如何在 INPUT 标签上没有 ID 属性的情况下使用 LABEL 标签的 FOR 属性
下面代码中说明的问题是否有解决方案?首先在浏览器中打开代码以直截了当，无需查看所有代码即可知道您要查找的内容.
Is there a solution to the problem illustrated in the code below? Start by opening the code in a browser to get straight to the point and not have to look through all that code before knowing what you're looking for.
<html>
<head>
<title>Input ID creates problems</title>
<style type="text/css">
#prologue, #summary { margin: 5em; }
</style>
</head>
<body>
<h1>Input ID creates a bug</h1>
<p id="prologue">
In this example, I make a list of checkboxes representing things which could appear in a book. If you want some in your book, you check them:
</p>
<form>
<ul>
<li>
<input type="checkbox" id="prologue" />
<label for="prologue">prologue</label>
</li>
<li>
<input type="checkbox" id="chapter" />
<label for="chapter">chapter</label>
</li>
<li>
<input type="checkbox" id="summary" />
<label for="summary">summary</label>
</li>
<li>
<input type="checkbox" id="etc" />
<label for="etc">etc</label>
<label>
</li>
</ul>
</form>
<p id="summary">
For each checkbox, I want to assign an ID so that clicking a label checks the corresponding checkbox. The problems occur when other elements in the page already use those IDs. In this case, a CSS declaration was made to add margins to the two paragraphs which IDs are "prologue" and "summary", but because of the IDs given to the checkboxes, the checkboxes named "prologue" and "summary" are also affected by this declaration. The following links simply call a javascript function which writes out the element whose id is <a href="javascript:alert(document.getElementById('prologue'));">prologue</a> and <a href="javascript:alert(document.getElementById('summary'));">summary</a>, respectively. In the first case (prologue), the script writes out [object HTMLParagraphElement], because the first element found with id "prologue" is a paragraph. But in the second case (summary), the script writes out [object HTMLInputElement] because the first element found with id "summary" is an input. In the case of another script, the consequences of this mix up could have been much more dramatic. Now try clicking on the label prologue in the list above. It does not check the checkbox as clicking on any other label. This is because it finds the paragraph whose ID is also "prologue" and tries to check that instead. By the way, if there were another checkbox whose id was "prologue", then clicking on the label would check the one which appears first in the code.
</p>
<p>
An easy fix for this would be to chose other IDs for the checkboxes, but this doesn't apply if these IDs are given dynamically, by a php script for example.
Another easy fix for this would be to write labels like this:
<pre>
<label><input type="checkbox" />prologue</label>
</pre>
and not need to give an ID to the checkboxes. But this only works if the label and checkbox are next to each other.
</p>
<p>
Well, that's the problem. I guess the ideal solution would be to link a label to a checkboxe using another mechanism (not using ID). I think the perfect way to do this would be to match a label to the input element whose NAME (not ID) is the same as the label's FOR attribute. What do you think?
</p>
</body>
</html>
推荐答案
在我看来，最好的办法是重命名所有复选框，通过在它们的 id 上添加一些前缀，例如 input
The best, to my mind, what you can do, is to rename all the checkboxes, by adding some prefix to their ids, for example input
<ul>
<li>
<input type="checkbox" id="input_prologue" />
<label for="input_prologue">prologue</label>
</li>
<li>
<input type="checkbox" id="input_chapter" />
<label for="input_chapter">chapter</label>
</li>
<li>
<input type="checkbox" id="input_summary" />
<label for="input_summary">summary</label>
</li>
<li>
<input type="checkbox" id="input_etc" />
<label for="input_etc">etc</label>
</li>
</ul>
这样您不会与页面上的其他 id 发生任何冲突，并且单击标签将切换复选框，而无需任何特殊的 javascript 功能.
This way you will not have any conflicts with other ids on a page, and clicking the label will toggle the checkbox without any special javascript function.
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