绑定到`undefined`而不是`null`有什么好处 [英] what's the benefit of binding to `undefined` instead of `null`

问题描述

我经常看到，当一个函数需要在没有特定上下文的情况下使用绑定参数调用时， undefined 通常比 null 作为上下文的选择，如：

I often see that when a function needs to be called with bound parameters in no particular context the undefined is more often than not is preferred over the null as a choice of context, as in:

f.call(undefined, param1, param2)

优先于：

f.call(null, param1, param2)

我'我想知道是否有任何特殊原因？

I'm wondering if there is any particular reason for this?

推荐答案

绑定到<的好处是什么？ code> undefined 而不是 null ？

我认为没有。来自 10.4.3输入功能代码：

1. 如果功能代码是严格代码，设置 ThisBinding 到 thisArg 。


2. 否则如果 thisArg null 或 undefined ，设置 ThisBinding 到全局对象。


3. ...

1. If the function code is strict code, set the ThisBinding to thisArg.
2. Else if thisArg is null or undefined, set the ThisBinding to the global object.
3. ...

所以，如果代码并不严格，在这两种情况下这个都将被设置为全局对象。

So, if the code is not strict, in both cases this will be set to the global object.

但如果代码是严格的，此实际上将是 null 或 undefined 。可以实现 f 来区分这些情况，但这对我来说似乎不太可能。

But if the code is strict, this will actually either be null or undefined. f could be implemented to distinguish these cases, but that doesn't seem to be a very likely scenario to me.

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