事件不会添加到 for 循环中 [英] Event doesn't get added in a for-loop

问题描述

这是html.如果单击链接，我想用一些文本替换它前面的跨度元素.

This is the html. If a link is clicked I want to replace the span-element in front of it with some text.

<p><span id="sp1">that1</span> <a href="#" id="update1">Update1</a></p>
<p><span id="sp2">that2</span> <a href="#" id="update2">Update2</a></p>
<p><span id="sp3">that3</span> <a href="#" id="update3">Update3</a></p>
<p><span id="sp4">that4</span> <a href="#" id="update4">Update4</a></p>
<p><span id="sp5">that5</span> <a href="#" id="update5">Update5</a></p>

如你所见，我的想法是给 spans en 锚点相同的 id 和一个数字.

As you can see, my idea was to give the spans en the anchors identical id's and a number.

在我的 jquery 代码中，我遍历所有的锚元素，给它们一个点击事件，导致它前面的跨度元素被替换.

In my jquery-code I loop through all the anchor-elements, give them a click-event that causes the span-element in front of it to be replaced.

<script type="text/javascript" >

  $(document).ready(function() {
   var numSpans = $("span").length;
   for (n=0;n<=numSpans;n++) {
     $("a#update" + n).click(function(e){
       $('span#sp' + n).replaceWith('this');
       e.preventDefault();
     });    
   }   
  });

</script>

由于某种原因，这不起作用.

For some reason this does not work.

我做错了什么?

推荐答案

原始代码的问题在于您正在对变量 n 创建闭包.当事件处理程序被调用时，它是在调用点而不是声明点使用 n 的值调用的.您可以通过添加警报呼叫来查看这一点:

The problem with your original code is that you're creating a closure on the variable n. When the event handler is called, it is called with the value of n at the point of invocation, not the point of declaration. You can see this by adding an alert call:

$(document).ready(function() {
    var numSpans = $("span").length;
    for (n = 1; n <= numSpans; n++) {
        $("a#update" + n).click(function(e) {
            alert(n); //Alerts '6'
            $('span#sp' + n).replaceWith('this');
            e.preventDefault();
        });
    }
})

解决此问题的一种方法是在每次迭代中对 n 的值创建一个闭包，如下所示:

One way to fix this is to create a closure on the value of n in each iteration, like so:

$(document).ready(function() {
    var numSpans = $("span").length;
    for (n = 1; n <= numSpans; n++) {
        $("a#update" + n).click(
            (function(k) {
                return function(e) {
                    alert(k);
                    $('span#sp' + k).replaceWith('this');
                    e.preventDefault();
                }
            })(n)
        );
    }
})

但是，这很麻烦，您最好使用更 jQuery-y 的方法.

However, this is messy, and you'd do better to use a more jQuery-y method.

执行此操作的一种方法是从您的代码中删除 id.除非您需要它们用于其他用途，否则它们不是必需的:

One way to do this would be to remove the ids from your code. Unless you need them for something else, they're not required:

<p><span>that1</span> <a href="#" class="update">Update1</a></p>
<p><span>that2</span> <a href="#" class="update">Update2</a></p>
<p><span>that3</span> <a href="#" class="update">Update3</a></p>
<p><span>that4</span> <a href="#" class="update">Update4</a></p>
<p><span>that5</span> <a href="#" class="update">Update5</a></p>

jQuery:

$(function() {
    $('a.update').live('click', function() {
        $(this).siblings('span').replaceWith("Updated that!");
    });
});

jsFiddle

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