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、用于显示链接列表及其他内容的上下文覆盖层。它们通过包含的 Bootstrap 下拉 JavaScript 插件实现交互功能。下拉菜单是通过点击切换的，而不是通过悬停切换；这是一个刻意的设计决定。

🌐 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.

下拉菜单是基于第三方库 Popper 构建的，该库提供动态定位和视口检测。确保在引入 Bootstrap 的 JavaScript 之前包含 popper.min.js，或者使用包含 Popper 的 bootstrap.bundle.min.js / bootstrap.bundle.js。不过，在导航栏中，下拉菜单并不使用 Popper 来定位，因为不需要动态定位。

🌐 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 标准定义了一个实际的 role="menu" 小部件，但这仅适用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菜单，如搜索字段或登录表单。因此，Bootstrap 不会期望（也不会自动添加）实现真正 ARIA 菜单所需的任何 role 和 aria- 属性。作者需要自己包含这些更具体的属性。

然而，Bootstrap 确实为大多数标准键盘菜单交互添加了内置支持，例如使用光标键在各个 .dropdown-item 元素之间移动，并使用 Esc 键关闭菜单。

示例

🌐 Examples

将下拉菜单的切换项（你的按钮或链接）和下拉菜单封装在 .dropdown 内，或者其他声明了 position: relative; 的元素内。理想情况下，你应该使用 <button> 元素作为下拉触发器，但该插件也可以与 <a> 元素一起使用。这里展示的示例在适当情况下使用了语义化的 <ul> 元素，但也支持自定义标记。

🌐 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

任何单个 .btn 都可以通过一些标记更改变成下拉切换。以下是如何将它们与 <button> 元素配合使用的方法：

🌐 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，但可能会有需要使用 <a> 元素的情况。如果使用了，我们建议添加一个 role="button" 属性，以适当地向辅助技术（例如屏幕阅读器）传达控件的用途。

🌐 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

同样，创建分割按钮下拉菜单，其标记几乎与单按钮下拉菜单相同，但需添加 .dropdown-toggle-split 以便在下拉箭头周围保持适当的间距。

🌐 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来将光标两侧的水平 padding 减少 25%，并移除常规按钮下拉菜单中添加的 margin-left。这些额外的更改保持了分割按钮中光标的居中，并在主按钮旁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

通过在现有的 .dropdown-menu 上添加 .dropdown-menu-dark 来选择更深色的下拉菜单，以匹配深色导航栏或自定义样式。下拉菜单项无需更改。

🌐 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

在从右到左模式下，方向会翻转。 因此，.dropstart 将显示在右侧。

居中

🌐 Centered

将下拉菜单在切换按钮下方居中，并在父元素上使用 .dropdown-center。

🌐 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

通过在父元素中添加 .dropup 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

将下拉菜单在切换按钮上方居中，并在父元素上使用 .dropup-center。

🌐 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

通过在父元素中添加 .dropend 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

通过在父元素中添加 .dropstart 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>

你也可以使用 .dropdown-item-text 创建非交互式下拉项。可以随意使用自定义 CSS 或文本工具进一步美化样式。

🌐 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 添加到下拉菜单中的项目以将其样式设为激活状态。为了向辅助技术传达激活状态，请使用 aria-current 属性——对于当前页面使用 page 值，对于集合中的当前项目使用 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 添加到下拉菜单中的项目，以 将它们设置为禁用样式。

🌐 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，下拉菜单会自动定位在父元素顶部的100%处，并沿着左侧。你可以使用方向性的 .drop* 类来改变它的位置，也可以通过额外的修饰类来控制它们。

🌐 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 以将下拉菜单右对齐。在使用 RTL 的 Bootstrap 时，方向会镜像，这意味着 .dropdown-menu-end 会出现在左侧。

🌐 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.

注意! 下拉菜单的位置由 Popper 决定，除非它们包含在导航栏中。

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

如果你想使用响应式对齐，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.

要将下拉菜单在给定断点或更大屏幕上右对齐，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>

要将下拉菜单在给定断点或更大屏幕尺寸下左对齐，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，你不需要在导航栏的下拉按钮中添加 data-bs-display="static" 属性，因为导航栏中不使用 Popper。

🌐 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

将任何自由格式文本放入带有文本的下拉菜单中，并使用间距工具。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

在下拉菜单中放置一个表单，或将其制作成下拉菜单，并使用 margin 或 padding 工具来提供所需的负空间。

🌐 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 来更改下拉菜单的位置。

🌐 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，点击下拉菜单内部或外部时，下拉菜单会关闭。你可以使用 autoClose 选项来更改下拉菜单的此行为。

🌐 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 不断发展的 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。CSS 变量的值通过 Sass 设置，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};

下拉项至少包含一个在 .dropdown 上未设置的变量。这允许你在 Bootstrap 使用回退值时提供一个新的值。

--bs-dropdown-item-border-radius

通过 CSS 变量进行自定义可以在 .dropdown-menu-dark 类中看到，我们通过覆盖特定值而无需添加重复的 CSS 选择器。

🌐 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

暗色下拉菜单的变量:

🌐 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 的光标，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，下拉插件通过在父元素 .dropdown-menu 上切换 .show 类来切换隐藏内容（下拉菜单）。data-bs-toggle="dropdown" 属性用于在应用级别关闭下拉菜单，因此最好始终使用它。

🌐 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.

在触摸设备上，打开下拉菜单会在 <body> 元素的直接子元素上添加空的 mouseover 处理程序。这种明显不优雅的做法是为了绕过 iOS 事件委托中的一个奇怪问题，否则下拉菜单外的任何点击都无法触发关闭下拉菜单的代码。一旦下拉菜单关闭，这些额外的空 mouseover 处理程序就会被移除。

通过数据属性

🌐 Via data attributes

在链接或按钮上添加 data-bs-toggle="dropdown" 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具有 data-bs-toggle="dropdown"，无论你是通过 JavaScript 调用下拉菜单还是使用 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.

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`	To change Bootstrap’s default Popper config, see Popper’s configuration. When a function is used to create the Popper configuration, it’s called with an object that contains the Bootstrap’s default Popper configuration. It helps you use and merge the default with your own configuration. The function must return a configuration object for Popper.
`reference`	string, element, object	`'toggle'`	Reference element of the dropdown menu. Accepts the values of `'toggle'`, `'parent'`, an HTMLElement reference or an object providing `getBoundingClientRect`. For more information refer to Popper’s constructor docs and virtual element docs.

使用带有 `popperConfig` 的函数

🌐 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。（删除 DOM 元素上的存储数据）
`getInstance`	静态方法，用于获取与 DOM 元素关联的下拉菜单实例，你可以这样使用它：`bootstrap.Dropdown.getInstance(element)`。
`getOrCreateInstance`	静态方法，返回与 DOM 元素关联的下拉菜单实例，如果未初始化则创建一个新的。你可以这样使用它：`bootstrap.Dropdown.getOrCreateInstance(element)`。
`hide`	隐藏给定导航栏或选项卡导航的下拉菜单。
`show`	显示给定导航栏或选项卡导航的下拉菜单。
`toggle`	切换给定导航栏或选项卡导航的下拉菜单。
`update`	更新元素下拉菜单的位置。

事件

🌐 Events

所有下拉事件都会在切换元素上触发，然后向上传播。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 事件有一个 clickEvent 属性（仅当原始事件类型为 click 时），该属性包含点击事件的 Event 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`	当下拉菜单完全从用户界面隐藏且 CSS 过渡完成时触发。
`show.bs.dropdown`	当调用 `show` 实例方法时立即触发。
`shown.bs.dropdown`	当下拉菜单显示给用户且 CSS 过渡完成时触发。

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

使用带有 popperConfig 的函数

方法

事件

使用带有 `popperConfig` 的函数