引导程序下拉菜单中的dropdown-toggle类的目的是什么? [英] What's the purpose of dropdown-toggle class in bootstrap dropdowns?

问题描述

在<button>元素上应用或不应用dropdown-toggle引导类的情况下，下拉菜单都可以完美地工作，那么为什么要首先使用它?

Dropdown menus work perfectly with or without the dropdown-toggle bootstrap class being applied to <button> element,so why use it in the first place?

推荐答案

dropdown-toggle类将:focus上的outline: 0;添加到按钮上，因此当您单击按钮时，它将没有周围的蓝色边框活动"元素的内容.

The dropdown-toggle class adds the outline: 0; on :focus to the button, so when you click on the button it will not have the surrounding blue border of the "active" element.

检查接下来的两个botton:

Check the next two bottons:

<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>

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