The following code shows how to create button group from button and span.
<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-1.8.3.js'></script>
<link rel="stylesheet" type="text/css"
href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.1.1/css/bootstrap-combined.min.css">
<script type='text/javascript'
src="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.1.1/js/bootstrap.min.js"></script>
<script type='text/javascript'>
$(window).load(function(){<!--from ww w .j a va 2s . c o m-->
$('#action-btn').click(function(){
console.log("Do Something");
});
});
</script>
</head>
<body style='margin:30px'>
<div class="btn-group">
<button id="action-btn" class="btn btn-success">Recommend</button>
<span class="btn btn-success dropdown-toggle" data-toggle="dropdown">></span>
<ul class="dropdown-menu">
<li><a href="#">Recoemmend me</a></li>
<li><a href="#">Post to wall</a></li>
</ul>
</div>
</body>
</html>