JavaScript中的__proto__、[[prototype]]和prototype

目录

• 1. 前言
• 2. prototype相关介绍
• 3. __proto__与[[prototype]]相关介绍
• 4. 一张图分析三者的关系
• 5. 一系列案例分析

前言

　　proto、[[prototype]]和prototype三个概念及相关内容是javascript比较复杂且容易混淆的内容。本文尝试进行总结和分析。

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prototype相关介绍

　　待续。

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__proto__与[[prototype]]相关介绍

　　待续。

一张图分析三者的关系

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一系列案例分析

function Foo(){
  console.log(1);
}
var a = new Foo();
console.log(a.prototype === Foo.prototype);       //false

function Foo(){
  console.log(1);
}
var a = new Foo();
console.log(a.__proto__ === Foo.prototype);       //true

function Foo(){
  console.log(1);
}
var a = new Foo();
console.log(a.prototype);       //undefined

function Foo(){
  console.log(1);
}
var a = new Foo();
console.log(a.__proto__);       //object{}

function Foo(){
  console.log(1);
}
Foo.prototype = { };
var a = new Foo();
console.log(a.constructor === Foo);       //false

function Foo(){
  console.log(1);
}
Foo.prototype = { };
var a = new Foo();
console.log(a.constructor === Object);        //true

function Foo(){
  console.log(1);
}
Foo.prototype = { };
var a = new Foo();
console.log(a.constructor);

function Foo(){
  console.log(1);
}
Foo.prototype = { };
var a = new Foo();
console.log(a.__proto__);       //function Object() { [native code] }

function Foo(){
  console.log(1);
}
Foo.prototype = { };
var a = new Foo();
console.log(a.__proto__.__proto__ === Object.prototype);        //true

function Foo(){
  console.log(1);
}
var a = new Foo();
console.log(a.__proto__ === a.prototype);       //false

var a = new Function();
console.log(a.__proto__ === Function.prototype);        //true

function Foo(){
  console.log(1);
}
var a = new Foo();
console.log(a.constructor.prototype === a.__proto__);        //true

function Foo(){
  console.log(1);
}
var a = new Foo();
console.log(a.constructor.prototype === Foo.prototype);        //true