function twoDigits(number){
    return (number.toString().length==1)? "0"+number : number
}

var localDate=new Date();
function clockStart() {
    var now = new Date();
    var ts = serverDate.getTime() - localDate.getTime() + now.getTime();
    var display = new Date(ts);
    var timeString=twoDigits(display.getHours())+":"+twoDigits(display.getMinutes())+":"+twoDigits(display.getSeconds());
    document.getElementById('clockfield').value = timeString;
    setTimeout("clockStart()", 500);
}