Maintain Scroll Position after Asynchronous Postback

<script type="text/javascript">
    var xPos, yPos;
    var prm = Sys.WebForms.PageRequestManager.getInstance();
    prm.add_beginRequest(BeginRequestHandler);
    prm.add_endRequest(EndRequestHandler);
    function BeginRequestHandler(sender, args) {
        xPos = $get('scrollDiv').scrollLeft;
        yPos = $get('scrollDiv').scrollTop;
    }
    function EndRequestHandler(sender, args) {
        $get('scrollDiv').scrollLeft = xPos;
        $get('scrollDiv').scrollTop = yPos;
    }
</script>