function init() {
  timeDisplay = document.createTextNode("");
  document.getElementById("clock").appendChild (timeDisplay);
}

function updateClock() {
  var currentTime = new Date();
  var currentHours = currentTime.getHours();
  var currentMinutes = currentTime.getMinutes();
  var currentSeconds = currentTime.getSeconds();
  currentMinutes = (currentMinutes < 10 ? "0" : "") + currentMinutes;
  currentSeconds = (currentSeconds < 10 ? "0" : "") + currentSeconds;
  var timeOfDay = (currentHours < 12) ? "am" : "pm";
  currentHours = (currentHours > 12) ? currentHours - 12 : currentHours;
  currentHours = (currentHours == 0) ? 12 : currentHours;
  var currentTimeString = "Current time: " + currentHours + ":" + currentMinutes + ":" + currentSeconds + " " + timeOfDay + " (GMT)";
  document.getElementById("clock").firstChild.nodeValue = currentTimeString;
}