![可切换导航栏]( "可切换导航栏")
本文介绍了Bootstrap 4 可切换导航栏的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在尝试从 Bootstrap 3.x 迁移到 4，但我在使用新导航栏时遇到了问题.无论我选择 navbar-toggleable-x 的哪个选项，导航栏总是显示汉堡按钮，就像它被折叠一样.
此 HTML 文档演示了我的问题.我在官方文档页面上得到了它.
解决方案
自 Bootstrap 4 beta 起，toggleable 已替换为 expand.
现在它是expand"断点，而不是toggle"断点，逻辑会相应改变，所以 navbar-toggleable-md 现在是 navbar-expand-lg...
https://www.codeply.com/go/Io0duaPkqz
<button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="切换导航"><span class="navbar-toggler-icon"></span><a class="navbar-brand" href="#">Navbar</a><div class="collapse navbar-collapse" id="navbarNavDropdown"><ul class="navbar-nav"><li class="nav-item active"><a class="nav-link" href="#">首页 <span class="sr-only">(current)</span></a><li class="nav-item"><a class="nav-link" href="#">功能</a><li class="nav-item"><a class="nav-link" href="#">定价</a><li class="nav-item dropdown"><a class="nav-link dropdown-toggle" href="http://example.com" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">下拉链接</a><div class="下拉菜单" aria-labelledby="navbarDropdownMenuLink"><a class="dropdown-item" href="#">Action</a><a class="dropdown-item" href="#">另一个动作</a><a class="dropdown-item" href="#">这里还有别的东西</a>
</nav>
https://www.codeply.com/go/Io0duaPkqz
如果您希望导航栏水平展开，则需要一个 navbar-expand* 类，否则导航栏默认为移动的、垂直折叠的版本.
更多关于 Bootstrap 4 从 alpha 6 到 beta 的变化
I'm trying to migrate from Bootstrap 3.x to 4 and I'm having problems with the new navbar. No matter which options for navbar-toggleable-x I choose, navbar always shows hamburger button, like it is collapsed.
This HTML document demonstrates my problem. I got it on official documentation page.
<html>
<head>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"></script>
</head>
<body>
<nav class="navbar navbar-toggleable-md navbar-light bg-faded">
<button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" 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="navbarNavDropdown">
<ul class="navbar-nav">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></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="http://example.com" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropdown link
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Another action</a>
<a class="dropdown-item" href="#">Something else here</a>
</div>
</li>
</ul>
</div>
</nav>
</body>
</html>
解决方案
As of Bootstrap 4 beta, toggleable has been replaced with expand.
Now that it's the "expand" breakpoint, and not the "toggle" breakpoint, the logic changes accordingly so navbar-toggleable-md would now be navbar-expand-lg..
https://www.codeply.com/go/Io0duaPkqz
<nav class="navbar navbar-expand-lg navbar-light bg-faded">
<button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" 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="navbarNavDropdown">
<ul class="navbar-nav">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></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="http://example.com" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropdown link
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Another action</a>
<a class="dropdown-item" href="#">Something else here</a>
</div>
</li>
</ul>
</div>
</nav>
https://www.codeply.com/go/Io0duaPkqz
A navbar-expand* class is needed if you want the navbar to expand horizontally, otherwise the Navbar defaults to the mobile, vertically collapsed version.
More on Bootstrap 4 changes from alpha 6 to beta
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