The following code shows how to click to show button icon.
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css"
href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/css/bootstrap-combined.min.css">
<script type='text/javascript'
src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type='text/javascript'>
window.onload=function(){<!-- w w w . j ava 2s .c om-->
$(function() {
$('.btn').click(function() {
$(this).find('span').show();
});
});
}
</script>
</head>
<body style='margin:30px'>
<div class="btn">
<span style="display: none"><i class="icon-trash"></i></span> Button
</div>
<br />
</script>
</body>
</html>