Oder ohne jquery:
HTML-Code:
<!doctype html>
<html>
<head>
<title></title>
<style type="text/css">
.box { height: 200px; width: 200px; background: #0F6; }
.script .box { display: none; }
</style>
</head>
<body>
<div class="box">
Ich bin Offen weil kein Javascript vorhanden ist.
</div>
<script type="text/javascript">
document.body.className += ' script';
</script>
</body>
</html>