Bootstrap 下拉菜单 - 显示第二个 bootstrap 导航栏

Question

我有一个 Bootstrap 3 navbar，具有开箱即用的 dropdown-menu 功能

有没有办法在按钮的 dropdown-toggle 上设置第二个导航栏 displayed/transitioned？我们希望格式正确

<nav class="navbar navbar-default">
  <div class="container">

显示我们的子菜单项。类似于单击 "More" 按钮时 www.bbc.co.uk 站点的工作方式 - 显示第二个集中式导航栏而不是 dropdown-menu（再次按下按钮时隐藏）

Answer 1

Bootstrap 为您提供了不同的内置组件，您可以根据需要使用。

它还有一个 Collapse 组件，可用于在我们单击某个特定元素时打开和关闭块。

您可以在该组件的 .navbar 内部和 .collapse 主体内部使用该组件。如果需要，您可以使用更多 .dropdown 项。

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<nav class="navbar navbar-default">
  <div class="container-fluid">
    <!-- Brand and toggle get grouped for better mobile display -->
    <div class="navbar-header">
      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
        <span class="sr-only">Toggle navigation</span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
      <a class="navbar-brand" href="#">Brand</a>
    </div>

    <!-- Collect the nav links, forms, and other content for toggling -->
    <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
      <div class="clearfix">
        <ul class="nav navbar-nav">
          <li class="active"><a href="#">Link <span class="sr-only">(current)</span></a></li>
          <li><a href="#">Link</a></li>
          <li class="dropdown">
            <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Dropdown <span class="caret"></span></a>
            <ul class="dropdown-menu">
              <li><a href="#">Action</a></li>
              <li><a href="#">Another action</a></li>
              <li><a href="#">Something else here</a></li>
              <li role="separator" class="divider"></li>
              <li><a href="#">Separated link</a></li>
              <li role="separator" class="divider"></li>
              <li><a href="#">One more separated link</a></li>
            </ul>
          </li>
        </ul>
        <form class="navbar-form navbar-left">
          <div class="form-group">
            <input type="text" class="form-control" placeholder="Search">
          </div>
          <button type="submit" class="btn btn-default">Submit</button>
        </form>
        <ul class="nav navbar-nav navbar-right">
          <li><a href="#">Link</a></li>
          <li class="dropdown">
            <a href="#" class="dropdown-toggle" data-toggle="collapse" data-target="#collapseExample" aria-expanded="false" aria-controls="collapseExample">Dropdown <span class="caret"></span></a>
          </li>
        </ul>
      </div>
      <div class="collapsible-menu">
        <div class="collapse" id="collapseExample">
          <div class="well">
            Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident.
          </div>
        </div>
      </div>
    </div><!-- /.navbar-collapse -->
  </div><!-- /.container-fluid -->
</nav>

Answer 2

如果您在 Bootstrap 3 中寻找不止一个下拉菜单，天真地不支持。但是，您可以实现它。

下面是一些示例 HTML 标记：

<nav class="navbar navbar-inverse navbar-fixed-top">
    <div class="container-fluid">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-navbar-collapse-1" aria-expanded="false">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="#">Brand</a>
        </div>
        <div class="collapse navbar-collapse" id="bs-navbar-collapse-1">
            <ul class="nav navbar-nav">
                <li><a href="index.php">Home</a></li>
                <li class="dropdown">
                    <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Dropdown <span class="caret"></span></a>
                    <ul class="dropdown-menu">
                         <li><a href="#">Menu Item</a></li>
                         <li><a href="#">Menu Item</a></li>
                         <li class="dropdown-submenu">
                             <a tabindex="-1" href="#" class="dropdown-submenu-toggle">Second Dropdown <b class="caret"></b></a>
                             <ul class="dropdown-menu">
                                 <li><a href="#">Sub-Menu Item</a></li>
                                 <li><a href="#">Sub-Menu Item</a></li>
                                 <li><a href="#">Sub-Menu Item</a></li>
                             </ul>
                         </li>
                         <li><a href="#">Menu Item</a></li>
                         <li><a href="#">Menu Item</a></li>
                     </ul>
                 </li>
             </ul>
         </div><!-- /.navbar-collapse -->
      </div><!-- /container -->
    </nav>

现在，让我们让 CSS 完成大部分繁重的工作，并尽可能多地使用本机 Bootstrap 类。只需将此自定义 CSS 添加到您的样式表，在 Bootstrap 的主样式表之后。

/* NEW 2nd-Level Dropdown CSS START */
.dropdown-submenu{position: relative;}
.dropdown-submenu .caret{-webkit-transform: rotate(-90deg); transform: rotate(-90deg);}
.dropdown-submenu > .dropdown-menu {top:0; left:100%; margin-top:-6px; margin-left:-1px;}
.dropdown-submenu.open > a:after{border-left-color:#fff;}
.dropdown-submenu.open > .dropdown-menu, .dropdown-submenu.open > .dropdown-menu {display: block;}
.dropdown-submenu .dropdown-menu{margin-bottom: 8px;}
.navbar-default .navbar-nav .open .dropdown-menu .dropdown-submenu ul{background-color: #f6f6f6;}
.navbar-inverse .navbar-nav .open .dropdown-menu .dropdown-submenu ul{background-color:#333;}
.navbar .navbar-nav .open .dropdown-submenu .dropdown-menu > li > a{padding-left: 30px;}
@media screen and (min-width:992px){
    .dropdown-submenu .dropdown-menu{margin-bottom: 2px;}
    .navbar .navbar-nav .open .dropdown-submenu .dropdown-menu > li > a{padding-left: 25px;}
    .navbar-default .navbar-nav .open .dropdown-menu .dropdown-submenu ul{background-color:#fff;}
    .navbar-inverse .navbar-nav .open .dropdown-menu .dropdown-submenu ul{background-color:#fff;}
} /* END New 2nd-level Dropdown CSS */

CSS 完成了 99%。现在我们只需要一点 Javascript 就可以带我们冲过终点线。

// Make Dropdown Submenus possible
$('.dropdown-submenu a.dropdown-submenu-toggle').on("click", function(e){
    $('.dropdown-submenu ul').removeAttr('style');
    $(this).next('ul').toggle();
    e.stopPropagation();
    e.preventDefault();
});
// Clear Submenu Dropdowns on hidden event
$('#bs-navbar-collapse-1').on('hidden.bs.dropdown', function () {
    $('.navbar-nav .dropdown-submenu ul.dropdown-menu').removeAttr('style');
});

差不多就这些了。在 http://demo.jdmdigital.co/wp-bootstrap-navwalker-multilevel/ and wrote a little article 做了一些可下载的现场演示，关于在使用 WordPress 菜单系统时使用相同的代码在 Bootstrap 菜单中启用此功能。

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