源代码 ：
点击运行
<!DOCTYPE html> <html> <head> <title>Bootstrap 实例</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/css/bootstrap.min.css"> <script src="https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script> <script src="https://cdn.staticfile.org/popper.js/1.15.0/umd/popper.min.js"></script> <script src="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/js/bootstrap.min.js"></script> </head> <body> <div class="container"> <h2>下拉菜单中</h2> <p>.dropdown-header 类用于在下拉菜单中添加标题：</p> <div class="dropdown"> <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown"> Dropdown button </button> <div class="dropdown-menu"> <h5 class="dropdown-header">Dropdown header</h5> <a class="dropdown-item" href="#">Link 1</a> <a class="dropdown-item" href="#">Link 2</a> <a class="dropdown-item" href="#">Link 3</a> <h5 class="dropdown-header">Dropdown header</h5> <a class="dropdown-item" href="#">Another link</a> </div> </div> </div> </body> </html>
运行结果