<!DOCTYPE HTML>
<html lang="ru">
<head>
<meta charset="utf-8">
<title>jQuery loaded</title>
<script src='http://code.jquery.com/jquery-1.9.1.js'></script>
<script>
jQuery(function (f) {
f('h1>span').html(jQuery === f);
});
</script>
</head>
<body>
<h1>jQuery loaded, jQuery === f -
<span></span>
</h1>
</body>
</html>
В Joomla вставляйте в шаблон так
<script src='http://code.jquery.com/jquery-1.9.1.js'></script>
<jdoc:include type="head" />