下拉菜单

使用 Bootstrap 下拉插件切换上下文叠加层以显示链接列表等。

概述

¥Overview

下拉菜单是可切换的上下文覆盖层，用于显示链接列表等。它们通过内置的 Bootstrap 下拉菜单 JavaScript 插件实现交互。它们通过点击切换，而不是悬停；这是有意的设计决定。

¥Dropdowns are toggleable, contextual overlays for displaying lists of links and more. They’re made interactive with the included Bootstrap dropdown JavaScript plugin. They’re toggled by clicking, not by hovering; this is an intentional design decision.

下拉菜单基于第三方库 Popper 构建，该库提供动态定位和视口检测。请务必在 Bootstrap JavaScript 代码之前添加 popper.min.js，或者使用包含 Popper 的 bootstrap.bundle.min.js / bootstrap.bundle.js。由于不需要动态定位，因此 Popper 不用于在导航栏中定位下拉菜单。

¥Dropdowns are built on a third party library, Popper, which provides dynamic positioning and viewport detection. Be sure to include popper.min.js before Bootstrap’s JavaScript or use bootstrap.bundle.min.js / bootstrap.bundle.js which contains Popper. Popper isn’t used to position dropdowns in navbars though as dynamic positioning isn’t required.

无障碍

¥Accessibility

WAI ARIA 标准定义了实际的 role="menu" 小部件，但这特定于触发操作或功能的类似应用的菜单。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。

¥The WAI ARIA standard defines an actual role="menu" widget, but this is specific to application-like menus which trigger actions or functions. ARIA menus can only contain menu items, checkbox menu items, radio button menu items, radio button groups, and sub-menus.

另一方面，Bootstrap 的下拉菜单设计为通用的，适用于各种情况和标记结构。例如，可以创建包含附加输入和表单控件（例如搜索字段或登录表单）的下拉列表。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 aria- 属性。作者必须自己包含这些更具体的属性。

¥Bootstrap’s dropdowns, on the other hand, are designed to be generic and applicable to a variety of situations and markup structures. For instance, it is possible to create dropdowns that contain additional inputs and form controls, such as search fields or login forms. For this reason, Bootstrap does not expect (nor automatically add) any of the role and aria- attributes required for true ARIA menus. Authors will have to include these more specific attributes themselves.

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，例如使用光标键在各个 .dropdown-item 元素之间移动以及使用 Esc 键关闭菜单的能力。

¥However, Bootstrap does add built-in support for most standard keyboard menu interactions, such as the ability to move through individual .dropdown-item elements using the cursor keys and close the menu with the Esc key.

示例

¥Examples

将下拉菜单的切换按钮（你的按钮或链接）和下拉菜单封装在 .dropdown 或声明 position: relative; 的其他元素中。理想情况下，你应该使用 <button> 元素作为下拉触发器，但该插件也适用于 <a> 元素。此处显示的示例在适当的情况下使用语义 <ul> 元素，但支持自定义标记。

¥Wrap the dropdown’s toggle (your button or link) and the dropdown menu within .dropdown, or another element that declares position: relative;. Ideally, you should use a <button> element as the dropdown trigger, but the plugin will work with <a> elements as well. The examples shown here use semantic <ul> elements where appropriate, but custom markup is supported.

单按钮

¥Single button

通过一些标记更改，任何单个 .btn 都可以变成下拉切换。以下是如何将它们与 <button> 元素一起使用：

¥Any single .btn can be turned into a dropdown toggle with some markup changes. Here’s how you can put them to work with <button> elements:

html

<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，但在某些情况下你可能必须使用 <a> 元素。如果你这样做，我们建议添加 role="button" 属性，以便将控件的用途恰当地传达给屏幕阅读器等辅助技术。

¥While <button> is the recommended control for a dropdown toggle, there might be situations where you have to use an <a> element. If you do, we recommend adding a role="button" attribute to appropriately convey control’s purpose to assistive technologies such as screen readers.

html

<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>

最好的部分是你也可以使用任何按钮变体来执行此操作：

¥The best part is you can do this with any button variant, too:

<!-- Example single danger button -->
<div class="btn-group">
  <button type="button" class="btn btn-danger dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
    Danger
  </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>

分割按钮

¥Split button

类似地，创建分割按钮下拉菜单，其标记实际上与单按钮下拉菜单相同，但添加了 .dropdown-toggle-split 以确保下拉插入符号周围有适当的间距。

¥Similarly, create split button dropdowns with virtually the same markup as single button dropdowns, but with the addition of .dropdown-toggle-split for proper spacing around the dropdown caret.

我们使用这个额外的类将插入符号两侧的水平 padding 缩小 25%，并移除了为常规按钮下拉菜单添加的 margin-left。这些额外的更改使插入符号保持在拆分按钮的中心，并在主按钮旁边提供了更合适大小的点击区域。

¥We use this extra class to reduce the horizontal padding on either side of the caret by 25% and remove the margin-left that’s added for regular button dropdowns. Those extra changes keep the caret centered in the split button and provide a more appropriately sized hit area next to the main button.

<!-- Example split danger button -->
<div class="btn-group">
  <button type="button" class="btn btn-danger">Danger</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>

尺寸

¥Sizing

按钮下拉菜单适用于所有尺寸的按钮，包括默认和拆分下拉按钮。

¥Button dropdowns work with buttons of all sizes, including default and split dropdown buttons.

<!-- 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

¥Dark dropdowns

Deprecated in v5.3.0

通过将 .dropdown-menu-dark 添加到现有 .dropdown-menu 上，选择较暗的下拉菜单以匹配深色导航栏或自定义样式。不需要对下拉项目进行任何更改。

¥Opt into darker dropdowns to match a dark navbar or custom style by adding .dropdown-menu-dark onto an existing .dropdown-menu. No changes are required to the dropdown items.

Heads up! Dark variants for components were deprecated in v5.3.0 with the introduction of color modes. Instead of adding .dropdown-menu-dark, set data-bs-theme="dark" on the root element, a parent wrapper, or the component itself.

html

<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：

¥And putting it to use in a navbar:

html

<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

¥Directions

在 RTL 模式下方向会翻转。因此，.dropstart 将显示在右侧。

¥Directions are flipped in RTL mode. As such, .dropstart will appear on the right side.

居中

¥Centered

使下拉菜单在父元素上带有 .dropdown-center 的切换按钮下方居中。

¥Make the dropdown menu centered below the toggle with .dropdown-center on the parent element.

html

<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

通过将 .dropup 添加到父元素来触发元素上方的下拉菜单。

¥Trigger dropdown menus above elements by adding .dropup to the parent element.

<!-- 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>

Dropup 居中

¥Dropup centered

使下拉菜单位于父元素上带有 .dropup-center 的切换按钮上方的中心。

¥Make the dropup menu centered above the toggle with .dropup-center on the parent element.

html

<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

通过将 .dropend 添加到父元素来触发元素右侧的下拉菜单。

¥Trigger dropdown menus at the right of the elements by adding .dropend to the parent element.

<!-- 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>

滴启动

¥Dropstart

通过将 .dropstart 添加到父元素来触发元素左侧的下拉菜单。

¥Trigger dropdown menus at the left of the elements by adding .dropstart to the parent element.

<!-- 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>

菜单项

¥Menu items

你可以使用 <a> 或 <button> 元素作为下拉项。

¥You can use <a> or <button> elements as dropdown items.

html

<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>

你还可以使用 .dropdown-item-text 创建非交互式下拉项。请随意使用自定义 CSS 或文本工具进一步设置样式。

¥You can also create non-interactive dropdown items with .dropdown-item-text. Feel free to style further with custom CSS or text utilities.

html

<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

¥Active

将 .active 添加到下拉列表中的项目，将其设置为活动状态。要将活动状态传达给辅助技术，请使用 aria-current 属性 - 使用当前页面的 page 值，或集合中当前项目的 true。

¥Add .active to items in the dropdown to style them as active. To convey the active state to assistive technologies, use the aria-current attribute — using the page value for the current page, or true for the current item in a set.

html

<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>

禁用

¥Disabled

将 .disabled 添加到下拉列表中的项目，将其设置为禁用。

¥Add .disabled to items in the dropdown to style them as disabled.

html

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

菜单对齐

¥Menu alignment

默认情况下，下拉菜单自动定位在距离顶部 100% 的位置，并沿着其父菜单的左侧。你可以使用定向 .drop* 类来更改此设置，但你也可以使用其他修饰符类来控制它们。

¥By default, a dropdown menu is automatically positioned 100% from the top and along the left side of its parent. You can change this with the directional .drop* classes, but you can also control them with additional modifier classes.

将 .dropdown-menu-end 添加到 .dropdown-menu 以右对齐下拉菜单。在 RTL 中使用 Bootstrap 时，方向是镜像的，这意味着 .dropdown-menu-end 将出现在左侧。

¥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.

小心！下拉菜单的定位依赖于 Popper，除非它们包含在导航栏中。

¥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>

响应式对齐

¥Responsive alignment

如果要使用响应式对齐，请通过添加 data-bs-display="static" 属性来禁用动态定位并使用响应式变体类。

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

要将下拉菜单与给定断点或更大的断点右对齐，请添加 .dropdown-menu{-sm|-md|-lg|-xl|-xxl}-end。

¥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>

要将下拉菜单左对齐给定断点或更大的断点，请添加 .dropdown-menu-end 和 .dropdown-menu{-sm|-md|-lg|-xl|-xxl}-start。

¥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.

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">
    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，由于导航栏中不使用 Popper，因此无需为下拉按钮添加 data-bs-display="static" 属性。

¥Note that you don’t need to add a data-bs-display="static" attribute to dropdown buttons in navbars, since Popper isn’t used in navbars.

对齐选项

¥Alignment options

结合上面展示的大多数选项，这里有一个小型的下拉对齐选项演示，其中包含各种下拉对齐选项。

¥Taking most of the options shown above, here’s a small kitchen sink demo of various dropdown alignment options in one place.

html

<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>

菜单内容

¥Menu content

标头

¥Headers

添加标题以标记任何下拉菜单中的操作部分。

¥Add a header to label sections of actions in any dropdown menu.

html

<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>

分隔线

¥Dividers

用分隔线分隔相关菜单项组。

¥Separate groups of related menu items with a divider.

html

<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

¥Text

将任何自由格式的文本放置在带有文本的下拉菜单中，并使用间隔工具。请注意，你可能需要额外的尺寸样式来限制菜单宽度。

¥Place any freeform text within a dropdown menu with text and use spacing utilities. Note that you’ll likely need additional sizing styles to constrain the menu width.

html

<div class="dropdown-menu p-4 text-body-secondary" 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>

表单

¥Forms

将表单放入下拉菜单中，或将其制作成下拉菜单，并使用边距或内边距实用程序为其提供所需的负空间。

¥Put a form within a dropdown menu, or make it into a dropdown menu, and use margin or padding utilities to give it the negative space you require.

html

<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>

html

<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>

下拉选项

¥Dropdown options

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

¥Use data-bs-offset or data-bs-reference to change the location of the dropdown.

html

<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

¥Auto close behavior

默认情况下，单击下拉菜单内部或外部时，下拉菜单会关闭。你可以使用 autoClose 选项来更改下拉列表的这种行为。

¥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

变量

¥Variables

Added in v5.2.0

作为 Bootstrap 不断改进的 CSS 变量方法的一部分，下拉菜单现在在 .dropdown-menu 上使用本地 CSS 变量，以增强实时自定义功能。CSS 变量的值是通过 Sass 设置的，因此仍然支持 Sass 自定义。

¥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.

scss/_dropdown.scss

--#{$prefix}dropdown-zindex: #{$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};

下拉列表项至少包含一个未在 .dropdown 上设置的变量。这允许你在 Bootstrap 默认使用回退值时提供新值。

¥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 变量进行的自定义可以在 .dropdown-menu-dark 类中看到，我们在不添加重复的 CSS 选择器的情况下覆盖特定值。

¥Customization through CSS variables can be seen on the .dropdown-menu-dark class where we override specific values without adding duplicate CSS selectors.

scss/_dropdown.scss

--#{$prefix}dropdown-color: #{$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

¥Sass variables

所有下拉菜单的变量：

¥Variables for all dropdowns:

scss/_variables.scss

$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);
$dropdown-border-radius:            var(--#{$prefix}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;
$dropdown-box-shadow:               var(--#{$prefix}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;

$dropdown-link-disabled-color:      var(--#{$prefix}tertiary-color);

$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：

¥Variables for the dark dropdown:

scss/_variables.scss

$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;

用于指示下拉菜单交互性的基于 CSS 的插入符号变量：

¥Variables for the CSS-based carets that indicate a dropdown’s interactivity:

scss/_variables.scss

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

Sass 混入

¥Sass mixins

Mixin 用于生成基于 CSS 的插入符号，可以在 scss/mixins/_caret.scss 中找到。

¥Mixins are used to generate the CSS-based carets and can be found in scss/mixins/_caret.scss.

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

¥Usage

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

¥Via data attributes or JavaScript, the dropdown plugin toggles hidden content (dropdown menus) by toggling the .show class on the parent .dropdown-menu. The data-bs-toggle="dropdown" attribute is relied on for closing dropdown menus at an application level, so it’s a good idea to always use it.

在支持触摸的设备上，打开下拉菜单会将空的 mouseover 处理程序添加到 <body> 元素的直属子元素中。这个略显丑陋的 hack 是为了绕过 iOS 事件中的怪癖委托而必须的，否则，点击下拉菜单之外的任何位置都不会触发关闭下拉菜单的代码。下拉菜单关闭后，这些额外的空 mouseover 处理程序将被删除。

¥On touch-enabled devices, opening a dropdown adds empty mouseover handlers to the immediate children of the <body> element. This admittedly ugly hack is necessary to work around a quirk in iOs’ event delegation, which would otherwise prevent a tap anywhere outside of the dropdown from triggering the code that closes the dropdown. Once the dropdown is closed, these additional empty mouseover handlers are removed.

通过数据属性

¥Via data attributes

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

¥Add data-bs-toggle="dropdown" to a link or button to toggle a dropdown.

<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

¥Via JavaScript

下拉菜单的触发元素必须包含 data-bs-toggle="dropdown"，无论你是通过 JavaScript 调用下拉菜单还是使用 data-api。

¥Dropdowns must have data-bs-toggle="dropdown" on their trigger element, regardless of whether you call your dropdown via JavaScript or use the data-api.

通过 JavaScript 调用下拉菜单：

¥Call the dropdowns via JavaScript:

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

选项

¥Options

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}'.

The final configuration object is the merged result of data-bs-config, data-bs-, and js object where the latest given key-value overrides the others.

名称	类型	默认	描述
`autoClose`	布尔值，字符串	`true`	配置下拉菜单的自动关闭行为： `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. 注意：下拉菜单始终可以通过 `Esc` 键关闭。
`boundary`	字符串，元素	`'clippingParents'`	下拉菜单的溢出约束边界（仅适用于 Popper 的 preventOverflow 修饰符）。默认情况下，它是 `clippingParents`，可以接受 HTMLElement 引用（仅通过 JavaScript）。有关更多信息，请参阅 Popper 的 detectOverflow 文档。
`display`	string	`'dynamic'`	默认情况下，我们使用 Popper 进行动态定位。使用 `static` 禁用此功能。
`offset`	数组，字符串，函数	`[0, 2]`	下拉菜单相对于其目标元素的偏移量。你可以在数据属性中传递一个以逗号分隔的字符串，例如：`data-bs-offset="10,20"`。当使用函数确定偏移量时，会使用包含 Popper 位置、引用和 Popper 矩形的对象作为其第一个参数来调用该函数。触发元素的 DOM 节点作为第二个参数传递。该函数必须返回一个包含两个数字的数组：skidding, distance.有关更多信息，请参阅 Popper 的偏移文档。
`popperConfig`	null，对象，函数	`null`	要更改 Bootstrap 的默认 Popper 配置，请参阅 Popper 配置。当使用函数创建 Popper 配置时，会使用包含 Bootstrap 默认 Popper 配置的对象来调用该函数。它可以帮助你使用默认配置并将其与你自己的配置合并。该函数必须返回 Popper 的配置对象。
`reference`	字符串，元素，对象	`'toggle'`	下拉菜单的参考元素。接受 `'toggle'`、`'parent'`、HTMLElement 引用或提供 `getBoundingClientRect` 的对象的值。有关更多信息，请参阅 Popper 的构造函数文档和虚拟元素文档。

将函数与 `popperConfig` 一起使用

¥Using function with popperConfig

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

方法

¥Methods

方法	描述
`dispose`	销毁元素的下拉菜单。（移除 DOM 元素上存储的数据）
`getInstance`	静态方法，用于获取与 DOM 元素关联的下拉列表实例，使用方法如下：`bootstrap.Dropdown.getInstance(element)`。
`getOrCreateInstance`	静态方法，返回与 DOM 元素关联的下拉列表实例，或者在未初始化的情况下创建一个新的下拉列表实例。你可以像这样使用它：`bootstrap.Dropdown.getOrCreateInstance(element)`。
`hide`	隐藏指定导航栏或选项卡式导航的下拉菜单。
`show`	显示指定导航栏或选项卡式导航的下拉菜单。
`toggle`	切换指定导航栏或选项卡式导航的下拉菜单。
`update`	更新元素下拉菜单的位置。

活动

¥Events

所有下拉事件均在切换元素上触发，然后向上冒泡。因此，你也可以在 .dropdown-menu 的父元素上添加事件监听器。hide.bs.dropdown 和 hidden.bs.dropdown 事件具有 clickEvent 属性（仅当原始事件类型为 click 时），其中包含单击事件的事件对象。

¥All dropdown events are fired at the toggling element and then bubbled up. So you can also add event listeners on the .dropdown-menu’s parent element. hide.bs.dropdown and hidden.bs.dropdown events have a clickEvent property (only when the original Event type is click) that contains an Event Object for the click event.

事件类型	描述
`hide.bs.dropdown`	当调用 `hide` 实例方法时立即触发。
`hidden.bs.dropdown`	当下拉菜单已完成对用户隐藏且 CSS 过渡已完成时触发。
`show.bs.dropdown`	当调用 `show` 实例方法时立即触发。
`shown.bs.dropdown`	当下拉菜单对用户可见且 CSS 过渡已完成时触发。

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

下拉菜单

概述

无障碍

示例

单按钮

分割按钮

尺寸

深色下拉菜单

方向

居中

放弃

Dropup 居中

掉落

滴启动

菜单项

积极的

禁用

菜单对齐

响应式对齐

对齐选项

菜单内容

标头

Dropdown header

分隔线

文本

表单

下拉选项

自动关闭行为

CSS

变量

Sass 变量

Sass 混入

用法

通过数据属性

通过 JavaScript

选项

将函数与 popperConfig 一起使用

方法

活动

将函数与 `popperConfig` 一起使用