多级引导菜单仅显示第一级

Question

我试图用引导程序3创建一个多层菜单，但无法让它工作，而且对引导程序的知识也不足以找出原因。

标记是

<div class="dropdown">
  <a role="button" data-toggle="dropdown" class="btn btn-primary" data-target="" href="">Y<span class="caret"></span></a>
  <ul class="dropdown-menu multi-level" role="menu" aria-labelledby="dropdownMenu">
    <li class="dropdown-submenu">
        <a href="#" tabindex="-1">foo</a>         
        <ul class="dropdown-menu">
            <li>
              <a href="">bar</a>
            </li>
        </ul>
    </li>
  </ul>
</div>

css和js如下所示

<link href="//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">

<script src="//netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>

我的期望是，当我打开第一个菜单("Y")时，我可以看到一个新的菜单项"foo“，它可以打开以显示最后一个菜单项"bar”。

代码是基于我找到这里的一个例子

Answer 1

这段代码片段中的CSS似乎完成了关于多级下拉列表的所有操作。请参阅下面的工作片段：

​

.dropdown-submenu {
  position: relative;
}

.dropdown-submenu>.dropdown-menu {
  top: 0;
  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: 0;
  height: 0;
  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;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<div class="dropdown">
  <a role="button" data-toggle="dropdown" class="btn btn-primary" data-target="" href="">Y<span class="caret"></span></a>
  <ul class="dropdown-menu multi-level" role="menu" aria-labelledby="dropdownMenu">
    <li class="dropdown-submenu">
      <a href="#" tabindex="-1">foo</a>
      <ul class="dropdown-menu">
        <li>
          <a href="">bar</a>
        </li>
      </ul>
    </li>
  </ul>
</div>

​

Answer 2

在例句之后，您应该尝试复制css样式：

.dropdown-submenu {
    position: relative;
}

.dropdown-submenu>.dropdown-menu {
    top: 0;
    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: 0;
    height: 0;
    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;
}

如果你把它们加进去，它会起作用的。如果你能成功的话，请告诉我们！)

Answer 3

这样就行了

​

<!DOCTYPE html>
<html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<style>
.dropdown-submenu {
    position: relative;
}

.dropdown-submenu .dropdown-menu {
    top: 0;
    left: 100%;
    margin-top: -1px;
}
</style>
</head>
<body>
   
<div class="container">                                      
  <div class="dropdown">
    <button class="btn btn-primary dropdown-toggle" type="button" data-toggle="dropdown">Y
    <span class="caret"></span></button>
    <ul class="dropdown-menu">
      <li class="dropdown-submenu">
        <a class="test" tabindex="-1" href="#">Foo <span class="caret"></span></a>
        <ul class="dropdown-menu">
          <li><a tabindex="-1" href="#">Bar</a></li>
            </ul>
          </li>
        </ul>
      </li>
    </ul>
  </div>
</div>


<script>
$(document).ready(function(){
  $('.dropdown-submenu a.test').on("click", function(e){
    $(this).next('ul').toggle();
    e.stopPropagation();
    e.preventDefault();
  });
});
</script>

</body>
</html>

​