The following code shows how to show closable alert box.
<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-git2.js'></script>
<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'>
$(window).load(function(){<!--from w w w. ja va 2s . c om-->
$('#the-thing-that-opens-your-alert').click(function () {
$('#le-alert').addClass('in');
});
$('.close').click(function () {
$(this).parent().removeClass('in');
});
});
</script>
</head>
<body>
<a id="the-thing-that-opens-your-alert" href="#">Open my alert</a>
<div id="le-alert" class="alert alert-warn alert-block fade">
<button href="#" type="button" class="close">×</button>
<h4>Alert title</h4>
<p>Roses are red, violets are blue...</p>
</div>
</body>
</html>