在 jQuery 中为每个循环嵌套嵌套的 $(this)
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Targeting $(this) within nested for each loops in jQuery
提问by mmmoustache
I'm trying to figure out, when iterating through some list items, how to target each "$(this)" equivalent within nested foreach loops. Here is an example of my problem:
我试图弄清楚，在迭代某些列表项时，如何在嵌套的 foreach 循环中定位每个“$(this)”等价物。这是我的问题的一个例子：
$('li').each(function(){
// I believe $(this) would target each li item...
$(this).children("li").each(function(){
// ... but how can I target each of these li items? Doesn't $(this) target the original loop?
});
});
回答by Gabe
$('li').each(function(){
var $this = $(this);
$this.children("li").each(function(){
$this; // parent li
this; // child li
});
});
回答by mmmoustache
Don't use this! Use function parameters!
不要用this！使用函数参数！
$('li').each(function(i, li){
$(li).children("li").each(function(ii, li2){
$(li)...
$(li2)...
});
});
This is more in keeping with the native JavaScript iterators.
这更符合原生 JavaScript 迭代器。
...though an <li>can't be the direct child of another <li>
...虽然<li>不能是另一个的直接孩子<li>
回答by Elias Van Ootegem
Look at the basic "prototypes" of jQuery functions (or methods, if you will):
查看 jQuery 函数（或方法，如果您愿意）的基本“原型”：
$[jQobject].[func]([callback]);
The callback is the function that will be invoked in the context of the jQ object. The context being this, obviously. Put simply that means that:
回调是将在 jQ 对象的上下文中调用的函数。this显然，上下文是。简单地说就是：
$('#foo').click(function(){});
/\ /\
|| Is the context ||
=====================
The same applies to your case, regardless of the loops being nested or not:
这同样适用于您的情况，无论循环是否嵌套：
$('ul').each(function()
{
//this is ul
var that = this;//you'll often see code like this
$('li', this).each(function()
{
//this is li
//that is parent ul
});
});
回答by SLaks
but how can I target each of these li items? Doesn't $(this) target the original loop?
但是我怎样才能针对这些 li 项目中的每一个呢？$(this) 不是针对原始循环吗？
Nope.
不。
thiscomes from the function you're directlyin.
this来自您直接进入的函数。
回答by Blender
Nope, thisrefers to each of the child <li>items. Try it out.
不，this是指每个子<li>项。试试看。
Most (if not all) DOM-interacting jQuery callbacks set thisto to the DOM element that you're working with.
大多数（如果不是全部）DOM 交互 jQuery 回调设置this为您正在使用的 DOM 元素。
You could also write:
你也可以这样写：
$('li').children("li").each(function(){
var $this = $(this);
});
