BS3 多级菜单

<div class="container">
    <div class="row">
        <h2>Multi level dropdown menu in Bootstrap 3</h2>
        <hr>
        <div class="dropdown">
            <a id="dLabel" role="button" data-toggle="dropdown" class="btn btn-primary" data-target="#" href="/page.html">
                Dropdown <span class="caret"></span>
            </a>
            <ul class="dropdown-menu multi-level" role="menu" aria-labelledby="dropdownMenu">
              <li><a href="#">Some action</a></li>
              <li><a href="#">Some other action</a></li>
              <li class="divider"></li>
              <li class="dropdown-submenu">
                <a tabindex="-1" href="#">Hover me for more options</a>
                <ul class="dropdown-menu">
                  <li><a tabindex="-1" href="#">Second level</a></li>
                  <li class="dropdown-submenu">
                    <a href="#">Even More..</a>
                    <ul class="dropdown-menu">
                        <li><a href="#">3rd level</a></li>
                        <li><a href="#">3rd level</a></li>
                    </ul>
                  </li>
                  <li><a href="#">Second level</a></li>
                  <li><a href="#">Second level</a></li>
                </ul>
              </li>
            </ul>
        </div>
    </div>
</div>  

.dropdown-submenu {
    position: relative;
}

.dropdown-submenu>.dropdown-menu {
    top:;
    left: 100%;
    margin-top: -6px;
    margin-left: -1px;
    -webkit-border-radius: 0 6px 6px 6px;
    -moz-border-radius: 0 6px 6px;
    border-radius: 0 6px 6px 6px;
}

.dropdown-submenu:hover>.dropdown-menu {
    display: block;
}

.dropdown-submenu>a:after {
    display: block;
    content: " ";
    float: right;
    width:;
    height:;
    border-color: transparent;
    border-style: solid;
    border-width: 5px 0 5px 5px;
    border-left-color: #ccc;
    margin-top: 5px;
    margin-right: -10px;
}

.dropdown-submenu:hover>a:after {
    border-left-color: #fff;
}

.dropdown-submenu.pull-left {
    float: none;
}

.dropdown-submenu.pull-left>.dropdown-menu {
    left: -100%;
    margin-left: 10px;
    -webkit-border-radius: 6px 0 6px 6px;
    -moz-border-radius: 6px 0 6px 6px;
    border-radius: 6px 0 6px 6px;
}

不需要额外的js,引入BS3,可以实现 多级的下拉菜单: