在bootstrap下拉列表中下拉切换类的目的是什么？

Question

无论是否将dropdown-togglebootstrap类应用于<button>元素,下拉菜单都可以正常工作,那么为什么要首先使用它呢？

Answer 1

本dropdown-toggle类添加outline: 0;上:focus的按钮,所以当你点击按钮,它不会有"活动"元素的周围蓝色边框.

检查下两个瓶子:

<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>