自调函数的括号符号是否有助于Javascript的目的？ [英] Does parenthetical notation for self-invoked functions serve a purpose in Javascript?

问题描述

 （function（）{} {}当我在Javascript中看到自引用的匿名函数的例子时，我感到困惑。 return val;}）（）; 
  

这个语法和下面的语法有什么不同：

  function（）{return val;}（）; 
  

如果有人能给我一个具体的区别，这将有助于解决一直困扰着我的问题长久以来...

解决方案

Javascript没有块范围，所以这是一种创建临时局部范围的方法这不会污染全局名称空间。括号有两个作用：

1. 如果缺少某些javascript实现，它们会被翻转。


2. 它向读者表明与正常的函数声明不同的东西正在发生。所以作为一个约定，它表明这个函数被用作范围。
   

请看这里：
http://peter.michaux.ca/articles/an-important-pair-of -parens

I get confused when I see examples of self invoked anonymous functions in Javascript such as this:

(function () { return val;}) ();

Is there a difference between this syntax and the following:

function() { return val;} ();

If someone can give me a concrete difference, it would help put to rest a question that's been bugging me for ages...

解决方案

Javascript doesn't have a block scope, so this is a way to create a temporary local scope that doesn't pollute the global namespace. The parentheses serve two purposes:

1. Some implementations of javascript flip out if they're missing.
2. It signals to readers that something different from a normal function declaration is going on. So as a convention, it signals that this function is being used as a scope.

see here: http://peter.michaux.ca/articles/an-important-pair-of-parens

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