函数是javascript对象属性的有效键吗？ [英] Are functions valid keys for javascript object properties?

问题描述

我想在javascript对象中使用函数作为键。以下工作至少在Chrome中有效：

I'd like to use functions as keys in a javascript object. The following works, at least in Chrome:

var registry = {};
function Foo(){  };
function Bar(){  };
registry[Foo] = 42;
registry[Bar] = 43;
alert(registry[Foo] + " < " + registry[Bar]);

标准涵盖了这个吗？它支持哪些浏览器？

Is this covered by the standard? By which browsers is it supported?

推荐答案

您放在方括号之间的所有内容都会转换为字符串，即使您发生这种情况也会发生放一个函数，一个日期，一个正则表达式......那么，你实际上是在创建一个这样的对象：

Everything you put between square brackets is converted into a string, and this happens even if you put a function, a date, a regexp... So there, you're actually creating an object like this:

var registry = {
    "function Foo(){  }" : 42,
    "function Bar(){  }" : 43
};

这是一种默认行为，如果你想知道它也适用于IE。它实际上是由John Resig在他的着名的 addEvent 功能。

This is a default behaviour, it works in IE too if you were wondering. It was actually exploited by John Resig in his famous addEvent function.

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