为什么以及如何在javascript中使用IIFE [英] Why and how to use IIFE in javascript

问题描述

在此示例代码中：

    (function(){
           var obj = function() {

           };

           obj.prototype.hello = function(){
                 console.log('Hello World!');
           };
    })();

我看到很多图书馆这样做。为什么要将代码包装在立即调用函数表达式（IIFE）

I see a lot of libraries doing this. Why is wrapping your code in an Immediately Invoked Function Expression (IIFE) a good practice? And how do I access this object outside, like jquery does?

因为如果我这样做了：

   var test = new obj();

浏览器显示obj未定义。

The browser displays that obj is undefined.

推荐答案

避免污染外部范围。你确定没有任何变量会脱离它。
但是，您确实需要将其导出。从内部使用 window.obj = obj; （使其成为全局）或返回它：

To avoid polluting outer scope. You're sure no variables are going to "get out" of it. But yes, you do need to export it. Either using window.obj = obj; from inside (to make it global) or return it :

var obj = (function() {
  var obj = function() {};
  obj.prototype.sayHello = function() {}; 
  return obj;
})();

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