Bootstrap 下拉列表

下拉菜单是可切换的上下文菜单，用于以列表格式显示链接。它使用户可以从预定义的列表中选择一个值。可以使用下拉JavaScript插件使之具有交互性。

您必须将下拉菜单包装在class.dropdown中，以创建Bootstrap Dropdown。

Bootstrap下拉示例

 <!DOCTYPE html>
<html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
  
</head>
<body>
<div class="container">
  <h2>Dropdowns</h2>
  <p>The .dropdown class is used to indicate a dropdown menu.</p>
  <p>Use the .dropdown-menu class to actually build the dropdown menu.</p>
  <p>To open the dropdown menu, use a button or a link with a class of .dropdown-toggle and data-toggle="dropdown".</p>                                          
  <div class="dropdown">
    <button class="btn btn-primary dropdown-toggle" type="button" data-toggle="dropdown">Dropdown Example
    <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>
    </ul>
  </div>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
</body>
</html>

Bootstrap 下拉分隔符

class.divider 用于分隔下拉菜单中的链接:

参见以下示例:

<!DOCTYPE html>
<html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
 
</head>
<body>
<div class="container">
  <h2>Dropdowns</h2>
  <p>The .divider class is used to separate links inside the dropdown menu:</p>
  <div class="dropdown">
    <button class="btn btn-default dropdown-toggle" type="button" data-toggle="dropdown">Tutorials
    <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>
 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
 <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
</body>
</html>

Bootstrap下拉标题

class.dropdown-header 用于在下拉菜单中添加标题。

请参见以下示例:

<!DOCTYPE html>
<html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
 
</head>
<body>
<div class="container">
  <h2>Dropdowns</h2>
  <p>The .dropdown-header class is used to add headers inside the dropdown menu:</p>
  <div class="dropdown">
    <button class="btn btn-default dropdown-toggle" type="button" data-toggle="dropdown">Tutorials
    <span class="caret"></span></button>
    <ul class="dropdown-menu">
      <li class="dropdown-header">Dropdown header 1</li>
      <li><a href="#">HTML</a></li>
      <li><a href="#">CSS</a></li>
      <li><a href="#">JavaScript</a></li>
      <li class="divider"></li>
      <li class="dropdown-header">Dropdown header 2</li>
      <li><a href="#">About Us</a></li>
    </ul>
  </div>
</div>
 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
 <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
</body>
</html>

Bootstrap 下拉菜单: 禁用项

使用 class.disabled 禁用下拉菜单中的项。

请参见以下示例:

<!DOCTYPE html>
<html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
  
</head>
<body>
<div class="container">
  <h2>Dropdowns</h2>
  <p>Here, CSS is disable.</p>
  <div class="dropdown">
    <button class="btn btn-default dropdown-toggle" type="button" data-toggle="dropdown">Tutorials
    <span class="caret"></span></button>
    <ul class="dropdown-menu">
      <li><a href="#">HTML</a></li>
      <li class="disabled"><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>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
</body>
</html>

Bootstrap 4禁用和活动项目

要使某个项目处于活动状态，请使用.active类突出显示特定的下拉菜单项(活动项目以蓝色背景色显示)。

要禁用下拉菜单中的某个项目，您必须使用.disabled类(它会显示浅灰色的文本颜色和悬停时带有" no-parking-sign"的图标)。

示例:

<!DOCTYPE html>
<html>
<head>
  <title>Bootstrap Example</title>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.6/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
  <h2>Dropdowns Active and Disable Example</h2>
  <div class="dropdown">
    <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
      Dropdown button
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Normal</a>
      <a class="dropdown-item active" href="#">Active</a>
      <a class="dropdown-item disabled" href="#">Disabled</a>
    </div>
  </div>
</div>
</body>
</html>

下拉位置

用于放置下拉项。默认情况下，下拉菜单位于左侧。您可以通过将.dropdown-menu-right类添加到具有.dropdown-menu的元素来使下拉列表右对齐。

示例:

<!DOCTYPE html>
<html>
<head>
  <title>Bootstrap Example</title>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.6/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
  <h2>Right Aligned Dropdowns</h2>
  <div class="dropdown">
    <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
      Dropdown button
    </button>
    <div class="dropdown-menu dropdown-menu-right">
      <a class="dropdown-item" href="#">Link 1</a>
      <a class="dropdown-item" href="#">Link 2</a>
      <a class="dropdown-item" href="#">Link 3</a>
    </div>
  </div>
</div>
</body>
</html>

Bootstrap 4 Dropup

如果您希望下拉菜单向上扩展而不是向下扩展，请更改

class ="dropdown"到" dropup"的元素:

示例:

<!DOCTYPE html>
<html>
<head>
  <title>Bootstrap Example</title>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.6/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>
</head>
<body>
<br>
<div class="container">
  <h2>Dropup Example</h2>
  <p>The .dropup class makes the dropdown menu expand upwards instead of downwards:</p>
  <div class="dropup">
    <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
      Dropup button
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Link 1</a>
      <a class="dropdown-item" href="#">Link 2</a>
    </div>
  </div>
</div>
</body>
</html>

拆分按钮下拉列表

它用于将下拉列表显示为拆分按钮。在这里，我们使用所有上下文类。

示例:

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Bootstrap Example</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.6/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
  <h2>Dropdown Split Buttons Example</h2>
  <div class="btn-group">
    <button type="button" class="btn btn-primary">Primary</button>
    <button type="button" class="btn btn-primary dropdown-toggle dropdown-toggle-split" data-toggle="dropdown">
      <span class="caret"></span>
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Link 1</a>
      <a class="dropdown-item" href="#">Link 2</a>
    </div>
  </div>
  
  <div class="btn-group">
    <button type="button" class="btn btn-secondary">Secondary</button>
    <button type="button" class="btn btn-secondary dropdown-toggle dropdown-toggle-split" data-toggle="dropdown">
      <span class="caret"></span>
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Link 1</a>
      <a class="dropdown-item" href="#">Link 2</a>
    </div>
  </div>
  <div class="btn-group">
    <button type="button" class="btn btn-success">Success</button>
    <button type="button" class="btn btn-success dropdown-toggle dropdown-toggle-split" data-toggle="dropdown">
      <span class="caret"></span>
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Link 1</a>
      <a class="dropdown-item" href="#">Link 2</a>
    </div>
  </div>
  <div class="btn-group">
    <button type="button" class="btn btn-info">Info</button>
    <button type="button" class="btn btn-info dropdown-toggle dropdown-toggle-split" data-toggle="dropdown">
      <span class="caret"></span>
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Link 1</a>
      <a class="dropdown-item" href="#">Link 2</a>
    </div>
  </div>
  <div class="btn-group">
    <button type="button" class="btn btn-warning">Warning</button>
    <button type="button" class="btn btn-warning dropdown-toggle dropdown-toggle-split" data-toggle="dropdown">
      <span class="caret"></span>
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Link 1</a>
      <a class="dropdown-item" href="#">Link 2</a>
    </div>
  </div>
  <div class="btn-group">
    <button type="button" class="btn btn-danger">Danger</button>
    <button type="button" class="btn btn-danger dropdown-toggle dropdown-toggle-split" data-toggle="dropdown">
      <span class="caret"></span>
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Link 1</a>
      <a class="dropdown-item" href="#">Link 2</a>
    </div>
  </div>
</div>
</body>
</html>

Bootstrap Wells

Bootstrap 位置