简而言之，它所做的就是引用输入的id，仅此而已:

<label for="the-id-of-the-input">Input here:</label>
<input type="text" name="the-name-of-input" id="the-id-of-the-input">

它为for属性的参数标记任何输入。

<input id='myInput' type='radio'> <label for='myInput'>我的第一个Radio label </label> < br > <input id='input2' type='radio'> <label for='input2'>My 2nd Radio label </label> < br > <input id='input3' type='radio'> <label for='input3'>My 3rd Radio label </label>

在html表单中使用label for=

这可以允许在视觉上分离标签和对象，同时保持它们的链接。

示例:有一个复选框和两个标签。

你可以随意点一下这个方框来勾选/取消勾选 任何标签或 在复选框, 但不是文本，也不是输入内容……

<label for="demo1"> There is a label </label> <br /> Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Duis sem velit, ultrices et, fermentum auctor, rhoncus ut, ligula. Phasellus at purus sed purus cursus iaculis. Suspendisse fermentum. Pellentesque et arcu. Maecenas viverra. In consectetuer, lorem eu lobortis egestas, velit odio imperdiet eros, sit amet sagittis nunc mi ac neque. Sed non ipsum. Nullam venenatis gravida orci. <br /> <label for="demo1"> There is a 2nd label </label> <input id="demo1" type="checkbox">Demo 1</input>

一些有用的技巧

相同的示例，但有两个复选框和一些不同的CSS效果(如在文本中写入:选择此或取消选择此反映复选框状态。)

通过使用样式表CSS的力量，你可以做很多有趣的事情…

body { background: #DDD; } .button:before { content: 'S'; } .box:before { content: '☐'; } label.button { background: #BBB; border-top: solid 2px white;border-left: solid 2px white; border-right: solid 2px black;border-bottom: solid black 2px; } #demo2:checked ~ .but2:before { content: 'Des'; } #demo2:checked ~ .but2 { background: #CCC; border-top: solid 2px black;border-left: solid 2px black; border-right: solid 2px white;border-bottom: solid white 2px; } #demo2:checked ~ .box2:before { content: '☒'; } #demo1:checked ~ .but1 { background: #CCC; border-top: solid 2px black;border-left: solid 2px black; border-right: solid 2px white;border-bottom: solid white 2px; } #demo1:checked ~ .but1:before { content: 'Des'; } #demo1:checked ~ .box1:before { content: '☒'; } <input id="demo1" type="checkbox">Demo 1</input> <input id="demo2" type="checkbox">Demo 2</input> <br /> <label for="demo1" class="button but1">elect 1</label> - <label for="demo2" class="button but2">elect 2</label> <br /> Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Duis sem velit, ultrices et, fermentum auctor, rhoncus ut, ligula. Phasellus at purus sed purus cursus iaculis. Suspendisse fermentum. Pellentesque et arcu. Maecenas viverra. In consectetuer, lorem eu lobortis ... <br /> <label for="demo1" class="but1 button">elect this 2nd label for box 1</label> - <label class="but2 button" for="demo2">elect this other 2nd label for box 2</label> <br /><br /> <label for="demo1" class="box box1"> check 1</label> <label for="demo2" class="box2 box"> check 2</label>

用法示例:仅使用CSS切换边栏(第二段)。

在这个答案中，我只使用CSS和标签for来添加侧边栏，可以在不使用任何javascript代码的情况下进行切换。

简而言之，它所做的就是引用输入的id，仅此而已:

<label for="the-id-of-the-input">Input here:</label>
<input type="text" name="the-name-of-input" id="the-id-of-the-input">

The for attribute associates the label with a control element, as defined in the description of label in the HTML 4.01 spec. This implies, among other things, that when the label element receives focus (e.g. by being clicked on), it passes the focus on to its associated control. The association between a label and a control may also be used by speech-based user agents, which may give the user a way to ask what the associated label is, when dealing with a control. (The association may not be as obvious as in visual rendering.)

在问题的第一个例子中(没有for)，标签标记的使用没有逻辑或功能含义-它是无用的，除非您在CSS或JavaScript中使用它。

HTML规范没有强制要求将标签与控件相关联，但是Web内容可访问性指南(WCAG) 2.0要求。这在技术文档H44中有描述:使用标签元素将文本标签与表单控件关联，这也解释了隐式关联(通过嵌套，例如在标签内输入)不像通过for和id属性的显式关联那样得到广泛支持。

for属性表明这个标签代表相关的输入字段、复选框、单选按钮或与之相关的任何其他数据输入字段。 例如

<li>
    <label>{translate:blindcopy}</label>
    <a class="" href="#" title="{translate:savetemplate}" onclick="" ><i class="fa fa-list" class="button" ></i></a> &nbsp 
            <input type="text" id="BlindCopy" name="BlindCopy" class="splitblindcopy" />

</li>