如何在折叠的导航栏中默认打开 Bootstrap 3 下拉菜单 [英] How to make a Bootstrap 3 dropdown menu open by default when it is inside a collapsed navbar

问题描述

当我折叠的导航栏打开时，我试图让我的下拉菜单默认打开.这是一个 fiddle 来展示我目前的代码.

目前，如果您在折叠状态下单击导航栏，则会显示两个链接和一个下拉菜单.您必须再次单击以打开下拉菜单.

我的目标是在默认情况下打开下拉菜单并在折叠的导航栏打开时隐藏 a.dropdown-toggle 元素.当折叠的导航栏打开时，我希望它看起来如何:

• 链接
• 链接
• 下拉菜单
• 行动
• 另一个动作
• 这里还有别的东西
• 单独的链接
• 另外一个单独的链接

我的第一个想法是在 a.dropdown-toggle 上使用 display: none 但这只是隐藏了整个下拉菜单.希望有人可以提出一些建议.我对 jQuery 和 CSS 解决方案持开放态度.

我的标记:

<div class="container-fluid"><!-- 品牌和切换被分组以获得更好的移动显示--><div class="navbar-header"><button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1"><span class="sr-only">切换导航</span><span class="icon-bar"></span><span class="icon-bar"></span><span class="icon-bar"></span><a class="navbar-brand" href="#">Brand</a>

<!-- 收集导航链接、表单和其他用于切换的内容--><div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1"><ul class="nav navbar-nav"><li class="active"><a href="#">Link</a></li><li><a href="#">链接</a></li><li class="下拉菜单"><a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <span class="caret"></span></a><ul class="dropdown-menu" role="menu"><li><a href="#">动作</a></li><li><a href="#">另一个动作</a></li><li><a href="#">这里还有别的东西</a></li><li class="divider"></li><li><a href="#">分隔链接</a></li><li class="divider"></li><li><a href="#">一个单独的链接</a></li></div><!--/.navbar-collapse --></div><!--/.container-fluid --></nav>

解决方案

您可以为响应式移动显示添加 css 样式.将其粘贴到您的 css 文件中:

@media only screen and (max-width:480px){.下拉式菜单{显示:块；位置:静态；背景颜色:透明；边界:0 无；框阴影:无；边距顶部:0;位置:静态；宽度:100%；}.navbar-nav .dropdown-menu >立>一个，.navbar-nav .dropdown-menu .dropdown-header {填充:5px 15px 5px 25px;}.navbar-nav .dropdown-menu >立>一个{行高:20px；}.navbar-default .navbar-nav .dropdown-menu >立>一个{颜色:#777；}}

你可以在这里看到它的全部内容:Demo jsfiddle

希望有所帮助.

I'm trying to make my dropdown menu open by default when my collapsed navbar is opened. Here is a fiddle to show my code so far.

Currently, if you click on the navbar when it's in a collapsed state, two links and a dropdown menu are revealed. You have to click again to open the dropdown menu.

My aim is to make the dropdown menu open by default and hide the a.dropdown-toggle element when the collapsed navbar is opened. A visual of how I'd like it to look when the collapsed navbar is opened:

• Link
• Link
• Dropdown
• Action
• Another action
• Something else here
• Separated link
• One more separated link

My first thought was to use display: none on a.dropdown-toggle but that just hides the whole dropdown menu. Hoping someone can suggest something. I'm open to both jQuery and CSS solutions.

My markup:

<nav class="navbar navbar-default" role="navigation">
  <div class="container-fluid">
    <!-- Brand and toggle get grouped for better mobile display -->
    <div class="navbar-header">
      <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
        <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">
      <ul class="nav navbar-nav">
        <li class="active"><a href="#">Link</a></li>
        <li><a href="#">Link</a></li>
        <li class="dropdown">
          <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <span class="caret"></span></a>
          <ul class="dropdown-menu" role="menu">
            <li><a href="#">Action</a></li>
            <li><a href="#">Another action</a></li>
            <li><a href="#">Something else here</a></li>
            <li class="divider"></li>
            <li><a href="#">Separated link</a></li>
            <li class="divider"></li>
            <li><a href="#">One more separated link</a></li>
          </ul>
        </li>
      </ul>
    </div><!-- /.navbar-collapse -->
  </div><!-- /.container-fluid -->
</nav>

解决方案

You can add css style for responsive mobile display. paste it into your css file:

@media only screen and (max-width:480px){
    .dropdown-menu{
        display: block;
        position: static;
        background-color:transparent;
        border:0 none;
        box-shadow:none;
        margin-top:0;
        position:static;
        width:100%;
    }
    .navbar-nav .dropdown-menu > li > a, 
    .navbar-nav .dropdown-menu .dropdown-header {
        padding:5px 15px 5px 25px;
    }
    .navbar-nav .dropdown-menu > li > a{
        line-height:20px;
    }
    .navbar-default .navbar-nav .dropdown-menu > li > a{    
        color:#777;
    }
}

you can see it in its entirety here : Demo jsfiddle

hope that helps.

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