导航工具条(Navbar)
Bootstrap强大的响应式导航条文件和示例。包括品牌,导览等,以及针对折叠插件的支持。
工作原理
在开始使用导航条之前,您需要了解以下内容:
- 导航条需要使用.navbar包装,并透过.navbar-expand{-sm|-md|-lg|-xl}给予响应式的折叠以及使用color scheme class。
- 导航条预设的内容宽度是浮动的,更改containers以不同的方式来限制水平宽度。
- 使用spacing及flex通用类别来控制物件在导航条的间隔及对齐。
- 导航条预设是响应式的,但也可以轻易的修改这个选项。响应式行为会使用到折叠的JavaScript插件。
- 使用nav元素确保亲和性,或者如果使用更通用的元素,如div,在每一个导航条中添加role=“navigation”为辅助技术的使用者明确标识导航区域。
- 透过设置aria-current=“page”于当前页面,或将aria-current=“true”设置于群组中的当前项目来指示目前位置
支持的内容
导航条内置对一些对子元件的支持。根据需求可从以下选项中进行选择:
.navbar-brand
用于您的公司,产品或项目名称。.navbar-nav
提供高度完整和轻便的导航(包括对下拉清单的支持)。.navbar-toggler
用于我们的折叠插件和其他navigation toggling行为。- Flex and spacing utilities 用于表单控制与行为。
.navbar-text
用于垂直居中的文本字串。.collapse.navbar-collapse
透过父层断点来群组、隐藏导航条内容。- 添加可选的
.navbar-scroll
以设置最大高度并滚动扩展的navbar内容。
以下是一个包含子元件的示例,包括在一个自动在 lg
(大)断点处摺叠的响应式导航条。
<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>
本示例使用color(bg-light)和spacing(my-2,my-lg-0,me-sm-0,my-sm-0)通用类别。
品牌
.navbar-brand
以应用于大多数元素,但锚定效果最好,因为有些元素可能需要实用程序类或自定义样式。
文本
在带有.navbar-brand
类的元素中添加文本。
<!-- 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>
图像
您可以用img替换.navbar品牌中的文本。
<nav class="navbar navbar-light bg-light">
<div class="container">
<a class="navbar-brand" href="#">
<img src="/static/doc5.0/assets/brand/bootstrap-logo.svg" alt="" width="30" height="24">
</a>
</div>
</nav>
图像和文本
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。注意在上添加了.d-inline-block
and .align-text-top
。
<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">
<img src="/static/doc5.0/assets/brand/bootstrap-logo.svg" alt="" width="30" height="24" class="d-inline-block align-text-top">
Bootstrap
</a>
</div>
</nav>
导航
导航的连接建立在我们的.nav选项上、使用专属的修饰符Class,并且需要使用toggler classes以建立适当的响应样式。在导航条中的导航元件会尽可能的占用水平空间,以保持您的导航条内容安全对齐。
启用状态-用.active -表示当前页面。可直接用于.nav-link或直属的.nav-item。
请注意,您应该在.nav-link本身上添加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>
因为我们的导航有专属的类别,依照需求你可以避免完全使用列表的方法。
<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>
您还可以在导航条的导航元件使用下拉菜单。下拉菜单需要一个包装元素进行定位,请确保为.nav-item和.nav-link使用单独及巢状的元素,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>
表单
将各种表单和元件放在导航条中:
<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>
.navbar中的直接子元素使用flex排版,预设为justify-content: space-between。根据需要使用其他flex utilities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群组也可以这样使用。如果导航条整个都是表单,或者大部分是表单,则可以使用form元素作为容器并保存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>
表单导航条也支持各种按钮。这也大大的提醒了我们可以使用垂直对齐工具来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>
文本
透过.navbar-text导航条可以包含一些文本。该class调整了文本字串的垂直对齐和水平间距。
<nav class="navbar navbar-light bg-light">
<div class="container-fluid">
<span class="navbar-text">
Navbar text with an inline element
</span>
</div>
</nav>
根据需要与其他元件和通用类别混合使用。
<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>
配色方案
由于主题class和background-color通用类别class的结合,主题化导航条从未如此简单。从.navbar-light选用浅色背景颜色,或者.navbar-dark用于深色背景颜色。然后,使用.bg-*通用类别自定义。
<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>
容器
虽然不是必需的,但您可以把导航条包装在.container中,将其置中于页面-请注意,内部的container还是必要的。或是你可以在.navbar中包装一个container,只将fixed or static top navbar的内容置中。
<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>
使用任意响应式容器以更改导航条中内容的显示宽度。
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<div class="container-md">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>
定位
使用我们的定位通用类别将导航条放置在非静态位置。选择固定到顶部、固定到底部、或粘贴到顶部(会随着页面滚动,直到物件达到顶部,并停留在原处)。固定的导航条使用position:fixed,这意味着它们会脱离正常的DOM的文件流,并且可能需要自定义CSS(例如body上的padding-top),以防止与其他元素重叠。
还要注意.sticky-top使用position:sticky,并没有被所有浏览器支持。
<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>
滚动
添加.navbar-nav-scroll
到 .navbar-nav
(或其他navbar子组件),以在折叠的navbar的可切换内容内启用垂直滚动。默认情况下,滚动以75vh(或75%的视口高度)启动,但您可以使用本地CSS自定义属性(--bs-navbar-height
或自定义风格)覆盖该属性。在较大的视口中,当导航栏展开时,内容将显示为默认导航栏中的内容。
请注意,当设置overflow-y:auto(需要在此处滚动内容)时,这种行为可能会带来溢出的缺点,overflow-x相当于auto,它将裁剪一些水平内容。
下面是一个示例navbar使用.navbar nav scroll with style=“--bs scroll height:100px;”,与一些额外的边缘实用程序的最佳间距。
<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>
响应性行为
导航条可以使用.navbar-toggler,.navbar-collapse和.navbar-expand{-sm|-md|-lg|-xl}决定它们的内容何时会摺叠。结合其他通用类别,您可以选择何时显示或隐藏特定元素。
对于不需要折叠的导航条,在导航条中加入.navbar-expand。对于总是折叠的导航条,不要加任何.navbar-expand class。
切换元素
导航条的切换元素(toggler)预设情况下会对齐左边,但如果它们位于同层级的.navbar-brand后面,它们将自动和最右边对齐。反转您的标记将对调切换元素的位置。以下是不同切换元素样式的示例。
在最小断点没有.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>
左侧有一个品牌名称,右边是切换元素:
<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>
左侧有一个切换元素,右边是品牌名称:
<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>
外部内容
有时会需要使用折叠插件来触发位于.navbar外的容器内容。因为插件是透过匹配id和data-bs-target来执行的,这将很容易完成!
<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>
当您执行此操作时,建议您添加其他JavaScript,以在打开容器时以代码控制的方式将焦点移至容器上。否则,电脑使用者与无障碍使用者可能会很难找到新显示的内容-尤其是如果打开的容器位于文档结构中的切换元素之前。我们也建议确保切换器具有aria-controls属性,指向内容容器的id。从理论上讲,这将会允许无障碍使用者直接从切换元素跳转到其控制的容器,但是对此功能的支持性目前还很少。
Sass
Variables
$navbar-padding-y: $spacer / 2;
$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) / 2;
$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
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
.
// 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;
}
}
}
}
}