You don't need jquery to do that, just javascript. For example, you can do a timer using this:
<body onload="clock();">
<script type="text/javascript">
function clock() {
var now = new Date();
var outStr = now.getHours()+':'+now.getMinutes()+':'+now.getSeconds();
document.getElementById('clockDiv').innerHTML=outStr;
setTimeout('clock()',1000);
}
clock();
</script>
<div id="clockDiv"></div>
</body>
You can view a complete reference here: http://www.hunlock.com/blogs/Javascript_Dates-The_Complete_Reference