text: var myBirthTime = new Date(1985, 04, 26, 12, 30);
  function updateParagraph() {
      var now = new Date();
      var seconds = (now.getTime() - myBirthTime.getTime()) / 1000;
      document.getElementById('birth-time').innerText = '生まれてから' + seconds + '秒経過。';
  }
  setInterval(updateParagraph, 50);