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浮动标签

创建漂浮在您的input标签上的精美简单的表单标签。

在本页

示例

用.form-floating将一对<input class="form-control">和<label>元素包裹起来，以使用 Bootstrap 的文本表单字段启用浮动标签。每个<input>都需要placeholder，因为我们的纯 CSS 浮动标签方法使用:placeholder-shown伪元素。另请注意，<input>必须先出现，以便我们可以使用兄弟选择器（例如，~）。

HTML 
<div class="form-floating mb-3">
  <input type="email" class="form-control" id="floatingInput" placeholder="[email protected]">
  <label for="floatingInput">Email address</label>
</div>
<div class="form-floating">
  <input type="password" class="form-control" id="floatingPassword" placeholder="Password">
  <label for="floatingPassword">Password</label>
</div>

当有一个value已经定义的时候，<label>会自动调整到它们的浮动位置。

HTML 
<form class="form-floating">
  <input type="email" class="form-control" id="floatingInputValue" placeholder="[email protected]" value="[email protected]">
  <label for="floatingInputValue">Input with value</label>
</form>

表单验证样式也按预期工作。

HTML 
<form class="form-floating">
  <input type="email" class="form-control is-invalid" id="floatingInputInvalid" placeholder="[email protected]" value="[email protected]">
  <label for="floatingInputInvalid">Invalid input</label>
</form>

文本区域

默认情况下，添加了.form-control类的<textarea>会跟<input>的高度相同。

HTML 
<div class="form-floating">
  <textarea class="form-control" placeholder="Leave a comment here" id="floatingTextarea"></textarea>
  <label for="floatingTextarea">Comments</label>
</div>

如果需要在<textarea>上设置自定义高度，请不要使用rows属性，而是显式设置height（内联或通过自定义 CSS）来实现。

HTML 
<div class="form-floating">
  <textarea class="form-control" placeholder="Leave a comment here" id="floatingTextarea2" style="height: 100px"></textarea>
  <label for="floatingTextarea2">Comments</label>
</div>

选择器

除了.form-control，浮动标签仅在.form-select上可用。它们的工作方式相同，但与<input>不同的是，<label>始终以浮动状态显示。选择器的size和multiple属性不受支持。

HTML 
<div class="form-floating">
  <select class="form-select" id="floatingSelect" aria-label="Floating label select example">
    <option selected>Open this select menu</option>
    <option value="1">One</option>
    <option value="2">Two</option>
    <option value="3">Three</option>
  </select>
  <label for="floatingSelect">Works with selects</label>
</div>

禁用

在input、textarea或选择器上添加disabled布尔属性，使其呈现灰色外观、删除指针事件并防止聚焦。

HTML 
<div class="form-floating mb-3">
  <input type="email" class="form-control" id="floatingInputDisabled" placeholder="[email protected]" disabled>
  <label for="floatingInputDisabled">Email address</label>
</div>
<div class="form-floating mb-3">
  <textarea class="form-control" placeholder="Leave a comment here" id="floatingTextareaDisabled" disabled></textarea>
  <label for="floatingTextareaDisabled">Comments</label>
</div>
<div class="form-floating mb-3">
  <textarea class="form-control" placeholder="Leave a comment here" id="floatingTextarea2Disabled" style="height: 100px" disabled></textarea>
  <label for="floatingTextarea2Disabled">Comments</label>
</div>
<div class="form-floating">
  <select class="form-select" id="floatingSelectDisabled" aria-label="Floating label disabled select example" disabled>
    <option selected>Open this select menu</option>
    <option value="1">One</option>
    <option value="2">Two</option>
    <option value="3">Three</option>
  </select>
  <label for="floatingSelectDisabled">Works with selects</label>
</div>

只读明文

浮动标签还支持.form-control-plaintext，这有助于在不影响页面布局的情况下<input>从可编辑值切换为纯文本值。

HTML 
<div class="form-floating mb-3">
  <input type="email" readonly class="form-control-plaintext" id="floatingEmptyPlaintextInput" placeholder="[email protected]">
  <label for="floatingEmptyPlaintextInput">Empty input</label>
</div>
<div class="form-floating mb-3">
  <input type="email" readonly class="form-control-plaintext" id="floatingPlaintextInput" placeholder="[email protected]" value="[email protected]">
  <label for="floatingPlaintextInput">Input with value</label>
</div>

输入组

浮动标签也支持.input-group.

@
HTML 
<div class="input-group mb-3">
  <span class="input-group-text">@</span>
  <div class="form-floating">
    <input type="text" class="form-control" id="floatingInputGroup1" placeholder="Username">
    <label for="floatingInputGroup1">Username</label>
  </div>
</div>

当.input-group与.form-floating表单验证一起使用时，应将-feedback放在.form-floating之外，但放在.input-group. 这意味着需要使用 javascript 显示反馈。

@
Please choose a username.
HTML 
<div class="input-group has-validation">
  <span class="input-group-text">@</span>
  <div class="form-floating is-invalid">
    <input type="text" class="form-control is-invalid" id="floatingInputGroup2" placeholder="Username" required>
    <label for="floatingInputGroup2">Username</label>
  </div>
  <div class="invalid-feedback">
    Please choose a username.
  </div>
</div>

布局

使用 Bootstrap 网格系统时，请确保将表单元素放置在column列类中。

HTML 
<div class="row g-2">
  <div class="col-md">
    <div class="form-floating">
      <input type="email" class="form-control" id="floatingInputGrid" placeholder="[email protected]" value="[email protected]">
      <label for="floatingInputGrid">Email address</label>
    </div>
  </div>
  <div class="col-md">
    <div class="form-floating">
      <select class="form-select" id="floatingSelectGrid">
        <option selected>Open this select menu</option>
        <option value="1">One</option>
        <option value="2">Two</option>
        <option value="3">Three</option>
      </select>
      <label for="floatingSelectGrid">Works with selects</label>
    </div>
  </div>
</div>

Sass

变量

$form-floating-height:                  add(3.5rem, $input-height-border);
$form-floating-line-height:             1.25;
$form-floating-padding-x:               $input-padding-x;
$form-floating-padding-y:               1rem;
$form-floating-input-padding-t:         1.625rem;
$form-floating-input-padding-b:         .625rem;
$form-floating-label-height:            1.875em;
$form-floating-label-opacity:           .65;
$form-floating-label-transform:         scale(.85) translateY(-.5rem) translateX(.15rem);
$form-floating-label-disabled-color:    $gray-600;
$form-floating-transition:              opacity .1s ease-in-out, transform .1s ease-in-out;