Javascript - 自执行函数：如果我可以使用非自执行函数创建本地作用域，为什么要使用它们？ [英] Javascript - self-executing functions : why to use them if I can create local scope with not self-executing functions?

问题描述

我知道这里和其他地方有很多关于自我执行功能的帖子，但在阅读帖子后我还有一些问题。

I know there are a lot of posts here and elsewhere about selfexecuting functions but I still have some questions after reading posts.

1. <为什么我会为变量分配一个自执行函数？如果看起来他们仍然执行自己。

1. why would I ever assign a self-executing function to a variable? If seems that they execute themselves anyways.

var myFunc=(function() {
 console.log('Hello World');
})();

我读了很多，使用自执行函数的原因是保持变量私有。如果我有一个不自动执行的功能，我在该功能中定义的所有东西都会是私有的吗？！

I read a lot that the reason to use self-executing functions is to keep variables private. If I have a not self-executing function, everything I define inside that function is gonna be private anyways?!

(function() {
 var name="my Name"
 console.log(name);
})();

vs.

 function() {
 var name="my Name"
 console.log(name);
 };
 //its the same

所以我不太明白自动执行函数如何保持局部范围（因为你可以使用非自动执行的函数），所以我看到的唯一原因是当你想自动执行时，例如在页面加载时使用它们。

So I dont quite understand how self-executing functions are to keep local scope (as you can do that using not self-executing functions) so the only reason I see is to use them when you want to execute automatically for example on page load.

谢谢！

还有一个问题：

var test=(function myFunc(){
      var name="Hello World"
      return {
        test1: function(){
          return name;
        },
        test2:function(){
          return name+"1"
        }
      }
    })()

    test.test1()

vs

    var test=function myFunc(){
      var name="Hello World"
      return {
        test1: function(){
          return name;
        },
        test2:function(){
          return name+"1"
        }
      }
    }

    test.test1()

- >这里究竟发生了什么因为IIFE我实际上可以执行test.test1 （）而不是常规函数？

--> what exactly happens here that because of IIFE I can actually execute test.test1() and not with a regular function?

推荐答案

当你想保留你的范围时，你通常会将你的函数包装在一个匿名函数中遏制。这也是模块模式的一部分，它仍然非常流行：

You usually wrap your functions in a anonymous function when you want to keep your scope contained. This is also part of the module pattern which is still pretty popular:

https://toddmotto.com/mastering-the-module-pattern/

然后你可以分配结果 IIFE 变量，因此您的范围只能是通过调用该变量来访问。

Then you can assign the outcome of that IIFE to a variable so your scope can only be accessed by calling that variable.

myScope.myLocallyScopedProperty or myScope[myLocallyScopedProperty]

您的其他功能需要手动调用，也可以从任何地方访问。

Your other function needs to be called manually and it also accessible from anywhere.

我建议阅读Todd Moto的文章解释了很多。

I suggest reading the article by Todd Moto it explains a lot.

这篇关于Javascript - 自执行函数：如果我可以使用非自执行函数创建本地作用域，为什么要使用它们？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！