var $ this = this的原因是什么？ [英] What is the reason for var $this = this

问题描述

我不是最好的jquery，我遇到了一个var初始化，我不知道编写代码的人为什么会这样做。

I'm not the best at jquery and I came across a var initialization that I don't know why the person who wrote the code did it this way.

在插件的init中，我们有

In the init for a plugin, we have

this.init = function(settings) {
    var $this = this;
    this.s = {
        initialSlide: 0,
        firstSlide: true,
    };
   ... more code, some uses $this, some uses "this"
}

那么$ this和this之间有什么区别？为什么不一直使用一个或另一个？

So what is the difference here between "$this" and "this" and why not use one or the other all the time?

推荐答案

通常，这意味着此的副本。关于这个的事情是它在每个函数中都会发生变化。但是，以这种方式存储会使 $ this 保持不变，而此确实会发生变化。

Generally, this means a copy of this. The thing about this is that it changes within each function. Storing it this way, however, keeps $this from changing whereas this does change.

jQuery大量使用魔法这个值。

jQuery heavily uses the magic this value.

考虑这段代码，你在哪里可能需要你看到的东西：

Consider this code, where you might need something like you are seeing:

$.fn.doSomethingWithElements = function() {
    var $this = this;

    this.each(function() {
        // `this` refers to each element and differs each time this function
        //    is called
        //
        // `$this` refers to old `this`, i.e. the set of elements, and will be
        //    the same each time this function is called
    });
};

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