下拉菜单

使用 Bootstrap 下拉插件切换上下文覆盖以显示链接列表等。

在此页

概述

下拉菜单是可切换的上下文叠加层，用于显示链接列表等。它们与包含的 Bootstrap 下拉 JavaScript 插件交互。它们是通过单击而不是悬停来切换的；这是一个有意的设计决定。

下拉菜单建立在第三方库Popper之上，它提供动态定位和视口检测。请务必在 Bootstrap 的 JavaScript 之前包含popper.min.js或使用包含 Popper的bootstrap.bundle.min.js/ 。bootstrap.bundle.js尽管不需要动态定位，但 Popper 不用于在导航栏中定位下拉菜单。

辅助功能

WAI ARIA标准定义了一个实际的小role="menu"部件，但这是特定于触发操作或功能的类似应用程序的菜单。ARIA菜单只能包含菜单项、复选框菜单项、单选按钮菜单项、单选按钮组和子菜单。

另一方面，Bootstrap 的下拉菜单被设计为通用的并且适用于各种情况和标记结构。例如，可以创建包含额外输入和表单控件的下拉列表，例如搜索字段或登录表单。因此，Bootstrap 不期望（也不会自动添加）真正的ARIA菜单所需的任何role和属性。作者必须自己包含这些更具体的属性。aria-

但是，Bootstrap 确实添加了对大多数标准键盘菜单交互的内置支持，例如.dropdown-item使用光标键在各个元素之间移动并使用该键关闭菜单的能力Esc。

例子

将下拉菜单的开关（您的按钮或链接）和下拉菜单包裹在.dropdown，或声明position: relative;. 理想情况下，您应该使用<button>元素作为下拉触发器，但该插件也可以使用<a>元素。此处显示的示例<ul>在适当的地方使用语义元素，但支持自定义标记。

单个按钮

任何一个.btn都可以通过一些标记更改变成下拉切换。以下是如何让它们与<button>元素一起工作：

网页格式

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Dropdown button
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Another action</a></li>
    <li><a class="dropdown-item" href="#">Something else here</a></li>
  </ul>
</div>

虽然<button>是下拉切换的推荐控件，但在某些情况下您可能必须使用<a>元素。如果这样做，我们建议添加一个role="button"属性以适当地将控件的目的传达给屏幕阅读器等辅助技术。

网页格式

<div class="dropdown">
  <a class="btn btn-secondary dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
    Dropdown link
  </a>

  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Another action</a></li>
    <li><a class="dropdown-item" href="#">Something else here</a></li>
  </ul>
</div>

最好的部分是您也可以使用任何按钮变体来执行此操作：

<!-- Example single danger button -->
<div class="btn-group">
  <button type="button" class="btn btn-danger dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Action
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Another action</a></li>
    <li><a class="dropdown-item" href="#">Something else here</a></li>
    <li><hr class="dropdown-divider"></li>
    <li><a class="dropdown-item" href="#">Separated link</a></li>
  </ul>
</div>

拆分按钮

类似地，使用与单个按钮下拉列表几乎相同的标记创建拆分按钮下拉列表，但.dropdown-toggle-split在下拉插入符号周围添加了适当的间距。

我们使用这个额外的类将padding插入符号两侧的水平线减少 25%，并删除margin-left为常规按钮下拉列表添加的水平线。这些额外的更改使插入符保持在拆分按钮的中央，并在主按钮旁边提供了一个大小更合适的点击区域。

<!-- Example split danger button -->
<div class="btn-group">
  <button type="button" class="btn btn-danger">Action</button>
  <button type="button" class="btn btn-danger dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false">
    <span class="visually-hidden">Toggle Dropdown</span>
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Another action</a></li>
    <li><a class="dropdown-item" href="#">Something else here</a></li>
    <li><hr class="dropdown-divider"></li>
    <li><a class="dropdown-item" href="#">Separated link</a></li>
  </ul>
</div>

浆纱

按钮下拉菜单适用于所有大小的按钮，包括默认和拆分下拉按钮。

<!-- Large button groups (default and split) -->
<div class="btn-group">
  <button class="btn btn-secondary btn-lg dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Large button
  </button>
  <ul class="dropdown-menu">
    ...
  </ul>
</div>
<div class="btn-group">
  <button class="btn btn-secondary btn-lg" type="button">
    Large split button
  </button>
  <button type="button" class="btn btn-lg btn-secondary dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false">
    <span class="visually-hidden">Toggle Dropdown</span>
  </button>
  <ul class="dropdown-menu">
    ...
  </ul>
</div>

<div class="btn-group">
  <button class="btn btn-secondary btn-sm dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Small button
  </button>
  <ul class="dropdown-menu">
    ...
  </ul>
</div>
<div class="btn-group">
  <button class="btn btn-secondary btn-sm" type="button">
    Small split button
  </button>
  <button type="button" class="btn btn-sm btn-secondary dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false">
    <span class="visually-hidden">Toggle Dropdown</span>
  </button>
  <ul class="dropdown-menu">
    ...
  </ul>
</div>

深色下拉菜单

在 v5.3.0 中弃用

通过添加.dropdown-menu-dark到现有的.dropdown-menu. 下拉项无需更改。

小心！随着颜色模式的引入，组件的深色变体在 v5.3.0 中被弃用。不是在根元素、父包装器或组件本身上添加.dropdown-menu-dark，而是设置。data-bs-theme="dark"

网页格式

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Dropdown button
  </button>
  <ul class="dropdown-menu dropdown-menu-dark">
    <li><a class="dropdown-item active" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Another action</a></li>
    <li><a class="dropdown-item" href="#">Something else here</a></li>
    <li><hr class="dropdown-divider"></li>
    <li><a class="dropdown-item" href="#">Separated link</a></li>
  </ul>
</div>

并将其用于导航栏：

网页格式

<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNavDarkDropdown" aria-controls="navbarNavDarkDropdown" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarNavDarkDropdown">
      <ul class="navbar-nav">
        <li class="nav-item dropdown">
          <button class="btn btn-dark dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
            Dropdown
          </button>
          <ul class="dropdown-menu dropdown-menu-dark">
            <li><a class="dropdown-item" href="#">Action</a></li>
            <li><a class="dropdown-item" href="#">Another action</a></li>
            <li><a class="dropdown-item" href="#">Something else here</a></li>
          </ul>
        </li>
      </ul>
    </div>
  </div>
</nav>

方向

实时语言

在 RTL 中使用 Bootstrap 时，方向是镜像的，这意味着.dropstart将出现在右侧。

居中

使下拉菜单.dropdown-center在父元素上的切换按钮下方居中。

网页格式

<div class="dropdown-center">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Centered dropdown
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Action two</a></li>
    <li><a class="dropdown-item" href="#">Action three</a></li>
  </ul>
</div>

放弃

.dropup通过添加到父元素来触发元素上方的下拉菜单。

<!-- Default dropup button -->
<div class="btn-group dropup">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Dropup
  </button>
  <ul class="dropdown-menu">
    <!-- Dropdown menu links -->
  </ul>
</div>

<!-- Split dropup button -->
<div class="btn-group dropup">
  <button type="button" class="btn btn-secondary">
    Split dropup
  </button>
  <button type="button" class="btn btn-secondary dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false">
    <span class="visually-hidden">Toggle Dropdown</span>
  </button>
  <ul class="dropdown-menu">
    <!-- Dropdown menu links -->
  </ul>
</div>

下拉菜单居中

使下拉菜单.dropup-center在父元素上的切换按钮上方居中。

网页格式

<div class="dropup-center dropup">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Centered dropup
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Action two</a></li>
    <li><a class="dropdown-item" href="#">Action three</a></li>
  </ul>
</div>

掉落

.dropend通过添加到父元素来触发元素右侧的下拉菜单。

<!-- Default dropend button -->
<div class="btn-group dropend">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Dropend
  </button>
  <ul class="dropdown-menu">
    <!-- Dropdown menu links -->
  </ul>
</div>

<!-- Split dropend button -->
<div class="btn-group dropend">
  <button type="button" class="btn btn-secondary">
    Split dropend
  </button>
  <button type="button" class="btn btn-secondary dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false">
    <span class="visually-hidden">Toggle Dropend</span>
  </button>
  <ul class="dropdown-menu">
    <!-- Dropdown menu links -->
  </ul>
</div>

下降开始

.dropstart通过添加到父元素来触发元素左侧的下拉菜单。

<!-- Default dropstart button -->
<div class="btn-group dropstart">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Dropstart
  </button>
  <ul class="dropdown-menu">
    <!-- Dropdown menu links -->
  </ul>
</div>

<!-- Split dropstart button -->
<div class="btn-group dropstart">
  <button type="button" class="btn btn-secondary dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false">
    <span class="visually-hidden">Toggle Dropstart</span>
  </button>
  <ul class="dropdown-menu">
    <!-- Dropdown menu links -->
  </ul>
  <button type="button" class="btn btn-secondary">
    Split dropstart
  </button>
</div>

您可以使用<a>或<button>元素作为下拉项。

网页格式

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Dropdown
  </button>
  <ul class="dropdown-menu">
    <li><button class="dropdown-item" type="button">Action</button></li>
    <li><button class="dropdown-item" type="button">Another action</button></li>
    <li><button class="dropdown-item" type="button">Something else here</button></li>
  </ul>
</div>

您还可以使用创建非交互式下拉项.dropdown-item-text。随意使用自定义 CSS 或文本实用程序进一步设计样式。

网页格式

<ul class="dropdown-menu">
  <li><span class="dropdown-item-text">Dropdown item text</span></li>
  <li><a class="dropdown-item" href="#">Action</a></li>
  <li><a class="dropdown-item" href="#">Another action</a></li>
  <li><a class="dropdown-item" href="#">Something else here</a></li>
</ul>

积极的

添加.active到下拉列表中的项目以将它们设置为 active。要将活动状态传达给辅助技术，请使用aria-current属性——使用page当前页面或true集合中当前项目的值。

网页格式

<ul class="dropdown-menu">
  <li><a class="dropdown-item" href="#">Regular link</a></li>
  <li><a class="dropdown-item active" href="#" aria-current="true">Active link</a></li>
  <li><a class="dropdown-item" href="#">Another link</a></li>
</ul>

残疾人

添加.disabled到下拉列表中的项目以将它们设置为已禁用。

网页格式

<ul class="dropdown-menu">
  <li><a class="dropdown-item" href="#">Regular link</a></li>
  <li><a class="dropdown-item disabled">Disabled link</a></li>
  <li><a class="dropdown-item" href="#">Another link</a></li>
</ul>

默认情况下，下拉菜单会自动定位在距顶部 100% 的位置并沿其父项的左侧。您可以使用定向类更改此设置.drop*，但也可以使用其他修饰符类来控制它们。

Add .dropdown-menu-end to a .dropdown-menu to right align the dropdown menu. Directions are mirrored when using Bootstrap in RTL, meaning .dropdown-menu-end will appear on the left side.

Heads up! Dropdowns are positioned thanks to Popper except when they are contained in a navbar.

html

<div class="btn-group">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Right-aligned menu example
  </button>
  <ul class="dropdown-menu dropdown-menu-end">
    <li><button class="dropdown-item" type="button">Action</button></li>
    <li><button class="dropdown-item" type="button">Another action</button></li>
    <li><button class="dropdown-item" type="button">Something else here</button></li>
  </ul>
</div>

Responsive alignment

If you want to use responsive alignment, disable dynamic positioning by adding the data-bs-display="static" attribute and use the responsive variation classes.

To align right the dropdown menu with the given breakpoint or larger, add .dropdown-menu{-sm|-md|-lg|-xl|-xxl}-end.

html

<div class="btn-group">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" data-bs-display="static" aria-expanded="false">
    Left-aligned but right aligned when large screen
  </button>
  <ul class="dropdown-menu dropdown-menu-lg-end">
    <li><button class="dropdown-item" type="button">Action</button></li>
    <li><button class="dropdown-item" type="button">Another action</button></li>
    <li><button class="dropdown-item" type="button">Something else here</button></li>
  </ul>
</div>

To align left the dropdown menu with the given breakpoint or larger, add .dropdown-menu-end and .dropdown-menu{-sm|-md|-lg|-xl|-xxl}-start.

网页格式

<div class="btn-group">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" data-bs-display="static" aria-expanded="false">
    Right-aligned but left aligned when large screen
  </button>
  <ul class="dropdown-menu dropdown-menu-end dropdown-menu-lg-start">
    <li><button class="dropdown-item" type="button">Action</button></li>
    <li><button class="dropdown-item" type="button">Another action</button></li>
    <li><button class="dropdown-item" type="button">Something else here</button></li>
  </ul>
</div>

请注意，您不需要向data-bs-display="static"导航栏中的下拉按钮添加属性，因为导航栏中未使用 Popper。

对齐选项

采用上面显示的大部分选项，这里有一个小型厨房水槽演示，在一个地方展示了各种下拉对齐选项。

网页格式

<div class="btn-group">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Dropdown
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Right-aligned menu
  </button>
  <ul class="dropdown-menu dropdown-menu-end">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" data-bs-display="static" aria-expanded="false">
    Left-aligned, right-aligned lg
  </button>
  <ul class="dropdown-menu dropdown-menu-lg-end">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" data-bs-display="static" aria-expanded="false">
    Right-aligned, left-aligned lg
  </button>
  <ul class="dropdown-menu dropdown-menu-end dropdown-menu-lg-start">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group dropstart">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Dropstart
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group dropend">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Dropend
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group dropup">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Dropup
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

标头

添加标题以标记任何下拉菜单中的操作部分。

网页格式

<ul class="dropdown-menu">
  <li><h6 class="dropdown-header">Dropdown header</h6></li>
  <li><a class="dropdown-item" href="#">Action</a></li>
  <li><a class="dropdown-item" href="#">Another action</a></li>
</ul>

分频器

使用分隔线分隔相关菜单项组。

网页格式

<ul class="dropdown-menu">
  <li><a class="dropdown-item" href="#">Action</a></li>
  <li><a class="dropdown-item" href="#">Another action</a></li>
  <li><a class="dropdown-item" href="#">Something else here</a></li>
  <li><hr class="dropdown-divider"></li>
  <li><a class="dropdown-item" href="#">Separated link</a></li>
</ul>

文本

将任意格式的文本放置在带有文本的下拉菜单中，并使用间距实用程序。请注意，您可能需要额外的大小调整样式来限制菜单宽度。

网页格式

<div class="dropdown-menu p-4 text-muted" style="max-width: 200px;">
  <p>
    Some example text that's free-flowing within the dropdown menu.
  </p>
  <p class="mb-0">
    And this is more example text.
  </p>
</div>

形式

将表单放在下拉菜单中，或将其放入下拉菜单中，然后使用边距或填充实用程序为其提供所需的负空间。

网页格式

<div class="dropdown-menu">
  <form class="px-4 py-3">
    <div class="mb-3">
      <label for="exampleDropdownFormEmail1" class="form-label">Email address</label>
      <input type="email" class="form-control" id="exampleDropdownFormEmail1" placeholder="email@example.com">
    </div>
    <div class="mb-3">
      <label for="exampleDropdownFormPassword1" class="form-label">Password</label>
      <input type="password" class="form-control" id="exampleDropdownFormPassword1" placeholder="Password">
    </div>
    <div class="mb-3">
      <div class="form-check">
        <input type="checkbox" class="form-check-input" id="dropdownCheck">
        <label class="form-check-label" for="dropdownCheck">
          Remember me
        </label>
      </div>
    </div>
    <button type="submit" class="btn btn-primary">Sign in</button>
  </form>
  <div class="dropdown-divider"></div>
  <a class="dropdown-item" href="#">New around here? Sign up</a>
  <a class="dropdown-item" href="#">Forgot password?</a>
</div>

网页格式

<div class="dropdown">
  <button type="button" class="btn btn-primary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false" data-bs-auto-close="outside">
    Dropdown form
  </button>
  <form class="dropdown-menu p-4">
    <div class="mb-3">
      <label for="exampleDropdownFormEmail2" class="form-label">Email address</label>
      <input type="email" class="form-control" id="exampleDropdownFormEmail2" placeholder="email@example.com">
    </div>
    <div class="mb-3">
      <label for="exampleDropdownFormPassword2" class="form-label">Password</label>
      <input type="password" class="form-control" id="exampleDropdownFormPassword2" placeholder="Password">
    </div>
    <div class="mb-3">
      <div class="form-check">
        <input type="checkbox" class="form-check-input" id="dropdownCheck2">
        <label class="form-check-label" for="dropdownCheck2">
          Remember me
        </label>
      </div>
    </div>
    <button type="submit" class="btn btn-primary">Sign in</button>
  </form>
</div>

使用data-bs-offset或data-bs-reference更改下拉列表的位置。

网页格式

<div class="d-flex">
  <div class="dropdown me-1">
    <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false" data-bs-offset="10,20">
      Offset
    </button>
    <ul class="dropdown-menu">
      <li><a class="dropdown-item" href="#">Action</a></li>
      <li><a class="dropdown-item" href="#">Another action</a></li>
      <li><a class="dropdown-item" href="#">Something else here</a></li>
    </ul>
  </div>
  <div class="btn-group">
    <button type="button" class="btn btn-secondary">Reference</button>
    <button type="button" class="btn btn-secondary dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false" data-bs-reference="parent">
      <span class="visually-hidden">Toggle Dropdown</span>
    </button>
    <ul class="dropdown-menu">
      <li><a class="dropdown-item" href="#">Action</a></li>
      <li><a class="dropdown-item" href="#">Another action</a></li>
      <li><a class="dropdown-item" href="#">Something else here</a></li>
      <li><hr class="dropdown-divider"></li>
      <li><a class="dropdown-item" href="#">Separated link</a></li>
    </ul>
  </div>
</div>

自动关闭行为

By default, the dropdown menu is closed when clicking inside or outside the dropdown menu. You can use the autoClose option to change this behavior of the dropdown.

html

<div class="btn-group">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" data-bs-auto-close="true" aria-expanded="false">
    Default dropdown
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" data-bs-auto-close="inside" aria-expanded="false">
    Clickable inside
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" data-bs-auto-close="outside" aria-expanded="false">
    Clickable outside
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

<div class="btn-group">
  <button class="btn btn-secondary dropdown-toggle" type="button" data-bs-toggle="dropdown" data-bs-auto-close="false" aria-expanded="false">
    Manual close
  </button>
  <ul class="dropdown-menu">
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
    <li><a class="dropdown-item" href="#">Menu item</a></li>
  </ul>
</div>

CSS

Variables

Added in v5.2.0

As part of Bootstrap’s evolving CSS variables approach, dropdowns now use local CSS variables on .dropdown-menu for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.

  --#{$prefix}dropdown-zindex: #{$zindex-dropdown};
  --#{$prefix}dropdown-min-width: #{$dropdown-min-width};
  --#{$prefix}dropdown-padding-x: #{$dropdown-padding-x};
  --#{$prefix}dropdown-padding-y: #{$dropdown-padding-y};
  --#{$prefix}dropdown-spacer: #{$dropdown-spacer};
  @include rfs($dropdown-font-size, --#{$prefix}dropdown-font-size);
  --#{$prefix}dropdown-color: #{$dropdown-color};
  --#{$prefix}dropdown-bg: #{$dropdown-bg};
  --#{$prefix}dropdown-border-color: #{$dropdown-border-color};
  --#{$prefix}dropdown-border-radius: #{$dropdown-border-radius};
  --#{$prefix}dropdown-border-width: #{$dropdown-border-width};
  --#{$prefix}dropdown-inner-border-radius: #{$dropdown-inner-border-radius};
  --#{$prefix}dropdown-divider-bg: #{$dropdown-divider-bg};
  --#{$prefix}dropdown-divider-margin-y: #{$dropdown-divider-margin-y};
  --#{$prefix}dropdown-box-shadow: #{$dropdown-box-shadow};
  --#{$prefix}dropdown-link-color: #{$dropdown-link-color};
  --#{$prefix}dropdown-link-hover-color: #{$dropdown-link-hover-color};
  --#{$prefix}dropdown-link-hover-bg: #{$dropdown-link-hover-bg};
  --#{$prefix}dropdown-link-active-color: #{$dropdown-link-active-color};
  --#{$prefix}dropdown-link-active-bg: #{$dropdown-link-active-bg};
  --#{$prefix}dropdown-link-disabled-color: #{$dropdown-link-disabled-color};
  --#{$prefix}dropdown-item-padding-x: #{$dropdown-item-padding-x};
  --#{$prefix}dropdown-item-padding-y: #{$dropdown-item-padding-y};
  --#{$prefix}dropdown-header-color: #{$dropdown-header-color};
  --#{$prefix}dropdown-header-padding-x: #{$dropdown-header-padding-x};
  --#{$prefix}dropdown-header-padding-y: #{$dropdown-header-padding-y};

Dropdown items include at least one variable that is not set on .dropdown. This allows you to provide a new value while Bootstrap defaults to a fallback value.

--bs-dropdown-item-border-radius

通过 CSS 变量进行自定义可以在.dropdown-menu-dark类上看到，我们在其中覆盖特定值而不添加重复的 CSS 选择器。

  --#{$prefix}dropdown-color: #{$dropdown-dark-color};
  --#{$prefix}dropdown-bg: #{$dropdown-dark-bg};
  --#{$prefix}dropdown-border-color: #{$dropdown-dark-border-color};
  --#{$prefix}dropdown-box-shadow: #{$dropdown-dark-box-shadow};
  --#{$prefix}dropdown-link-color: #{$dropdown-dark-link-color};
  --#{$prefix}dropdown-link-hover-color: #{$dropdown-dark-link-hover-color};
  --#{$prefix}dropdown-divider-bg: #{$dropdown-dark-divider-bg};
  --#{$prefix}dropdown-link-hover-bg: #{$dropdown-dark-link-hover-bg};
  --#{$prefix}dropdown-link-active-color: #{$dropdown-dark-link-active-color};
  --#{$prefix}dropdown-link-active-bg: #{$dropdown-dark-link-active-bg};
  --#{$prefix}dropdown-link-disabled-color: #{$dropdown-dark-link-disabled-color};
  --#{$prefix}dropdown-header-color: #{$dropdown-dark-header-color};

Sass 变量

所有下拉列表的变量：

$dropdown-min-width:                10rem;
$dropdown-padding-x:                0;
$dropdown-padding-y:                .5rem;
$dropdown-spacer:                   .125rem;
$dropdown-font-size:                $font-size-base;
$dropdown-color:                    var(--#{$prefix}body-color);
$dropdown-bg:                       var(--#{$prefix}body-bg);
$dropdown-border-color:             var(--#{$prefix}border-color-translucent);
$dropdown-border-radius:            $border-radius;
$dropdown-border-width:             var(--#{$prefix}border-width);
$dropdown-inner-border-radius:      calc($dropdown-border-radius - $dropdown-border-width); // stylelint-disable-line function-disallowed-list
$dropdown-divider-bg:               $dropdown-border-color;
$dropdown-divider-margin-y:         $spacer * .5;
$dropdown-box-shadow:               $box-shadow;

$dropdown-link-color:               var(--#{$prefix}body-color);
$dropdown-link-hover-color:         $dropdown-link-color;
$dropdown-link-hover-bg:            var(--#{$prefix}tertiary-bg);

$dropdown-link-active-color:        $component-active-color;
$dropdown-link-active-bg:           $component-active-bg;

$dropdown-link-disabled-color:      $gray-500;

$dropdown-item-padding-y:           $spacer * .25;
$dropdown-item-padding-x:           $spacer;

$dropdown-header-color:             $gray-600;
$dropdown-header-padding-x:         $dropdown-item-padding-x;
$dropdown-header-padding-y:         $dropdown-padding-y;
// fusv-disable
$dropdown-header-padding:           $dropdown-header-padding-y $dropdown-header-padding-x; // Deprecated in v5.2.0
// fusv-enable

深色下拉菜单的变量：

$dropdown-dark-color:               $gray-300;
$dropdown-dark-bg:                  $gray-800;
$dropdown-dark-border-color:        $dropdown-border-color;
$dropdown-dark-divider-bg:          $dropdown-divider-bg;
$dropdown-dark-box-shadow:          null;
$dropdown-dark-link-color:          $dropdown-dark-color;
$dropdown-dark-link-hover-color:    $white;
$dropdown-dark-link-hover-bg:       rgba($white, .15);
$dropdown-dark-link-active-color:   $dropdown-link-active-color;
$dropdown-dark-link-active-bg:      $dropdown-link-active-bg;
$dropdown-dark-link-disabled-color: $gray-500;
$dropdown-dark-header-color:        $gray-500;

指示下拉列表交互性的基于 CSS 的插入符号的变量：

$caret-width:                 .3em;
$caret-vertical-align:        $caret-width * .85;
$caret-spacing:               $caret-width * .85;

混入

Mixins 用于生成基于 CSS 的插入符，可以在scss/mixins/_caret.scss.

@mixin caret-down($width: $caret-width) {
  border-top: $width solid;
  border-right: $width solid transparent;
  border-bottom: 0;
  border-left: $width solid transparent;
}

@mixin caret-up($width: $caret-width) {
  border-top: 0;
  border-right: $width solid transparent;
  border-bottom: $width solid;
  border-left: $width solid transparent;
}

@mixin caret-end($width: $caret-width) {
  border-top: $width solid transparent;
  border-right: 0;
  border-bottom: $width solid transparent;
  border-left: $width solid;
}

@mixin caret-start($width: $caret-width) {
  border-top: $width solid transparent;
  border-right: $width solid;
  border-bottom: $width solid transparent;
}

@mixin caret(
  $direction: down,
  $width: $caret-width,
  $spacing: $caret-spacing,
  $vertical-align: $caret-vertical-align
) {
  @if $enable-caret {
    &::after {
      display: inline-block;
      margin-left: $spacing;
      vertical-align: $vertical-align;
      content: "";
      @if $direction == down {
        @include caret-down($width);
      } @else if $direction == up {
        @include caret-up($width);
      } @else if $direction == end {
        @include caret-end($width);
      }
    }

    @if $direction == start {
      &::after {
        display: none;
      }

      &::before {
        display: inline-block;
        margin-right: $spacing;
        vertical-align: $vertical-align;
        content: "";
        @include caret-start($width);
      }
    }

    &:empty::after {
      margin-left: 0;
    }
  }
}

用法

通过数据属性或 JavaScript，下拉插件通过切换.show父级上的类来切换隐藏内容（下拉菜单） .dropdown-menu。该data-bs-toggle="dropdown"属性依赖于在应用程序级别关闭下拉菜单，因此始终使用它是个好主意。

在启用触摸的设备上，打开下拉列表会将空mouseover处理程序添加到元素的直接子<body>元素。这个公认的丑陋 hack 是解决iOS 事件委托中的一个怪癖所必需的，否则会阻止在下拉列表之外的任何地方点击触发关闭下拉列表的代码。关闭下拉列表后，这些额外的空mouseover处理程序将被删除。

通过数据属性

添加data-bs-toggle="dropdown"到链接或按钮以切换下拉菜单。

<div class="dropdown">
  <button type="button" data-bs-toggle="dropdown" aria-expanded="false">
    Dropdown trigger
  </button>
  <ul class="dropdown-menu">
    ...
  </ul>
</div>

通过 JavaScript

通过 JavaScript 调用下拉菜单：

const dropdownElementList = document.querySelectorAll('.dropdown-toggle')
const dropdownList = [...dropdownElementList].map(dropdownToggleEl => new bootstrap.Dropdown(dropdownToggleEl))

`data-bs-toggle="dropdown"`仍然需要

无论您是通过 JavaScript 调用下拉列表还是使用数据 API，data-bs-toggle="dropdown"始终需要出现在下拉列表的触发元素上。

选项

As options can be passed via data attributes or JavaScript, you can append an option name to data-bs-, as in data-bs-animation="{value}". Make sure to change the case type of the option name from “camelCase” to “kebab-case” when passing the options via data attributes. For example, use data-bs-custom-class="beautifier" instead of data-bs-customClass="beautifier".

As of Bootstrap 5.2.0, all components support an experimental reserved data attribute data-bs-config that can house simple component configuration as a JSON string. When an element has data-bs-config='{"delay":0, "title":123}' and data-bs-title="456" attributes, the final title value will be 456 and the separate data attributes will override values given on data-bs-config. In addition, existing data attributes are able to house JSON values like data-bs-delay='{"show":0,"hide":150}'.

Name	Type	Default	Description
`autoClose`	boolean, string	`true`	Configure the auto close behavior of the dropdown: `true` - the dropdown will be closed by clicking outside or inside the dropdown menu. `false` - the dropdown will be closed by clicking the toggle button and manually calling `hide` or `toggle` method. (Also will not be closed by pressing `Esc` key) `'inside'` - the dropdown will be closed (only) by clicking inside the dropdown menu. `'outside'` - the dropdown will be closed (only) by clicking outside the dropdown menu. Note: the dropdown can always be closed with the `Esc` key.
`boundary`	string, element	`'clippingParents'`	Overflow constraint boundary of the dropdown menu (applies only to Popper’s preventOverflow modifier). By default it’s `clippingParents` and can accept an HTMLElement reference (via JavaScript only). For more information refer to Popper’s detectOverflow docs.
`display`	string	`'dynamic'`	By default, we use Popper for dynamic positioning. Disable this with `static`.
`offset`	array, string, function	`[0, 2]`	Offset of the dropdown relative to its target. You can pass a string in data attributes with comma separated values like: `data-bs-offset="10,20"`. When a function is used to determine the offset, it is called with an object containing the popper placement, the reference, and popper rects as its first argument. The triggering element DOM node is passed as the second argument. The function must return an array with two numbers: skidding, distance. For more information refer to Popper’s offset docs.
`popperConfig`	null, object, function	`null`	要更改 Bootstrap 的默认 Popper 配置，请参阅Popper 的配置。当一个函数被用来创建 Popper 配置时，它被调用一个包含 Bootstrap 默认 Popper 配置的对象。它可以帮助您使用默认设置并将其与您自己的配置合并。该函数必须返回 Popper 的配置对象。
`reference`	字符串、元素、对象	`'toggle'`	下拉菜单的引用元素。接受`'toggle'`、`'parent'`、 HTMLElement 引用或提供的对象的值`getBoundingClientRect`。有关更多信息，请参阅 Popper 的构造函数文档和虚拟元素文档。

使用函数`popperConfig`

const dropdown = new bootstrap.Dropdown(element, {
  popperConfig(defaultBsPopperConfig) {
    // const newPopperConfig = {...}
    // use defaultBsPopperConfig if needed...
    // return newPopperConfig
  }
})

方法

方法	描述
`dispose`	销毁元素的下拉列表。（删除存储在 DOM 元素上的数据）
`getInstance`	允许您获取与 DOM 元素关联的下拉实例的静态方法，您可以像这样使用它`bootstrap.Dropdown.getInstance(element)`：
`getOrCreateInstance`	返回与 DOM 元素关联的下拉列表实例的静态方法，或者在未初始化的情况下创建一个新的实例。你可以像这样使用它`bootstrap.Dropdown.getOrCreateInstance(element)`：
`hide`	隐藏给定导航栏或选项卡式导航的下拉菜单。
`show`	显示给定导航栏或选项卡式导航的下拉菜单。
`toggle`	切换给定导航栏或选项卡式导航的下拉菜单。
`update`	更新元素下拉列表的位置。

事件

所有下拉事件都在切换元素处触发，然后向上冒泡。因此，您还可以在.dropdown-menu的父元素上添加事件侦听器。hide.bs.dropdown和hidden.bs.dropdown事件有一个clickEvent属性（仅当原始事件类型为click），其中包含单击事件的事件对象。

事件类型	描述
`hide.bs.dropdown`	`hide`调用实例方法时立即触发。
`hidden.bs.dropdown`	当下拉列表完成对用户隐藏且 CSS 转换完成时触发。
`show.bs.dropdown`	`show`调用实例方法时立即触发。
`shown.bs.dropdown`	当下拉菜单对用户可见且 CSS 转换完成时触发。

const myDropdown = document.getElementById('myDropdown')
myDropdown.addEventListener('show.bs.dropdown', event => {
  // do something...
})

下拉菜单

概述

辅助功能

例子

单个按钮

拆分按钮

浆纱

深色下拉菜单

方向

实时语言

居中

放弃

下拉菜单居中

掉落

下降开始

菜单项

积极的

残疾人

菜单排列

Responsive alignment

对齐选项

菜单内容

标头

分频器

文本

形式

自动关闭行为

CSS

Variables

Sass 变量

混入

用法

通过数据属性

通过 JavaScript

`data-bs-toggle="dropdown"`仍然需要

选项

使用函数`popperConfig`

方法

事件

下拉菜单

概述

辅助功能

例子

单个按钮

拆分按钮

浆纱

深色下拉菜单

方向

实时语言

居中

放弃

下拉菜单居中

掉落

下降开始

菜单项

积极的

残疾人

菜单排列

Responsive alignment

对齐选项

菜单内容

标头

下拉标题

分频器

文本

形式

下拉选项

自动关闭行为

CSS

Variables

Sass 变量

混入

用法

通过数据属性

通过 JavaScript

data-bs-toggle="dropdown"仍然需要

选项

使用函数popperConfig

方法

事件

`data-bs-toggle="dropdown"`仍然需要

使用函数`popperConfig`