twitter-bootstrap-3 - 下拉菜单中下拉切换类的用途是什么

Question

请帮助我了解下拉菜单中“下拉切换”类的使用。在下面的代码中，我删除了“下拉切换”类。没有这个下拉菜单也可以正常工作。那么这个类有什么用。

<div class="container-fluid">
  <h1>Hello, world!</h1>
  <div class="dropdown">
        <button type="button" class="btn btn-info" data-toggle="dropdown">MENU</button>
        <ul class="dropdown-menu">
          <li>ITEM-1</li>
          <li>ITEM-1</li>
          <li>ITEM-1</li>
          <li>ITEM-1</li>

        </ul>  

</div>

标签： twitter-bootstrap-3

Answer 1

该类dropdown-toggle将outline: 0;on添加:focus到按钮上，因此当您单击该按钮时，它将没有“活动”元素的周围蓝色​​边框。

查看下面的示例：

<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>

<div class="container">
  <h2>Dropdowns</h2>
  <p>The .divider class is used to separate links inside the dropdown menu with a thin horizontal line:</p>
  <div class="dropdown">
    <button class="btn btn-default dropdown-toggle" type="button" data-toggle="dropdown">Tutorials - no border
      <span class="caret"></span></button>
    <ul class="dropdown-menu">
      <li><a href="#">HTML</a></li>
      <li><a href="#">CSS</a></li>
      <li><a href="#">JavaScript</a></li>
      <li class="divider"></li>
      <li><a href="#">About Us</a></li>
    </ul>
  </div>
</div>

<div class="container">
  <h2>Dropdowns</h2>
  <p>The .divider class is used to separate links inside the dropdown menu with a thin horizontal line:</p>
  <div class="dropdown">
    <button class="btn btn-default" type="button" data-toggle="dropdown">Tutorials - with border
      <span class="caret"></span></button>
    <ul class="dropdown-menu">
      <li><a href="#">HTML</a></li>
      <li><a href="#">CSS</a></li>
      <li><a href="#">JavaScript</a></li>
      <li class="divider"></li>
      <li><a href="#">About Us</a></li>
    </ul>
  </div>
</div>