Hướng dẫn select option bootstrap 4

Default

Custom menus need only a custom class, .form-select to trigger the custom styles. Custom styles are limited to the ’s initial appearance and cannot modify the s due to browser limitations.

<select class="form-select" aria-label="Default select example">
  <option selected>Open this select menuoption>
  <option value="1">Oneoption>
  <option value="2">Twooption>
  <option value="3">Threeoption>
select>

Sizing

You may also choose from small and large custom selects to match our similarly sized text inputs.

<select class="form-select form-select-lg mb-3" aria-label=".form-select-lg example">
  <option selected>Open this select menuoption>
  <option value="1">Oneoption>
  <option value="2">Twooption>
  <option value="3">Threeoption>
select>

<select class="form-select form-select-sm" aria-label=".form-select-sm example">
  <option selected>Open this select menuoption>
  <option value="1">Oneoption>
  <option value="2">Twooption>
  <option value="3">Threeoption>
select>

The multiple attribute is also supported:

<select class="form-select" multiple aria-label="multiple select example">
  <option selected>Open this select menuoption>
  <option value="1">Oneoption>
  <option value="2">Twooption>
  <option value="3">Threeoption>
select>

As is the size attribute:

<select class="form-select" size="3" aria-label="size 3 select example">
  <option selected>Open this select menuoption>
  <option value="1">Oneoption>
  <option value="2">Twooption>
  <option value="3">Threeoption>
select>

Disabled

Add the disabled boolean attribute on a select to give it a grayed out appearance and remove pointer events.

<select class="form-select" aria-label="Disabled select example" disabled>
  <option selected>Open this select menuoption>
  <option value="1">Oneoption>
  <option value="2">Twooption>
  <option value="3">Threeoption>
select>

Sass

Variables

$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:           $gray-200;
$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,");

$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:       $border-radius;
$form-select-box-shadow:          $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-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-transition:          $input-transition;