下拉选择（Select）

使用可改变元素初始外观的自定义 CSS 来定制本地 <select>。

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默认

自定义 <select> 菜单只需一个自定义类 .form-select 即可触发自定义样式。由于浏览器的限制，自定义样式仅限于<select>的初始外观，而不能修改<option>。

html

<select class="form-select" aria-label="Default 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>

大小

您还可以选择小尺寸和大尺寸的自定义选择，以匹配我们类似尺寸的文字输入。

html

<select class="form-select form-select-lg mb-3" aria-label="Large 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>

<select class="form-select form-select-sm" aria-label="Small 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>

还支持多文件属性multiple ,（Win按住Ctrl键，macOS按住Command，可以一次选择多个选项）。

html

<select class="form-select" multiple aria-label="Multiple 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>

支持大小属性 size :

html

<select class="form-select" size="3" aria-label="Size 3 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>

禁用

在选择项上添加 disabled 布尔属性，使其显示为灰色，并移除指针事件。

html

<select class="form-select" aria-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>

CSS

Sass 变量

scss/_variables.scss

$form-select-padding-y:             $input-padding-y;
$form-select-padding-x:             $input-padding-x;
$form-select-font-family:           $input-font-family;
$form-select-font-size:             $input-font-size;
$form-select-indicator-padding:     $form-select-padding-x * 3; // Extra padding for background-image
$form-select-font-weight:           $input-font-weight;
$form-select-line-height:           $input-line-height;
$form-select-color:                 $input-color;
$form-select-bg:                    $input-bg;
$form-select-disabled-color:        null;
$form-select-disabled-bg:           $input-disabled-bg;
$form-select-disabled-border-color: $input-disabled-border-color;
$form-select-bg-position:           right $form-select-padding-x center;
$form-select-bg-size:               16px 12px; // In pixels because image dimensions
$form-select-indicator-color:       $gray-800;
$form-select-indicator:             url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'><path fill='none' stroke='#{$form-select-indicator-color}' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='m2 5 6 6 6-6'/></svg>");

$form-select-feedback-icon-padding-end: $form-select-padding-x * 2.5 + $form-select-indicator-padding;
$form-select-feedback-icon-position:    center right $form-select-indicator-padding;
$form-select-feedback-icon-size:        $input-height-inner-half $input-height-inner-half;

$form-select-border-width:        $input-border-width;
$form-select-border-color:        $input-border-color;
$form-select-border-radius:       $input-border-radius;
$form-select-box-shadow:          var(--#{$prefix}box-shadow-inset);

$form-select-focus-border-color:  $input-focus-border-color;
$form-select-focus-width:         $input-focus-width;
$form-select-focus-box-shadow:    0 0 0 $form-select-focus-width $input-btn-focus-color;

$form-select-padding-y-sm:        $input-padding-y-sm;
$form-select-padding-x-sm:        $input-padding-x-sm;
$form-select-font-size-sm:        $input-font-size-sm;
$form-select-border-radius-sm:    $input-border-radius-sm;

$form-select-padding-y-lg:        $input-padding-y-lg;
$form-select-padding-x-lg:        $input-padding-x-lg;
$form-select-font-size-lg:        $input-font-size-lg;
$form-select-border-radius-lg:    $input-border-radius-lg;

$form-select-transition:          $input-transition;