bootstrap中的模态框（modal），不同于Tooltips，模态框以弹出对话框的形式出现，具有最小和最实用的功能集。
务必将模态框的 HTML 代码放在文档的最高层级内（也就是说，尽量作为 body 标签的直接子元素），以避免其他组件影响模态框的展现或功能。
默认的modal示例：
<!DOCTYPE html> <html lang="zh-CN"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <title>Bootstrap Modal</title> <link rel="stylesheet" href="http://cdn.bootcss.com/bootstrap/3.3.5/css/bootstrap.min.css"> </head> <body> <button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal"> Launch demo modal </button> <div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel"> <div class="modal-dialog" role="document"> <div class="modal-content"> <div class="modal-header"> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> <h4 class="modal-title" id="myModalLabel">Modal title</h4> </div> <div class="modal-body"> <p>One fine body…</p> </div> <div class="modal-footer"> <button type="button" class="btn btn-default" data-dismiss="modal">Close</button> <button type="button" class="btn btn-primary">Save</button> </div> </div> </div> </div> <script src="http://cdn.bootcss.com/jquery/1.11.3/jquery.min.js"></script> <script src="http://cdn.bootcss.com/bootstrap/3.3.5/js/bootstrap.min.js"></script> </body> </html>