How to make a 3-level collapsing menu in Bootstrap

I am trying to make a 3-level collapsing navbar menu for Bootstrap, but I can't open the third level.

This is the two level menu which I have:

<link href="https://stackpath.bootstrapcdn.com/twitter-bootstrap/2.3.2/css/bootstrap-combined.min.css" rel="stylesheet"/>
<div class="navbar navbar-fixed-top">
  <div class="navbar-inner">
    <div class="container">
      <a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </a>

      <div class="nav-collapse">
        <ul class="nav">
          <a class="brand" href="#">Present Ideas</a>
          <li class="active"><a href="#">Home</a></li>
          <li><a href="#">Blog</a></li>
          <li><a href="#">About</a></li>
          <li><a href="#">Help</a></li>
          <li class="dropdown" id="accountmenu">
            <a class="dropdown-toggle" data-toggle="dropdown" href="#">Account Settings<b class="caret"></b></a>
            <ul class="dropdown-menu">
              <li><a href="#">Login</a></li>
              <li><a href="#">Register</a></li>
              <li class="divider"></li>
              <li><a href="#">Logout</a></li>
            </ul>
          </li>
        </ul>
        <ul class="nav pull-right">

        </ul>
      </div>
      <!--/.nav-collapse -->
    </div>
  </div>
</div>

I thought something like this would work:

<link href="https://stackpath.bootstrapcdn.com/twitter-bootstrap/2.3.2/css/bootstrap-combined.min.css" rel="stylesheet"/>
<div class="navbar navbar-fixed-top">
  <div class="navbar-inner">
    <div class="container">
      <a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </a>

      <div class="nav-collapse">
        <ul class="nav">
          <li class="active"><a href="#">Home</a></li>
          <li><a href="#">Blog</a></li>
          <li><a href="#">About</a></li>
          <li><a href="#">Help</a></li>
          <li class="dropdown" id="accountmenu">
            <a class="dropdown-toggle" data-toggle="dropdown" href="#">Account Settings<b class="caret"></b></a>
            <ul class="dropdown-menu">
              <li><a href="#">Login</a></li>
              <li class="item-148 dropdown parent">
                <a href="/about/learn-more">Learn more&nbsp;<b class="caret-right"></b></a>
                <ul class="dropdown-menu">
                  <li class="item-149"><a href="/about/learn-more/the-software">The Software</a></li>
                  <li class="item-150"><a href="/about/learn-more/the-project">The Project</a></li>
                  <li class="item-151"><a href="/about/learn-more/the-leadership">The Leadership</a></li>
                  <li class="item-152"><a href="/about/learn-more/open-source-matters">Open Source Matters</a></li>
                </ul>
              </li>
              <li class="divider"></li>
              <li><a href="#">Logout</a></li>
            </ul>
          </li>
        </ul>
        <ul class="nav pull-right">

        </ul>
      </div>
      <!--/.nav-collapse -->
    </div>
  </div>
</div>

But that's not working.

回答1:

Bootstrap 2.3.x and later supports the dropdown-submenu..

<ul class="dropdown-menu">
            <li><a href="#">Login</a></li>
            <li class="dropdown-submenu">
                <a tabindex="-1" href="#">More options</a>
                <ul class="dropdown-menu">
                    <li><a tabindex="-1" href="#">Second level</a></li>
                    <li><a href="#">Second level</a></li>
                    <li><a href="#">Second level</a></li>
                </ul>
            </li>
            <li><a href="#">Logout</a></li>
</ul>

Working demo on Bootply.com

回答2:

Bootstrap 3 dropped native support for nested collapsing menus, but there's a way to re-enable it with a 3rd party script. It's called SmartMenus. It means adding three new resources to your page, but it seamlessly supports Bootstrap 3.x with multiple levels of menus for nested <ul>/<li> elements with class="dropdown-menu". It automatically displays the proper caret indicator as well.

<head>
   ...
   <script src=".../jquery.smartmenus.min.js"></script>
   <script src=".../jquery.smartmenus.bootstrap.min.js"></script>
   ...
   <link rel="stylesheet" href=".../jquery.smartmenus.bootstrap.min.css"/>
   ...
</head>

Here's a demo page: http://vadikom.github.io/smartmenus/src/demo/bootstrap-navbar-fixed-top.html