原型链

思维导图

1. 原型链中最终的构造器函数是function Function(),
2. 原型链中最终的原型是Object prototype

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1. new Foo()

function Foo() {};
var foo = new Foo();

Foo.prototype.constructor === Foo//output:true
foo.constructor === Foo //output:true
foo.__proto__ === Foo.prototype //output:true
foo.__proto__.constructor === Foo //output:true

例子
Foo.prototype.label = "crli";
foo.label === "crli"; //output: true
Foo.label === undefined; //output: true

function Foo() {};
var foo = new Foo();

例子
Foo.__proto__.xx = "aa";
Foo.__proto__ === Function.prototype//output: true
Foo.xx === aa; //output: true
foo.xx === undefined;//output: true

Function.prototype.__proto__ === Object.prototype

1. new Object()

var foo = new Object();
foo.__proto__ === Object.prototype //output:true
Object.prototype.__proto__ === null //output:true