这种自调用匿名函数变体背后的原因

问题描述

在查看 github 上的 code 时，我发现了以下内容:

While looking at code on github, I found the following:

(function() {

}).call(this);

这显然是一个自调用匿名函数.但是为什么会这样写呢?我习惯于看到规范的变体 (function() {})().

This is clearly a self invoking anonymous function. But why is it written this way? I'm used to seeing the canonical variant (function() {})().

将 .call(this) 用于自调用匿名函数有什么特别的优势吗?

Is there any particular advantage to using .call(this) for a self invoking anonymous function?

看起来一些 commonjs 环境将 this 设置为模块顶层的非全局值.哪些，以及他们将 this 设置为您可能想要保留的内容?

It looks like some commonjs environments set this to a non-global value at the top level of a module. Which ones, and what do they set this to that you might want to preserve?

推荐答案

.call(this) (实际上只是 () 直到我改变它)确保你的顶级级别 this 通过严格模式保持一致，--bare 选项和/或运行环境(顶级 this 不指向全局对象).

.call(this) (was actually just () until I changed it) ensures your top level this to be consistent through strict mode, --bare option and/or the running environment (where top level this doesn't point to global object).

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