http://v3.bootcss.com/components/#btn-dropdowns
mark
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<link rel="stylesheet" href="css/bootstrap.min.css">
</head>
<body>
<div class="container">
<!--單按鈕下拉菜單-->
<div class="btn-group">
<button type="button" class="btn btn-info dropdown-toggle" data-toggle="dropdown">
按鈕式下拉菜單
<span class="caret"></span>
</button>
<ul class="dropdown-menu" role="menu">
<li><a href="#">1</a> </li>
<li><a href="#">2</a> </li>
<li><a href="#">3</a> </li>
<li><a href="#">4</a> </li>
</ul>
</div>
<!--分裂式下拉菜單，只需將按鈕和向下的箭頭拆開，其實就是用兩個按鈕組合而成-->
<div class="btn-group">
<button type="button" class="btn btn-info" data-toggle="dropdown">
分裂式下拉菜單
</button>
<button type="button" class="btn btn-info dropdown-toggle" data-toggle="dropdown">
<span class="caret"></span>
</button>
<ul class="dropdown-menu" role="menu">
<li><a href="#">1</a> </li>
<li><a href="#">2</a> </li>
<li><a href="#">3</a> </li>
<li><a href="#">4</a> </li>
</ul>
</div>
<br>
<!--箭頭向上的下拉菜單，在外層div添加dropup即可-->
<div class="btn-group dropup">
<button type="button" class="btn btn-info" data-toggle="dropdown">
分裂式下拉菜單
</button>
<button type="button" class="btn btn-info dropdown-toggle" data-toggle="dropdown">
<span class="caret"></span>
</button>
<ul class="dropdown-menu" role="menu">
<li><a href="#">1</a> </li>
<li><a href="#">2</a> </li>
<li><a href="#">3</a> </li>
<li><a href="#">4</a> </li>
</ul>
</div>
</div>
<script src="js/jquery-2.1.4.min.js"></script>
<script src="js/bootstrap.min.js"></script>
</body>
</html>
