js原型链演示02-1-new 原理

函数Object()

Object.prototype

Foo.prototype

Null

对象｛a:12｝

原型对象Object { }

原型对象Foo { }

__proto__

var foo = new Foo(12)

function Foo(a){this.a = a;}

new Foo() 的理解1:function Foo(a){// var this = {};// this.__proto__ = Foo.prototype;// this.constructor = this.__proto__ .constructor;this.a = a;// return this;}

constructor

函数Foo(a)