function clock() {
  var curDateTime = new Date()
  var curHour = curDateTime.getHours() 
     + curDateTime.getTimezoneOffset()/60
  if (curHour > 24)  curHour -= 24
  if (curHour < 0) curHour += 24
  var curMin = curDateTime.getMinutes()
  var curSec = curDateTime.getSeconds()
  var curTime = 
    ((curHour < 10) ? "0" : "") + curHour + ":" 
    + ((curMin < 10) ? "0" : "") + curMin + ":" 
    + ((curSec < 10) ? "0" : "") + curSec 
  document.clock.display.value = curTime + " GMT";
  timerID = setTimeout('clock()', 1000);
}

window.onLoad = clock();