Javascript的"Object.getOwnPropertyNames"缺少属性？

Question

我喜欢Object.getOwnPropertyNames方法.它似乎是一个从JS shell中学习对象的有用工具.

然而,令我疯狂的是,getOwnPropertyNames似乎缺少一些(注意:在我的测试中,我运行的是ECMA 5实现 - 谷歌Chrome版本28.0.1500.95).

这是一个例子:

> var x= []
undefined
> x.constructor
function Array() { [native code] }
> Object.getOwnPropertyNames(x)
["length"]

很明显,x有很多属性!(例如https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/prototype)

> x.push
function push() { [native code] }
> x.pop
function pop() { [native code] }

谁能帮忙解释一下这里发生了什么？谢谢!:d

编辑:好的!我看到getOwnPropertyNames只获取手头对象的属性名称.有没有一种简单的方法来获得继承属性？或者也许唯一的方法是遍历object.constructor.prototype .__ proto__？

Answer 1

根据https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto

该__proto__属性已弃用，不应使用。Object.getPrototypeOf应该使用代替__proto__getter 来确定对象的 [[Prototype]]。

> x = [];
[]
> Object.getOwnPropertyNames(Object.getPrototypeOf(x));
["length", "constructor", "toString", "toLocaleString", "join", "pop", "push", "concat",
 "reverse", "shift", "unshift", "slice", "splice", "sort", "filter", "forEach", "some", 
 "every", "map", "indexOf", "lastIndexOf", "reduce", "reduceRight"]

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getPrototypeOf