var clock = 0;
function UpdateClock() {
    if(clock) {
       clearTimeout(clock);
       clock = 0;
    }

    document.getElementById('clock').innerHTML = GetTime();
    clock = setTimeout("UpdateClock()", 1000);
}
function StartClock() {
    clock = setTimeout("UpdateClock()", 500);
}

function GetTime(){

    var tDate = new Date();
   
    hour = ''+tDate.getHours();
    minutes = ''+tDate.getMinutes();
    seconds = ''+tDate.getSeconds();
    if(hour.length == 1){ hour = '0'+hour; }
    if(minutes.length == 1){ minutes = '0'+minutes; }
    if(seconds.length == 1){ seconds = '0'+seconds; }

    return hour+':'+minutes+':'+seconds;
}

function KillClock() {
    if(clock) {
       clearTimeout(clock);
       clock = 0;
    }
}