将jquery函数包装在闭包中有什么好处? [英] What is the benefit of wrapping a jquery function in a closure?

问题描述

您好，我一直在尝试将我对JQuery的知识提高到一个新的水平，到目前为止，我认为我已经理解了所有内容，但是当我尝试使用更高级的教程时，我注意到JQuery例程的几个实例被包裹在一个闭包中(见下文)，但是，令我困惑的是它传递了一个$并返回了JQuery.我的问题是为什么?返回的JQuery我该怎么办?

Hi I've been busy trying to take my knowledge of JQuery to the next level, So far I think I've understood everything but as I've ventured onto more advanced tutorials I've noticed several instances where the JQuery routine is wrapped in a closure (see below) however, the thing that confuses me is that it passes a $ and returns JQuery. My question is why? what can I do with the returned JQuery?

我真的很感谢人们能为我提供的启发.

I'd really appreciate any light that people can shed on this for me.

(function($){
  $(document).ready(function(){
    var arr = $.map($("LI"), function(item, index){
      while (index < 3)
      {
        return $(item).html();
      }
      return null;
    });
    $(document.body).append("<span>The first three authors are: " +
      arr.join(", ") + "</span>");
  });
})(jQuery);

谢谢.

Rob

推荐答案

这是一个自我调用的匿名函数(已声明并立即执行的未命名函数)，它带有一个分配给参数$的参数.传递给该参数的值为jQuery函数jQuery.

It's a self invoking anonymous function (an un-named function that is declared and immediately executed) that takes one argument that gets assigned to the parameter $. The value passed in for the argument is jQuery, the jQuery function.

这样做是为了使速记$可以在函数范围内用于表示jQuery.由于该函数内部的所有代码都在该函数的范围内，因此这是一种很好的模式，可以自我包含代码并且不污染全局名称空间.

This is done so that the shorthand $ can be used inside the scope of the function to mean jQuery. Since all of the code inside of the function is in the scope of the function, it's a nice pattern for self containing the code and not polluting the global namespace.

这也是允许您在函数内使用jQuery的$速记的一种不错的模式-可能会为$速记(window.$)分配其他内容，如果您在一页上使用多个库.通过使用模式，您仍然可以使用$引用函数中的jQuery对象以使其更加熟悉和简洁.

It's also a nice pattern for allowing you to use the $ shorthand for jQuery inside of the function - it could be the case that the $ shorthand (window.$) is assigned something else, as can happen if you use multiple libraries on one page. By using the pattern, you can still use $ to reference jQuery object in the function for familiarity and terseness.

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