.studying = function() {     log(this.name + ' studying')}var stu = new Student()

0x900: new Person的对象

ECS

0x100: Person

0x101: studying

0x600 0x900

0x101

null

constructor

0x500

0x600

studying

0x700

GEC

VO: GO       this

执行：new Student()          stu = new Student()

ox100

0x300

eating

0x400

FEC: Student AO

VO: GO+scope       this

执行：  1.构造函数St内部创建一个临时对象obj  2.obj.__proto__ = St.prototype  3.St内部this 绑定到obj  4.执行St内部代码  5.返回obj: ox800----AO出栈

0x600: Student.prototype的值

(临时对象obj)-0x800

0x200: Person.prototype

0x400: studying

Person构造this

指向这里的对象

name

tom