在IE8中使用javascript __proto__ [英] Using javascript __proto__ in IE8

问题描述

嗨我在javascript中有这两个对象

Hi I have this two objects in javascript

var john = { firstname: 'John', lastname: 'Smith' }

var jane = { firstname: 'Jane' }

这样做：

jane.__proto__ = john;

我可以访问jane的房产以及john的房产

I can access to jane's properties and also john's properties

如果IE8中不支持 __ proto __ ，那么相当于写这个：

If __proto__ is not supported in IE8 for example, what's the equivalent to write this:

jane.__proto__ = john;

谢谢！

推荐答案

IE中没有等效或标准的机制。 （ __ proto __ 属性是非标准扩展名，因为ECMAScript标准中未指定 。）

There is no equivalent or standard mechanism in IE. (The __proto__ property in Firefox is non-standard extension as is not specified in the ECMAScript standards.)

[[prototype]]对象只能通过在函数对象上设置 prototype 属性来指定 ，该对象充当构造函数之前构建一个新对象。然而，[[prototype]]可以稍后突变。

The [[prototype]] object can only be specified by setting the prototype property upon the function-object which acts as the constructor before the construction of a new object. The [[prototype]] can, however, be mutated later.

无论如何，这是指定[[原型]的一个小例子]来自现有的对象。请注意，[创建新对象之前完成。 ECMAScript第5版介绍 Object.create ，它可以执行以下操作>和浅层克隆一个对象。

Anyway, here is a little example of specifying a [[prototype]] from an existing object. Note that the [[prototype]] assignment must be done before the new object is created. ECMAScript 5th edition introduces Object.create which can do the following and shallow-clone an object.

function create (proto) {
    function f () {}
    f.prototype = proto
    return new f
}
var joe = create({})
var jane = create(joe)
joe.name = "joe"                   // modifies object used as jane's [[prototype]]
jane.constructor.prototype === joe // true
jane.__proto__ === joe             // true  -- in Firefox, but not IE
jane.name                          // "joe" -- through [[prototype]]
jane.constructor.prototype = {}    // does NOT re-assign jane's [[prototype]]
jane.name                          // "joe" -- see above

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