导航栏
Bootstrap 强大且响应式的导航头部（navbar）的文档和示例。包括对品牌、导航等的支持，还包括对我们的折叠插件的支持。
怎么运行的
🌐 How it works
以下是开始使用导航栏之前需要了解的内容：
🌐 Here’s what you need to know before getting started with the navbar:
- 导航栏需要一个封装的
.navbar和.navbar-expand{-sm|-md|-lg|-xl|-xxl}来实现响应式折叠以及 颜色方案 类。 - 导航栏及其内容默认是流式的。更改容器以在不同方式下限制它们的水平宽度。
- 使用我们的spacing和flex工具类来控制导航栏内的间距和对齐。
- 导航栏默认是响应式的，但你可以轻松修改它们来改变这一点。响应式行为取决于我们的 Collapse JavaScript 插件。
- 通过使用
<nav>元素来确保可访问性，或者如果使用更通用的元素如<div>，则在每个导航栏上添加role="navigation"，以明确将其标识为辅助技术用户的标志性区域。 - 使用
aria-current="page"表示当前页面，或使用aria-current="true"表示集合中的当前项目。 - v5.2.0 新增功能： 导航栏可以使用作用于
.navbar基类的 CSS 变量进行主题化。.navbar-light已被弃用，.navbar-dark已被重写，以覆盖 CSS 变量而不是添加额外样式。
The animation effect of this component is dependent on the prefers-reduced-motion media query. See the reduced motion section of our accessibility documentation.
支持的内容
🌐 Supported content
导航栏自带对一些子组件的支持。根据需要从以下选项中选择：
🌐 Navbars come with built-in support for a handful of sub-components. Choose from the following as needed:
.navbar-brand适用于你的公司、产品或项目名称。.navbar-nav用于全高且轻量的导航（包括支持下拉菜单）。.navbar-toggler用于我们的折叠插件以及其他 导航切换 功能。- 适用于任何表单控件和操作的 Flex 和间距工具。
.navbar-text用于添加垂直居中的文本字符串。.collapse.navbar-collapse用于按父级断点对导航栏内容进行分组和隐藏。- 添加一个可选的
.navbar-nav-scroll来设置一个max-height并 滚动展开的导航栏内容。
这是一个示例，展示了一个响应式浅色主题导航栏中包含的所有子组件，该导航栏会在 lg（大）断点自动折叠。
🌐 Here’s an example of all the sub-components included in a responsive light-themed navbar that automatically collapses at the lg (large) breakpoint.
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav me-auto mb-2 mb-lg-0">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</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><hr class="dropdown-divider"></li>
<li><a class="dropdown-item" href="#">Something else here</a></li>
</ul>
</li>
<li class="nav-item">
<a class="nav-link disabled" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</div>
</nav>这个示例使用了 背景 (bg-body-tertiary) 和 间距 (me-auto, mb-2, mb-lg-0, me-2) 实用类。
🌐 This example uses background (bg-body-tertiary) and spacing (me-auto, mb-2, mb-lg-0, me-2) utility classes.
品牌
🌐 Brand
.navbar-brand 可以应用于大多数元素，但锚点效果最佳，因为某些元素可能需要使用工具类或自定义样式。
🌐 The .navbar-brand can be applied to most elements, but an anchor works best, as some elements might require utility classes or custom styles.
文本
🌐 Text
在具有 .navbar-brand 类的元素中添加你的文本。
🌐 Add your text within an element with the .navbar-brand class.
<!-- As a link -->
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>
<!-- As a heading -->
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<span class="navbar-brand mb-0 h1">Navbar</span>
</div>
</nav>图片
🌐 Image
你可以将 .navbar-brand 中的文本替换为 <img>。
🌐 You can replace the text within the .navbar-brand with an <img>.
<nav class="navbar bg-body-tertiary">
<div class="container">
<a class="navbar-brand" href="#">
<img src="/docs/5.3/assets/brand/bootstrap-logo.svg" alt="Bootstrap" width="30" height="24">
</a>
</div>
</nav>图片和文本
🌐 Image and text
你还可以利用一些附加工具同时添加图片和文本。请注意在 <img> 上添加了 .d-inline-block 和 .align-text-top。
🌐 You can also make use of some additional utilities to add an image and text at the same time. Note the addition of .d-inline-block and .align-text-top on the <img>.
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">
<img src="/docs/5.3/assets/brand/bootstrap-logo.svg" alt="Logo" width="30" height="24" class="d-inline-block align-text-top">
Bootstrap
</a>
</div>
</nav>导航
🌐 Nav
导航栏导航链接基于我们的 .nav 选项构建，具有自己的修饰类，并且需要使用 toggler 类 以实现正确的响应式样式。导航栏中的导航也会扩大以占据尽可能多的水平空间，以保持你的导航栏内容稳妥对齐。
🌐 Navbar navigation links build on our .nav options with their own modifier class and require the use of toggler classes for proper responsive styling. Navigation in navbars will also grow to occupy as much horizontal space as possible to keep your navbar contents securely aligned.
在 .nav-link 上添加 .active 类以指示当前页面。
🌐 Add the .active class on .nav-link to indicate the current page.
请注意，你还应该在活动的 .nav-link 上添加 aria-current 属性。
🌐 Please note that you should also add the aria-current attribute on the active .nav-link.
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarNav">
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Features</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Pricing</a>
</li>
<li class="nav-item">
<a class="nav-link disabled" aria-disabled="true">Disabled</a>
</li>
</ul>
</div>
</div>
</nav>因为我们使用类作为导航，所以如果你愿意，你可以完全避免基于列表的方法。
🌐 And because we use classes for our navs, you can avoid the list-based approach entirely if you like.
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNavAltMarkup" aria-controls="navbarNavAltMarkup" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarNavAltMarkup">
<div class="navbar-nav">
<a class="nav-link active" aria-current="page" href="#">Home</a>
<a class="nav-link" href="#">Features</a>
<a class="nav-link" href="#">Pricing</a>
<a class="nav-link disabled" aria-disabled="true">Disabled</a>
</div>
</div>
</div>
</nav>你也可以在导航栏中使用下拉菜单。下拉菜单需要一个封装元素来进行定位，所以请确保像下面示例中那样为 .nav-item 和 .nav-link 使用单独的嵌套元素。
🌐 You can also use dropdowns in your navbar. Dropdown menus require a wrapping element for positioning, so be sure to use separate and nested elements for .nav-item and .nav-link as shown below.
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarNavDropdown">
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Features</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Pricing</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link 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>
</li>
</ul>
</div>
</div>
</nav>表单
🌐 Forms
将各种表单控件和组件放置在导航栏中：
🌐 Place various form controls and components within a navbar:
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<form class="d-flex" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</nav>.navbar 的直接子元素使用弹性布局，并且默认将使用 justify-content: space-between。根据需要使用额外的 flex 工具 来调整此行为。
🌐 Immediate child elements of .navbar use flex layout and will default to justify-content: space-between. Use additional flex utilities as needed to adjust this behavior.
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand">Navbar</a>
<form class="d-flex" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</nav>输入组也可以使用。如果你的导航栏是一个完整的表单，或者大部分是表单，你可以使用 <form> 元素作为容器，从而节省一些 HTML。
🌐 Input groups work, too. If your navbar is an entire form, or mostly a form, you can use the <form> element as the container and save some HTML.
<nav class="navbar bg-body-tertiary">
<form class="container-fluid">
<div class="input-group">
<span class="input-group-text" id="basic-addon1">@</span>
<input type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="basic-addon1"/>
</div>
</form>
</nav>这些导航栏表单也支持各种按钮。这也是一个很好的提醒，垂直对齐工具可以用来对齐不同大小的元素。
🌐 Various buttons are supported as part of these navbar forms, too. This is also a great reminder that vertical alignment utilities can be used to align different sized elements.
<nav class="navbar bg-body-tertiary">
<form class="container-fluid justify-content-start">
<button class="btn btn-outline-success me-2" type="button">Main button</button>
<button class="btn btn-sm btn-outline-secondary" type="button">Smaller button</button>
</form>
</nav>文本
🌐 Text
导航栏可以使用 .navbar-text 来包含文本。这一类会调整文本字符串的垂直对齐和水平间距。
🌐 Navbars may contain bits of text with the help of .navbar-text. This class adjusts vertical alignment and horizontal spacing for strings of text.
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<span class="navbar-text">
Navbar text with an inline element
</span>
</div>
</nav>根据需要与其他组件和工具混合搭配。
🌐 Mix and match with other components and utilities as needed.
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar w/ text</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarText" aria-controls="navbarText" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarText">
<ul class="navbar-nav me-auto mb-2 mb-lg-0">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Features</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Pricing</a>
</li>
</ul>
<span class="navbar-text">
Navbar text with an inline element
</span>
</div>
</div>
</nav>配色方案
🌐 Color schemes
v5.3.0 中的新深色导航栏 — 我们已经弃用 .navbar-dark，并推荐使用新的 data-bs-theme="dark"。在 .navbar 中添加 data-bs-theme="dark" 可启用组件特定的颜色模式。了解更多关于我们的颜色模式。
v5.2.0 新功能 — 导航栏主题现在由 CSS 变量驱动，.navbar-light 已被弃用。CSS 变量应用于 .navbar，默认使用“浅色”外观，并可以通过 .navbar-dark 覆盖。
由于 Bootstrap 结合了 Sass 和 CSS 变量，导航栏主题比以往任何时候都更容易使用。默认是我们的“浅色导航栏”，适用于浅色背景，但你也可以将 data-bs-theme="dark" 应用于 .navbar 父元素以使用深色背景。然后，使用 .bg-* 和其他实用工具进行自定义。
🌐 Navbar themes are easier than ever thanks to Bootstrap’s combination of Sass and CSS variables. The default is our “light navbar” for use with light background colors, but you can also apply data-bs-theme="dark" to the .navbar parent for dark background colors. Then, customize with .bg-* and additional utilities.
<nav class="navbar bg-dark border-bottom border-body" data-bs-theme="dark">
<!-- Navbar content -->
</nav>
<nav class="navbar bg-primary" data-bs-theme="dark">
<!-- Navbar content -->
</nav>
<nav class="navbar" style="background-color: #e3f2fd;" data-bs-theme="light">
<!-- Navbar content -->
</nav>
容器
🌐 Containers
虽然不是必需的，你可以将导航栏封装在 .container 中以将其在页面上居中——不过请注意，仍然需要一个内部容器。或者你可以在 .navbar 内添加一个容器，仅居中 固定或静态顶部导航栏 的内容。
🌐 Although it’s not required, you can wrap a navbar in a .container to center it on a page–though note that an inner container is still required. Or you can add a container inside the .navbar to only center the contents of a fixed or static top navbar.
<div class="container">
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>
</div>使用任何响应式容器来更改导航栏中内容的显示宽度。
🌐 Use any of the responsive containers to change how wide the content in your navbar is presented.
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-md">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>放置
🌐 Placement
使用我们的 位置工具 将导航栏放置在非静态位置。可以选择固定在顶部、固定在底部、顶部固定（随页面滚动直到到达顶部，然后固定在那里）或底部固定（随页面滚动直到到达底部，然后固定在那里）。
🌐 Use our position utilities to place navbars in non-static positions. Choose from fixed to the top, fixed to the bottom, stickied to the top (scrolls with the page until it reaches the top, then stays there), or stickied to the bottom (scrolls with the page until it reaches the bottom, then stays there).
固定导航栏使用 position: fixed，意味着它们从 DOM 的正常流中被抽取，可能需要自定义 CSS（例如在 <body> 上使用 padding-top）以防止与其他元素重叠。
🌐 Fixed navbars use position: fixed, meaning they’re pulled from the normal flow of the DOM and may require custom CSS (e.g., padding-top on the <body>) to prevent overlap with other elements.
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Default</a>
</div>
</nav><nav class="navbar fixed-top bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Fixed top</a>
</div>
</nav><nav class="navbar fixed-bottom bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Fixed bottom</a>
</div>
</nav><nav class="navbar sticky-top bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Sticky top</a>
</div>
</nav><nav class="navbar sticky-bottom bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Sticky bottom</a>
</div>
</nav>滚动
🌐 Scrolling
将 .navbar-nav-scroll 添加到 .navbar-nav（或其他导航栏子组件）中，以在折叠导航栏的可切换内容中启用垂直滚动。默认情况下，滚动在 75vh（或视口高度的 75%）时开始，但你可以使用本地 CSS 自定义属性 --bs-navbar-height 或自定义样式来覆盖它。在导航栏展开的较大视口中，内容将如默认导航栏中显示的那样显示。
🌐 Add .navbar-nav-scroll to a .navbar-nav (or other navbar sub-component) to enable vertical scrolling within the toggleable contents of a collapsed navbar. By default, scrolling kicks in at 75vh (or 75% of the viewport height), but you can override that with the local CSS custom property --bs-navbar-height or custom styles. At larger viewports when the navbar is expanded, content will appear as it does in a default navbar.
请注意，这种行为可能带来 overflow 的潜在缺点——当设置 overflow-y: auto（需要在此处滚动内容）时，overflow-x 相当于 auto，这会裁剪一些水平内容。
🌐 Please note that this behavior comes with a potential drawback of overflow—when setting overflow-y: auto (required to scroll the content here), overflow-x is the equivalent of auto, which will crop some horizontal content.
这是一个使用 .navbar-nav-scroll 和 style="--bs-scroll-height: 100px;" 的示例导航栏，并带有一些额外的边距工具以获得最佳间距。
🌐 Here’s an example navbar using .navbar-nav-scroll with style="--bs-scroll-height: 100px;", with some extra margin utilities for optimum spacing.
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar scroll</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarScroll" aria-controls="navbarScroll" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarScroll">
<ul class="navbar-nav me-auto my-2 my-lg-0 navbar-nav-scroll" style="--bs-scroll-height: 100px;">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
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><hr class="dropdown-divider"></li>
<li><a class="dropdown-item" href="#">Something else here</a></li>
</ul>
</li>
<li class="nav-item">
<a class="nav-link disabled" aria-disabled="true">Link</a>
</li>
</ul>
<form class="d-flex" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</div>
</nav>响应式行为
🌐 Responsive behaviors
导航栏可以使用 .navbar-toggler、.navbar-collapse 和 .navbar-expand{-sm|-md|-lg|-xl|-xxl} 类来确定其内容何时会折叠在按钮后面。结合其他工具类，你可以轻松选择何时显示或隐藏特定元素。
🌐 Navbars can use .navbar-toggler, .navbar-collapse, and .navbar-expand{-sm|-md|-lg|-xl|-xxl} classes to determine when their content collapses behind a button. In combination with other utilities, you can easily choose when to show or hide particular elements.
对于从不折叠的导航栏，在导航栏上添加 .navbar-expand 类。对于总是折叠的导航栏，不要添加任何 .navbar-expand 类。
🌐 For navbars that never collapse, add the .navbar-expand class on the navbar. For navbars that always collapse, don’t add any .navbar-expand class.
切换器
🌐 Toggler
导航栏切换器默认左对齐，但如果它们紧随像 .navbar-brand 这样的同级元素，它们会自动对齐到最右侧。反转你的标记将反转切换器的位置。下面是不同切换样式的示例。
🌐 Navbar togglers are left-aligned by default, but should they follow a sibling element like a .navbar-brand, they’ll automatically be aligned to the far right. Reversing your markup will reverse the placement of the toggler. Below are examples of different toggle styles.
在最小的断点处未显示 .navbar-brand：
🌐 With no .navbar-brand shown at the smallest breakpoint:
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarTogglerDemo01" aria-controls="navbarTogglerDemo01" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarTogglerDemo01">
<a class="navbar-brand" href="#">Hidden brand</a>
<ul class="navbar-nav me-auto mb-2 mb-lg-0">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item">
<a class="nav-link disabled" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</div>
</nav>品牌名称显示在左侧，切换器显示在右侧：
🌐 With a brand name shown on the left and toggler on the right:
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarTogglerDemo02" aria-controls="navbarTogglerDemo02" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarTogglerDemo02">
<ul class="navbar-nav me-auto mb-2 mb-lg-0">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item">
<a class="nav-link disabled" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</div>
</nav>左侧有一个切换器，右侧有品牌名称：
🌐 With a toggler on the left and brand name on the right:
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarTogglerDemo03" aria-controls="navbarTogglerDemo03" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<a class="navbar-brand" href="#">Navbar</a>
<div class="collapse navbar-collapse" id="navbarTogglerDemo03">
<ul class="navbar-nav me-auto mb-2 mb-lg-0">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item">
<a class="nav-link disabled" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</div>
</nav>外部内容
🌐 External content
有时你可能想使用折叠插件来触发一个容器元素，用于放置结构上位于 .navbar 之外的内容。因为我们的插件是基于 id 和 data-bs-target 的匹配工作的，所以这很容易实现！
🌐 Sometimes you want to use the collapse plugin to trigger a container element for content that structurally sits outside of the .navbar . Because our plugin works on the id and data-bs-target matching, that’s easily done!
<div class="collapse" id="navbarToggleExternalContent" data-bs-theme="dark">
<div class="bg-dark p-4">
<h5 class="text-body-emphasis h4">Collapsed content</h5>
<span class="text-body-secondary">Toggleable via the navbar brand.</span>
</div>
</div>
<nav class="navbar navbar-dark bg-dark">
<div class="container-fluid">
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarToggleExternalContent" aria-controls="navbarToggleExternalContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
</div>
</nav>当你这样做时，我们建议额外添加 JavaScript，以便在容器打开时以编程方式将焦点移动到该容器。否则，键盘用户和辅助技术用户可能很难找到新显示的内容——特别是如果打开的容器在文档结构中位于切换器之前。我们还建议确保切换器具有 aria-controls 属性，并指向内容容器的 id。理论上，这允许辅助技术用户直接从切换器跳转到它控制的容器——但目前对此的支持仍然相当零散。
🌐 When you do this, we recommend including additional JavaScript to move the focus programmatically to the container when it is opened. Otherwise, keyboard users and users of assistive technologies will likely have a hard time finding the newly revealed content - particularly if the container that was opened comes before the toggler in the document’s structure. We also recommend making sure that the toggler has the aria-controls attribute, pointing to the id of the content container. In theory, this allows assistive technology users to jump directly from the toggler to the container it controls–but support for this is currently quite patchy.
Offcanvas
将你可展开和折叠的导航栏转换为带有 offcanvas 组件 的离屏抽屉。我们扩展了 offcanvas 的默认样式，并使用我们的 .navbar-expand-* 类创建一个动态且灵活的导航侧边栏。
🌐 Transform your expanding and collapsing navbar into an offcanvas drawer with the offcanvas component. We extend both the offcanvas default styles and use our .navbar-expand-* classes to create a dynamic and flexible navigation sidebar.
在下面的示例中，要创建一个在所有断点下始终折叠的侧边导航栏，请完全省略 .navbar-expand-* 类。
🌐 In the example below, to create an offcanvas navbar that is always collapsed across all breakpoints, omit the .navbar-expand-* class entirely.
<nav class="navbar bg-body-tertiary fixed-top">
<div class="container-fluid">
<a class="navbar-brand" href="#">Offcanvas navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="offcanvas" data-bs-target="#offcanvasNavbar" aria-controls="offcanvasNavbar" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="offcanvas offcanvas-end" tabindex="-1" id="offcanvasNavbar" aria-labelledby="offcanvasNavbarLabel">
<div class="offcanvas-header">
<h5 class="offcanvas-title" id="offcanvasNavbarLabel">Offcanvas</h5>
<button type="button" class="btn-close" data-bs-dismiss="offcanvas" aria-label="Close"></button>
</div>
<div class="offcanvas-body">
<ul class="navbar-nav justify-content-end flex-grow-1 pe-3">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</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>
<hr class="dropdown-divider">
</li>
<li><a class="dropdown-item" href="#">Something else here</a></li>
</ul>
</li>
</ul>
<form class="d-flex mt-3" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</div>
</div>
</nav>要创建一个在特定断点如 lg 扩展为普通导航栏的侧滑导航栏，请使用 .navbar-expand-lg。
🌐 To create an offcanvas navbar that expands into a normal navbar at a specific breakpoint like lg, use .navbar-expand-lg.
<nav class="navbar navbar-expand-lg bg-body-tertiary fixed-top">
<a class="navbar-brand" href="#">Offcanvas navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="offcanvas" data-bs-target="#navbarOffcanvasLg" aria-controls="navbarOffcanvasLg" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="offcanvas offcanvas-end" tabindex="-1" id="navbarOffcanvasLg" aria-labelledby="navbarOffcanvasLgLabel">
...
</div>
</nav>
在深色导航栏中使用 offcanvas 时，请注意可能需要在 offcanvas 内容上使用深色背景，以避免文本变得难以阅读。在下面的示例中，我们将 .navbar-dark 和 .bg-dark 添加到 .navbar，.text-bg-dark 添加到 .offcanvas，.dropdown-menu-dark 添加到 .dropdown-menu，以及 .btn-close-white 添加到 .btn-close，以便在深色 offcanvas 中正确应用样式。
🌐 When using offcanvas in a dark navbar, be aware that you may need to have a dark background on the offcanvas content to avoid the text becoming illegible. In the example below, we add .navbar-dark and .bg-dark to the .navbar, .text-bg-dark to the .offcanvas, .dropdown-menu-dark to .dropdown-menu, and .btn-close-white to .btn-close for proper styling with a dark offcanvas.
<nav class="navbar navbar-dark bg-dark fixed-top">
<div class="container-fluid">
<a class="navbar-brand" href="#">Offcanvas dark navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="offcanvas" data-bs-target="#offcanvasDarkNavbar" aria-controls="offcanvasDarkNavbar" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="offcanvas offcanvas-end text-bg-dark" tabindex="-1" id="offcanvasDarkNavbar" aria-labelledby="offcanvasDarkNavbarLabel">
<div class="offcanvas-header">
<h5 class="offcanvas-title" id="offcanvasDarkNavbarLabel">Dark offcanvas</h5>
<button type="button" class="btn-close btn-close-white" data-bs-dismiss="offcanvas" aria-label="Close"></button>
</div>
<div class="offcanvas-body">
<ul class="navbar-nav justify-content-end flex-grow-1 pe-3">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</a>
<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>
<hr class="dropdown-divider">
</li>
<li><a class="dropdown-item" href="#">Something else here</a></li>
</ul>
</li>
</ul>
<form class="d-flex mt-3" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-success" type="submit">Search</button>
</form>
</div>
</div>
</div>
</nav>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，导航栏现在在 .navbar 上使用本地 CSS 变量，以增强实时自定义功能。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, navbars now use local CSS variables on .navbar for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.
--#{$prefix}navbar-padding-x: #{if($navbar-padding-x == null, 0, $navbar-padding-x)};
--#{$prefix}navbar-padding-y: #{$navbar-padding-y};
--#{$prefix}navbar-color: #{$navbar-light-color};
--#{$prefix}navbar-hover-color: #{$navbar-light-hover-color};
--#{$prefix}navbar-disabled-color: #{$navbar-light-disabled-color};
--#{$prefix}navbar-active-color: #{$navbar-light-active-color};
--#{$prefix}navbar-brand-padding-y: #{$navbar-brand-padding-y};
--#{$prefix}navbar-brand-margin-end: #{$navbar-brand-margin-end};
--#{$prefix}navbar-brand-font-size: #{$navbar-brand-font-size};
--#{$prefix}navbar-brand-color: #{$navbar-light-brand-color};
--#{$prefix}navbar-brand-hover-color: #{$navbar-light-brand-hover-color};
--#{$prefix}navbar-nav-link-padding-x: #{$navbar-nav-link-padding-x};
--#{$prefix}navbar-toggler-padding-y: #{$navbar-toggler-padding-y};
--#{$prefix}navbar-toggler-padding-x: #{$navbar-toggler-padding-x};
--#{$prefix}navbar-toggler-font-size: #{$navbar-toggler-font-size};
--#{$prefix}navbar-toggler-icon-bg: #{escape-svg($navbar-light-toggler-icon-bg)};
--#{$prefix}navbar-toggler-border-color: #{$navbar-light-toggler-border-color};
--#{$prefix}navbar-toggler-border-radius: #{$navbar-toggler-border-radius};
--#{$prefix}navbar-toggler-focus-width: #{$navbar-toggler-focus-width};
--#{$prefix}navbar-toggler-transition: #{$navbar-toggler-transition};
在 .navbar-nav 上还存在一些额外的 CSS 变量：
🌐 Some additional CSS variables are also present on .navbar-nav:
--#{$prefix}nav-link-padding-x: 0;
--#{$prefix}nav-link-padding-y: #{$nav-link-padding-y};
@include rfs($nav-link-font-size, --#{$prefix}nav-link-font-size);
--#{$prefix}nav-link-font-weight: #{$nav-link-font-weight};
--#{$prefix}nav-link-color: var(--#{$prefix}navbar-color);
--#{$prefix}nav-link-hover-color: var(--#{$prefix}navbar-hover-color);
--#{$prefix}nav-link-disabled-color: var(--#{$prefix}navbar-disabled-color);
通过 CSS 变量进行自定义可以在 .navbar-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 .navbar-dark class where we override specific values without adding duplicate CSS selectors.
--#{$prefix}navbar-color: #{$navbar-dark-color};
--#{$prefix}navbar-hover-color: #{$navbar-dark-hover-color};
--#{$prefix}navbar-disabled-color: #{$navbar-dark-disabled-color};
--#{$prefix}navbar-active-color: #{$navbar-dark-active-color};
--#{$prefix}navbar-brand-color: #{$navbar-dark-brand-color};
--#{$prefix}navbar-brand-hover-color: #{$navbar-dark-brand-hover-color};
--#{$prefix}navbar-toggler-border-color: #{$navbar-dark-toggler-border-color};
--#{$prefix}navbar-toggler-icon-bg: #{escape-svg($navbar-dark-toggler-icon-bg)};
Sass 变量
🌐 Sass variables
所有导航栏的变量：
🌐 Variables for all navbars:
$navbar-padding-y: $spacer * .5;
$navbar-padding-x: null;
$navbar-nav-link-padding-x: .5rem;
$navbar-brand-font-size: $font-size-lg;
// Compute the navbar-brand padding-y so the navbar-brand will have the same height as navbar-text and nav-link
$nav-link-height: $font-size-base * $line-height-base + $nav-link-padding-y * 2;
$navbar-brand-height: $navbar-brand-font-size * $line-height-base;
$navbar-brand-padding-y: ($nav-link-height - $navbar-brand-height) * .5;
$navbar-brand-margin-end: 1rem;
$navbar-toggler-padding-y: .25rem;
$navbar-toggler-padding-x: .75rem;
$navbar-toggler-font-size: $font-size-lg;
$navbar-toggler-border-radius: $btn-border-radius;
$navbar-toggler-focus-width: $btn-focus-width;
$navbar-toggler-transition: box-shadow .15s ease-in-out;
$navbar-light-color: rgba(var(--#{$prefix}emphasis-color-rgb), .65);
$navbar-light-hover-color: rgba(var(--#{$prefix}emphasis-color-rgb), .8);
$navbar-light-active-color: rgba(var(--#{$prefix}emphasis-color-rgb), 1);
$navbar-light-disabled-color: rgba(var(--#{$prefix}emphasis-color-rgb), .3);
$navbar-light-icon-color: rgba($body-color, .75);
$navbar-light-toggler-icon-bg: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'><path stroke='#{$navbar-light-icon-color}' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/></svg>");
$navbar-light-toggler-border-color: rgba(var(--#{$prefix}emphasis-color-rgb), .15);
$navbar-light-brand-color: $navbar-light-active-color;
$navbar-light-brand-hover-color: $navbar-light-active-color;
暗色导航栏的变量：
🌐 Variables for the dark navbar:
$navbar-dark-color: rgba($white, .55);
$navbar-dark-hover-color: rgba($white, .75);
$navbar-dark-active-color: $white;
$navbar-dark-disabled-color: rgba($white, .25);
$navbar-dark-icon-color: $navbar-dark-color;
$navbar-dark-toggler-icon-bg: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'><path stroke='#{$navbar-dark-icon-color}' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/></svg>");
$navbar-dark-toggler-border-color: rgba($white, .1);
$navbar-dark-brand-color: $navbar-dark-active-color;
$navbar-dark-brand-hover-color: $navbar-dark-active-color;
Sass 循环
🌐 Sass loops
响应式导航栏展开/折叠类（例如，.navbar-expand-lg）与 $breakpoints 映射结合，并通过 scss/_navbar.scss 中的循环生成。
// Generate series of `.navbar-expand-*` responsive classes for configuring
// where your navbar collapses.
.navbar-expand {
@each $breakpoint in map-keys($grid-breakpoints) {
$next: breakpoint-next($breakpoint, $grid-breakpoints);
$infix: breakpoint-infix($next, $grid-breakpoints);
// stylelint-disable-next-line scss/selector-no-union-class-name
&#{$infix} {
@include media-breakpoint-up($next) {
flex-wrap: nowrap;
justify-content: flex-start;
.navbar-nav {
flex-direction: row;
.dropdown-menu {
position: absolute;
}
.nav-link {
padding-right: var(--#{$prefix}navbar-nav-link-padding-x);
padding-left: var(--#{$prefix}navbar-nav-link-padding-x);
}
}
.navbar-nav-scroll {
overflow: visible;
}
.navbar-collapse {
display: flex !important; // stylelint-disable-line declaration-no-important
flex-basis: auto;
}
.navbar-toggler {
display: none;
}
.offcanvas {
// stylelint-disable declaration-no-important
position: static;
z-index: auto;
flex-grow: 1;
width: auto !important;
height: auto !important;
visibility: visible !important;
background-color: transparent !important;
border: 0 !important;
transform: none !important;
@include box-shadow(none);
@include transition(none);
// stylelint-enable declaration-no-important
.offcanvas-header {
display: none;
}
.offcanvas-body {
display: flex;
flex-grow: 0;
padding: 0;
overflow-y: visible;
}
}
}
}
}
}