(function () {
  var clk = document.getElementById('clock');
  var days   = ['SUN','MON','TUE','WED','THU','FRI','SAT'];
  var months = ['JAN','FEB','MAR','APR','MAY','JUN','JUL','AUG','SEP','OCT','NOV','DEC'];
  function tick() {
    var d = new Date();
    var date = days[d.getDay()] + ' ' + months[d.getMonth()] + ' '
             + String(d.getDate()).padStart(2, '0');
    var time = String(d.getHours()).padStart(2,'0')   + ':'
             + String(d.getMinutes()).padStart(2,'0') + ':'
             + String(d.getSeconds()).padStart(2,'0');
    clk.textContent = date + '  ' + time;
  }
  tick();
  setInterval(tick, 1000);
}());