var timerID = null;
var timerRunning = false;

function stopclock ()
{
  if(timerRunning)
    clearTimeout(timerID);
  timerRunning = false;
}

function showtime ()
{
  var now = new Date();
  var hours = now.getHours();
  var minutes = now.getMinutes();
  var seconds = now.getSeconds();
  var timeValue =hours;
  if (timeValue == "0")
    timeValue = 12;
  timeValue += ((minutes < 10) ? ":0" : ":") + minutes;
  timeValue += ((seconds < 10) ? ":0" : ":") + seconds;
  document.getElementById("face").innerHTML = timeValue;
  timerID = setTimeout("showtime()",1000);
  timerRunning = true;
}
function startclock()
{
  stopclock();
  showtime();
}