js中构造函数与原型

本文为阅读博文http://clarkdo.github.io/javascript/2014/08/21/17/后总结而得

①：

f1._proto_==Foo.prototype//true

②：

function Foo() { } ; var f1 = new Foo();Foo.prototype.x = "hello";f1.x   //=> helloFoo.x //=> undefined

注：所有对象会自动读取原型链的属性, 就像那些属性是对象自身定义的.若对象中定义了与原型链中重复的属性，则原型链上的属性会隐藏。

举个栗子：

function foo() { } f1 = new foo();f2 = new foo();foo.prototype.x = "hello";f1.x  => "hello"f2.x  => "hello";f1.x = "goodbye";   //setting f1.x hides foo.prototype.xf1.x  => "goodbye"  //hides "hello" for f1 onlyf2.x  => "hello"  delete f1.xf1.x  => "hello";   //foo.prototype.x is visible again to f1.