Navbar导航栏

~~Documentation and examples for Bootstrap’s powerful, responsive navigation header, the navbar.~~ Bootstrap功能强大、响应迅速的导航标题navbar的文档和示例。~~Includes support for branding, navigation, and more, including support for our collapse plugin.~~包括对品牌、导航等的支持，包括对我们的折叠插件的支持。

~~On this page~~本页内容

How it works工作原理

~~Here’s what you need to know before getting started with the navbar:~~在开始使用导航栏之前，您需要了解以下内容：

~~Navbars require a wrapping .navbar with .navbar-expand{-sm|-md|-lg|-xl|-xxl} for responsive collapsing and color scheme classes.~~导航栏需要一个带有.navbar-expand{-sm|-md|-lg|-xl|-xxl}的包装.navbar，用于响应折叠和颜色方案类。
~~Navbars and their contents are fluid by default.~~ 默认情况下，导航栏及其内容为流体。~~Change the container to limit their horizontal width in different ways.~~更改容器以以不同方式限制其水平宽度。
~~Use our spacing and flex utility classes for controlling spacing and alignment within navbars.~~使用间距和弹性实用程序类来控制导航栏中的间距和对齐。
~~Navbars are responsive by default, but you can easily modify them to change that.~~ 默认情况下，导航栏是响应的，但您可以很容易地对其进行修改以更改。~~Responsive behavior depends on our Collapse JavaScript plugin.~~响应行为取决于Collapse JavaScript插件。
Ensure accessibility by using a <nav> element or, if using a more generic element such as a <div>, add a role="navigation" to every navbar to explicitly identify it as a landmark region for users of assistive technologies.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，例如<div>，则添加role="navigation"将其明确标识为辅助技术用户的标志性区域。
~~Indicate the current item by using aria-current="page" for the current page or aria-current="true" for the current item in a set.~~通过对于当前页面使用aria-current="page"来指示当前项目，或者对于当前集中使用aria-current="true"来指示当前项目。

~~The animation effect of this component is dependent on the prefers-reduced-motion media query.~~ 此组件的动画效果取决于prefers-reduced-motion媒体查询。~~See the reduced motion section of our accessibility documentation.~~请参阅可访问性文档中的减少运动部分。

Supported content支持的内容

~~Navbars come with built-in support for a handful of sub-components.~~ 导航栏内置了对少数子组件的支持。~~Choose from the following as needed:~~根据需要从以下选项中进行选择：

.navbar-brand ~~for your company, product, or project name.~~用于您的公司、产品或项目名称。
.navbar-nav ~~for a full-height and lightweight navigation (including support for dropdowns).~~用于实现全高度和轻量化导航（包括对下拉菜单的支持）。
.navbar-toggler ~~for use with our collapse plugin and other navigation toggling behaviors.~~用于折叠插件和其他导航切换行为。
~~Flex and spacing utilities for any form controls and actions.~~用于任何表单控件和操作的Flex和spacing实用程序。
.navbar-text ~~for adding vertically centered strings of text.~~用于添加垂直居中的文本字符串。
.collapse.navbar-collapse ~~for grouping and hiding navbar contents by a parent breakpoint.~~用于按父断点分组和隐藏导航栏内容。
~~Add an optional .navbar-scroll to set a max-height and scroll expanded navbar content.~~添加可选.navbar-scroll以设置max-height和滚动扩展的导航栏内容。

~~Here’s an example of all the sub-components included in a responsive light-themed navbar that automatically collapses at the lg (large) breakpoint.~~下面是一个包含在响应性灯光主题导航栏中的所有子组件的示例，该导航栏在lg（大）断点处自动折叠。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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="#" id="navbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</a>
<ul class="dropdown-menu" aria-labelledby="navbarDropdown">
<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" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex">
<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>

~~This example uses background (bg-light) and spacing (my-2, my-lg-0, me-sm-0, my-sm-0) utility classes.~~此示例使用背景（bg-light）和间距（my-2、my-lg-0、me-sm-0、my-sm-0）实用程序类。

Brand商标

~~The .navbar-brand can be applied to most elements, but an anchor works best, as some elements might require utility classes or custom styles.~~.navbar-brand可以应用于大多数元素，但锚点效果最好，因为某些元素可能需要实用程序类或自定义样式。

Text文本

~~Add your text within an element with the .navbar-brand class.~~使用.navbar-brand类在元素中添加文本。

<!-- As a link -->
<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>
<!-- As a heading -->
<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<span class="navbar-brand mb-0 h1">Navbar</span>
</div>
</nav>

Image形象

~~You can replace the text within the .navbar-brand with an <img>.~~您可以用<img>替换.navbar-brand中的文本。

<nav class="navbar navbar-light bg-light">
<div class="container">
<a class="navbar-brand" href="#">
<img src="/bootstrap5.1/assets/brand/bootstrap-logo.svg" alt="" width="30" height="24">
</a>
</div>
</nav>

Image and text图像和文本

~~You can also make use of some additional utilities to add an image and text at the same time.~~ 您还可以使用一些附加的实用程序来同时添加图像和文本。~~Note the addition of .d-inline-block and .align-text-top on the <img>.~~注意在<img>上添加了.d-inline-block和.align-text-top。

<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">
<img src="/bootstrap5.1/assets/brand/bootstrap-logo.svg" alt="" width="30" height="24" class="d-inline-block align-text-top">
Bootstrap
</a>
</div>
</nav>

Nav

~~Navbar navigation links build on our .nav options with their own modifier class and require the use of toggler classes for proper responsive styling.~~ 导航栏导航链接以.nav选项为基础，并带有自己的修改器类，需要使用切换器类来实现正确的响应样式。Navigation in navbars will also grow to occupy as much horizontal space as possible to keep your navbar contents securely aligned.导航栏中的导航也将尽可能多地占据水平空间，以确保导航栏内容安全对齐。

~~Add the .active class on .nav-link to indicate the current page.~~在.nav-link上添加.active类以指示当前页面。

~~Please note that you should also add the aria-current attribute on the active .nav-link.~~请注意，您还应该在活动.nav-link上添加aria-current属性。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</li>
</ul>
</div>
</div>
</nav>

~~And because we use classes for our navs, you can avoid the list-based approach entirely if you like.~~因为我们使用类来进行导航，所以如果您愿意，可以完全避免使用基于列表的方法。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</div>
</div>
</div>
</nav>

~~You can also use dropdowns in your navbar.~~ 您也可以在导航栏中使用下拉菜单。~~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.~~下拉菜单需要一个包装元素来定位，所以请确保为.nav-item和.nav-link使用单独的嵌套元素，如下所示。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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="#" id="navbarDropdownMenuLink" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown link
</a>
<ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
<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>

Forms表单

~~Place various form controls and components within a navbar:~~在导航栏中放置各种表单控件和组件：

<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<form class="d-flex">
<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>

~~Immediate child elements of .navbar use flex layout and will default to justify-content: space-between.~~ .navbar的直接子元素使用弹性布局，并将默认为justify-content: space-between。~~Use additional flex utilities as needed to adjust this behavior.~~根据需要使用其他弹性实用程序来调整此行为。

<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand">Navbar</a>
<form class="d-flex">
<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>

~~Input groups work, too.~~ 输入组也起作用。~~If your navbar is an entire form, or mostly a form, you can use the <form> element as the container and save some HTML.~~如果导航栏是一个完整的表单，或者主要是一个表单，那么可以使用<form>元素作为容器并保存一些HTML。

<nav class="navbar navbar-light bg-light">
<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>

~~Various buttons are supported as part of these navbar forms, too.~~ 这些导航栏表单也支持各种按钮。~~This is also a great reminder that vertical alignment utilities can be used to align different sized elements.~~这也是一个很好的提醒，垂直对齐实用程序可以用于对齐不同大小的元素。

<nav class="navbar navbar-light bg-light">
<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>

Text文本

~~Navbars may contain bits of text with the help of .navbar-text.~~ 导航栏可以在.navbar-text的帮助下包含文本位。~~This class adjusts vertical alignment and horizontal spacing for strings of text.~~此类调整文本字符串的垂直对齐方式和水平间距。

<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<span class="navbar-text">
Navbar text with an inline element
</span>
</div>
</nav>

~~Mix and match with other components and utilities as needed.~~根据需要与其他组件和公用设施混合和匹配。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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>

Color schemes配色方案

~~Theming the navbar has never been easier thanks to the combination of theming classes and background-color utilities.~~ 由于主题类和background-color实用程序的结合，导航栏的主题化从未如此简单。~~Choose from .navbar-light for use with light background colors, or .navbar-dark for dark background colors.~~ 选择.navbar-light用于浅色背景色，或.navbar-dark用于深色背景色。~~Then, customize with .bg-* utilities.~~然后，使用.bg-*实用程序进行自定义。

<nav class="navbar navbar-dark bg-dark">
<!-- Navbar content -->
</nav>
<nav class="navbar navbar-dark bg-primary">
<!-- Navbar content -->
</nav>
<nav class="navbar navbar-light" style="background-color: #e3f2fd;">
<!-- Navbar content -->
</nav>

Containers容器

~~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.~~ 虽然这不是必需的，但您可以将导航条包装在.container中，使其在页面上居中，但请注意，仍然需要内部容器。~~Or you can add a container inside the .navbar to only center the contents of a fixed or static top navbar.~~或者，您可以在.navbar中添加一个容器，以仅将固定或静态顶部导航栏的内容居中。

<div class="container">
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>
</div>

~~Use any of the responsive containers to change how wide the content in your navbar is presented.~~使用任何响应容器来更改导航栏中内容的显示范围。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<div class="container-md">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>

Placement位置

~~Use our position utilities to place navbars in non-static positions.~~ 使用位置实用程序将导航栏放置在非静态位置。~~Choose from fixed to the top, fixed to the bottom, or stickied to the top (scrolls with the page until it reaches the top, then stays there).~~ 选择固定到顶部、固定到底部或粘贴到顶部（滚动页面直到到达顶部，然后停留在那里）。~~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.~~固定导航条使用position: fixed，这意味着它们从DOM的正常流中被拉出来，可能需要自定义CSS（例如，<body>上的padding-top）以防止与其他元素重叠。

~~Also note that .sticky-top uses position: sticky, which isn’t fully supported in every browser.~~还要注意，.sticky-top使用position: sticky，这不是每个浏览器都完全支持的。

<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">Default</a>
</div>
</nav>

<nav class="navbar fixed-top navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">Fixed top</a>
</div>
</nav>

<nav class="navbar fixed-bottom navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">Fixed bottom</a>
</div>
</nav>

<nav class="navbar sticky-top navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">Sticky top</a>
</div>
</nav>

Scrolling滚动

~~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.~~ 将.navbar-nav-scroll添加到.navbar-nav（或其他导航栏子组件），以在折叠导航栏的可切换内容内启用垂直滚动。~~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.~~ 默认情况下，滚动速度为75vh（或视口高度的75%），但您可以使用本地CSS自定义属性--bs-navbar-height或自定义样式来覆盖它。~~At larger viewports when the navbar is expanded, content will appear as it does in a default navbar.~~当导航栏展开时，在较大的视口中，内容将显示为默认导航栏中的内容。

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.请注意，当设置overflow-y:auto（需要滚动此处的内容）时，这种行为可能存在overflow的缺点，overflow-x相当于auto，它将裁剪一些水平内容。

~~Here’s an example navbar using .navbar-nav-scroll with style="--bs-scroll-height: 100px;", with some extra margin utilities for optimum spacing.~~这里有一个使用.navbar-nav-scroll配合style="--bs-scroll-height: 100px;"的示例，它具有一些额外的余量实用程序以实现最佳间距。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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="#" id="navbarScrollingDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Link
</a>
<ul class="dropdown-menu" aria-labelledby="navbarScrollingDropdown">
<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" href="#" tabindex="-1" aria-disabled="true">Link</a>
</li>
</ul>
<form class="d-flex">
<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>

Responsive behaviors反应性行为

~~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.~~ 导航栏可以使用.navbar-toggler、.navbar-collapse和.navbar-expand{-sm|-md|-lg|-xl|-xxl}类来确定它们的内容何时折叠到按钮后面。~~In combination with other utilities, you can easily choose when to show or hide particular elements.~~结合其他实用程序，您可以轻松选择何时显示或隐藏特定元素。

~~For navbars that never collapse, add the .navbar-expand class on the navbar.~~ 对于从不折叠的导航栏，请在导航栏上添加.navbar-expand类。~~For navbars that always collapse, don’t add any .navbar-expand class.~~对于总是折叠的导航栏，不要添加任何.navbar-expand类。

Toggler

~~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.~~ 默认情况下，导航栏开关是左对齐的，但如果它们跟随.navbar-brand等同级元素，它们将自动对齐到最右侧。~~Reversing your markup will reverse the placement of the toggler.~~ 反转标记将反转切换开关的位置。~~Below are examples of different toggle styles.~~以下是不同切换样式的示例。

~~With no .navbar-brand shown at the smallest breakpoint:~~在最小断点处没有显示.navbar-brand：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex">
<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>

~~With a brand name shown on the left and toggler on the right:~~左侧显示品牌名称，右侧显示切换开关：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex">
<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>

~~With a toggler on the left and brand name on the right:~~左侧有一个开关，右侧有品牌名称：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
<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" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex">
<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>

External content外部内容

~~Sometimes you want to use the collapse plugin to trigger a container element for content that structurally sits outside of the .navbar .~~ 有时您希望使用折叠插件为结构上位于.navbar外部的内容触发容器元素。~~Because our plugin works on the id and data-bs-target matching, that’s easily done!~~因为插件工作在id和data-bs-target匹配上，这很容易做到！

Collapsed content折叠的内容

~~Toggleable via the navbar brand.~~可通过导航栏品牌切换。

<div class="collapse" id="navbarToggleExternalContent">
<div class="bg-dark p-4">
<h5 class="text-white h4">Collapsed content</h5>
<span class="text-muted">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>

~~When you do this, we recommend including additional JavaScript to move the focus programmatically to the container when it is opened.~~ 当您这样做时，我们建议在打开容器时添加其他JavaScript，以编程方式将焦点移动到容器。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. 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位于文档结构中的切换开关之前。~~We also recommend making sure that the toggler has the aria-controls attribute, pointing to the id of the content container.~~ 我们还建议确保切换器具有aria-controls属性，指向内容容器的id。~~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.~~理论上，这允许辅助技术用户直接从触发器跳到它控制的容器，但目前对此的支持还很不完善。

Offcanvas侧滑

~~Transform your expanding and collapsing navbar into an offcanvas drawer with the offcanvas plugin.~~ 使用offcanvas插件将扩展和折叠导航栏转换为offcanvas抽屉。~~We extend both the offcanvas default styles and use our .navbar-expand-* classes to create a dynamic and flexible navigation sidebar.~~我们扩展了两种非画布默认样式，并使用.navbar-expand-*类创建动态灵活的导航侧边栏。

~~In the example below, to create an offcanvas navbar that is always collapsed across all breakpoints, omit the .navbar-expand-* class entirely.~~在下面的示例中，要创建始终在所有断点之间折叠的画布外导航栏，请完全省略.navbar-expand-*类。

<nav class="navbar navbar-light bg-light 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">
<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 text-reset" 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="#" id="offcanvasNavbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</a>
<ul class="dropdown-menu" aria-labelledby="offcanvasNavbarDropdown">
<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">
<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>

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-light navbar-expand-lg bg-light 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">
<span class="navbar-toggler-icon"></span>
</button>
<div class="offcanvas offcanvas-end" tabindex="-1" id="navbarOffcanvasLg" aria-labelledby="navbarOffcanvasLgLabel">
...
</div>
</nav>

Sass

Variables变量

$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;

$navbar-dark-color:                 rgba($white, .55);
$navbar-dark-hover-color:           rgba($white, .75);
$navbar-dark-active-color:          $white;
$navbar-dark-disabled-color:        rgba($white, .25);
$navbar-dark-toggler-icon-bg:       url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'><path stroke='#{$navbar-dark-color}' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/></svg>");
$navbar-dark-toggler-border-color:  rgba($white, .1);
$navbar-light-color:                rgba($black, .55);
$navbar-light-hover-color:          rgba($black, .7);
$navbar-light-active-color:         rgba($black, .9);
$navbar-light-disabled-color:       rgba($black, .3);
$navbar-light-toggler-icon-bg:      url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'><path stroke='#{$navbar-light-color}' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/></svg>");
$navbar-light-toggler-border-color: rgba($black, .1);
$navbar-light-brand-color:                $navbar-light-active-color;
$navbar-light-brand-hover-color:          $navbar-light-active-color;
$navbar-dark-brand-color:                 $navbar-dark-active-color;
$navbar-dark-brand-hover-color:           $navbar-dark-active-color;

Loop环

~~Responsive navbar expand/collapse classes (e.g., .navbar-expand-lg) are combined with the $breakpoints map and generated through a loop in scss/_navbar.scss.~~响应性导航栏扩展/折叠类（例如，.navbar-expand-lg）与$breakpoints映射相结合，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: $navbar-nav-link-padding-x;
padding-left: $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-header {
display: none;
}
.offcanvas {
position: inherit;
bottom: 0;
z-index: 1000;
flex-grow: 1;
visibility: visible !important; // stylelint-disable-line declaration-no-important
          background-color: transparent;
border-right: 0;
border-left: 0;
@include transition(none);
transform: none;
}
.offcanvas-top,
.offcanvas-bottom {
height: auto;
border-top: 0;
border-bottom: 0;
}
.offcanvas-body {
display: flex;
flex-grow: 0;
padding: 0;
overflow-y: visible;
}
}
}
}
}