:focus-within

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

:focus-within CSS 伪类表示当元素或其任意后代元素被聚焦时,将匹配该元素。换言之,它表示 :focus 伪类匹配到该元素自身或它的后代时,该伪类生效。(这也包括 shadow 树中的后代元素。)

尝试一下

label {
  display: block;
  margin-top: 1em;
}

label:focus-within {
  font-weight: bold;
}
<form>
  <p>Which flavor would you like to order?</p>
  <label>Full Name: <input name="firstName" type="text" /></label>
  <label
    >Flavor:
    <select name="flavor">
      <option>Cherry</option>
      <option>Green Tea</option>
      <option>Moose Tracks</option>
      <option>Mint Chip</option>
    </select>
  </label>
</form>

这个选择器非常有用,举个常见的例子,当用户聚焦于一个 <input> 字段时,可以用它来突出显示整个 <form> 容器。

语法

css
:focus-within {
  /* ... */
}

示例

此例子中,当表单某个文本输入框获得焦点后,表单会被设置颜色样式。

HTML

html
<p>试试在这个表单中输入点什么。</p>

<form>
  <label for="given_name">给定名称:</label>
  <input id="given_name" type="text" />
  <br />
  <label for="family_name">家庭名称:</label>
  <input id="family_name" type="text" />
</form>

CSS

css
form {
  border: 1px solid;
  color: gray;
  padding: 4px;
}

form:focus-within {
  background: #ff8;
  color: black;
}

input {
  margin: 4px;
}

结果

规范

Specification
Selectors Level 4
# the-focus-within-pseudo

浏览器兼容性

参见