jam.js

function animation(span) {
   span.className = "turn";
   setTimeout(function() {
      span.className = "";
   }, 700);
}

function jam(){
   setInterval(function() {
      var waktu = new Date();
      var jam = document.getElementById('jam');
      var hours = waktu.getHours();
      var minutes = waktu.getMinutes();
      var seconds = waktu.getSeconds();

      if (waktu.getHours() < 10) {
         hours = '0' + waktu.getHours();
      }
      if (waktu.getMinutes() < 10) {
         minutes = '0' + waktu.getMinutes();
      }
      if (waktu.getSeconds() < 10) {
        seconds = '0' + waktu.getSeconds();
      }

      jam.innerHTML =  '<span>'+hours+'</span>'
                                  + '<span>'+minutes+'</span>'
                                  + '<span>'+seconds+'</span>';

      var spans = jam.getElementByTagName('span');
      animation(spans[2]);
      if (seconds == 0) animation(spans[1]);
      if (minutes == 0 && seconds == 0) animation(spans[0]);

   }, 1000);
}

jam();