javascript:
  startTime = #{@contest.start_time.present? ? @contest.start_time.to_i : "null"};
  pauseTime = #{@contest.pause_time.present? ? @contest.pause_time.to_i : "null"};
  function updateTime() {
    const displayTimeEl = document.getElementById('display-time');
    if (displayTimeEl) {
      if (startTime) {
        let s = Math.floor((Date.now() - 1000 * startTime) / 1000);
        if (pauseTime) s = Math.floor(pauseTime - startTime);
        let ss = s % 60;
        let mm = Math.floor(s / 60) % 60;
        let hh = Math.floor(s / 3600);
        displayTimeEl.innerHTML = `${hh < 10 ? `0${hh}` : hh}:${mm < 10 ? `0${mm}` : mm}:${ss < 10 ? `0${ss}` : ss}`;
        setTimeout(updateTime, 1000);
      } else {
        displayTimeEl.innerHTML = '00:00:00';
      }
    } else {
      setTimeout(updateTime, 20);
    }
  }
  setTimeout(updateTime, 1);