In terms of loading order, what is happening in this script? Does the divLoading div tag finish loading before the jquery libraries finish loading? And, do the libraries start loading before the divLoading div tag is created on the users screen?
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.4.2.min.js"></script>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.9/jquery-ui.min.js"></script>
</head>
<body>
<div id="divLoading">loading...</div>
<img src="http://goes.gsfc.nasa.gov/pub/goes/060619_fulldisk_color.jpg" />
</body>
</html>
JS is blocking, so HTML parsing will pause while the scripts are loaded.