JavaScript中的原型链

+ constructor

+ prototype

一、函数有3种形式，2种用途# 形式1，函数声明，用途1：函数调用，比如foo1()function foo1(){}# 形式2，函数表达式，使用箭头函数，用途1：函数调用，比如foo2()var foo2 = ()=>{}# 形式3，函数表达式，使用正常函数，用途1：函数调用，比如foo3()var foo3 = function(){}# 用途2：当构造函数，比如前面的var student3 = new Student(\"小红\

由【xx.protype】指向【xx.protype对象】的“原型对象链”

Student.prototype.__proto__ === Object.prototype

Object.prototype.constructor === Object即student1-3constructor === Object

typeof: 'function'Function

typeof: 'object'foo3 {}即是foo3.prototype

+ __proto__

Array.prototype.__proto__ === Object.prototype

+ other attrs

typeof: 'object'arr1

arr1.__proto__ === Array.prototype

foo1.prototype.__proto__ === Object.prototype

typeof: 'function'Student

foo1.constructor

Student.prototype === Student {}

对象的constructor属性用于返回创建该对象的函数，也就是我们常说的构造函数instance.constructor实际上是instance.__proto__.constructor，所以student1-2.constructor是Object，而student3.constructor是Student；

typeof: 'object'arr2

typeof: '实例类型'实例

undefined

typeof: 'function'foo2

foo3.prototype.__proto__ === Object.prototype

typeof: 'function'Function.prototype

+ consturctor

typeof: 'object'Student {}即是Student.prototype

typeof: 'function'Array

student2.__proto__ === Object.prototype

foo3.__proto__ === Function.prototype

Object.__proto__ === Function.prototype

arr3.__proto__ === Array.prototype

Function.prototype

Function.prototype.__proto__ === Object.prototype，形成了一个闭环

Function.prototype.constructor === Function说明Function创建了Function自己

Function.__proto__ === Function.prototype

Array.prototype.constructor

Student.__proto__ === Function.prototype

- 对象Object

+ other attrs    - name: '小明'    - age: 16

typeof: 'object'student1

由xx.prototype.constructor指向构造函数的构造链

一、对象有3种创建方式# 1. 使用{}直接定义对象var student1 = {    name: \"小明\

student3.__proto__ === Student.prototype

foo3.constructor

typeof: '基础对象/类型/函数的类型'基础对象/类型/函数，比如Object/Function/Array..

图例

typeof: 'object'[]即是Array.prototype

Object.prototype.__proto__ === null

Object.prototype === {}

typeof: 'function'Object

+ other attrs    - name: '小红'    - age: 18    - ShowInfo: [Function]

由instance.__proto__指向Base.prototype的“原型链”

+ other attrs    - name: '小军'    - age: 17

student1.__proto__ === Object.prototype

typeof: 'object'student2

null

foo1.__proto__ === Function.prototype

typeof: 'function'foo3

foo2.__proto__ === Function.prototype

typeof: 'function'foo1

- 构造函数Constructor

Array.__proto__ === Function.prototype

arr2.__proto__ === Array.prototype

- 函数Function

typeof: 'object'arr3

Stuent.prototype.constructor === Student本身

typeof: '原型对象类型'原型对象

typeof: 'object'foo1 {}即是foo1.prototype