<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css">
<script src="https://libs.baidu.com/jquery/2.1.4/jquery.min.js"></script>
<script src="https://apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<style>
.caret.caret-up { border-top-width: 0;
border-bottom: 4px solid #fff;
}
</style>
</head>
<body>
<div class="container">
<h2>Change the caret symbol on dropdown</h2>
<div class="dropdown">
<button class="btn btn-primary dropdown-toggle" type="button" data-toggle="dropdown">Dropdown
<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>
$(document).ready(function(){ $(".dropdown").on("hide.bs.dropdown", function(){ $(".btn").html('Dropdown <span class="caret"></span>'); });
$(".dropdown").on("show.bs.dropdown", function(){ $(".btn").html('Dropdown <span class="caret caret-up"></span>'); });
});
</script>
</body>
</html>