javascript 为什么 Chrome Dev Tool 将日期 __proto__ 显示为无效日期？
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Why does Chrome Dev Tool show a dates __proto__ as Invalid Date?
提问by Shane Courtrille
I know __proto__is deprecated (or not part of the standard) and all that but I'm still curious as to what it means when it says Invalid Date when I look at the __proto__value of..
我知道__proto__不推荐使用（或不是标准的一部分）等等，但我仍然很好奇当我查看__proto__..
var myDate = new Date(1331869050000);
采纳答案by Shane Courtrille
"I'm still curious as to what it means when it says Invalid Date"
“我仍然很好奇它说无效日期是什么意思”
That's simply the toStringvalue of the prototypeobject of the Dateconstructor function.
这只是构造函数toString的prototype对象的值Date。
Date.prototype.toString(); // "Invalid Date"
You can override it if you like...
如果你愿意，你可以覆盖它......
Date.prototype.toString = function() { return "I like turtles." };
var myDate = new Date(1331869050000);
myDate.__proto__; // I like turtles.
A little off topic, but __proto__is in the current working draft for the next version of ECMAScript, codename Harmony.
有点离题，但__proto__在 ECMAScript 下一个版本（代号 Harmony）的当前工作草案中。
http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts
http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts
- Added section B.3.1 with specifies
__proto__feature.
- 添加了 B.3.1 节并指定了
__proto__功能。
回答by Ben Sewards
considering you made a new Date object, I wouldn't worry about it. The reason being, if you try this code:
考虑到您创建了一个新的 Date 对象，我不会担心。原因是，如果您尝试此代码：
var myDate = new Date(1331869050000);
alert(typeof myDate.getMonth != 'undefined') //true
This will determine that you are inheriting the Date objects methods and that in fact, Date IS defined.
这将确定您正在继承 Date 对象方法，并且实际上已定义 Date。
If you would like further investigation, take a look at thispost.
如果你想进一步调查，看看这篇文章。
回答by dmvianna
The prototype of a Date instance has no defined value. Only the instance has a value. You define it when you instantiate it.
Date 实例的原型没有定义的值。只有实例才有值。在实例化它时定义它。
