countdown.js

const Countdown = (() => {

    let nextMidnight = new Date();
    nextMidnight.setHours(24,0,0,0);
  
    const getRemainingTime = () => {
      let now = new Date();
      let time = (nextMidnight.getTime() - now.getTime())/1000;   
      if(time < 0) {
        nextMidnight = new Date();
        nextMidnight.setHours(24,0,0,0); 
        return getRemainingTime();
      }
      return time;
    }
    
    const parseTime = (time) => {
      const hours = Math.floor(time/3600);
      let rest = time-(hours*3600);
      const minutes = Math.floor(rest/60);
      rest = rest-(minutes*60);
      const seconds = Math.floor(rest);
      const milliseconds = (rest-seconds)*1000;
      return [hours, minutes, seconds, milliseconds];
    };
    
    const formatTime = (parsedTime) => {
        return '<span class="hours">' + parsedTime[0] + '</span><span class="hSep">:</span><span class="minutes">' + ("0" + parsedTime[1]).slice(-2) + '</span><span class="mSep">:</span><span class="seconds">' + ("0" + parsedTime[2]).slice(-2) + '</span>';
    };
    
    const els = [];
    let timeout;
    
    return (el) => {
      els.push(el);
      
      if(!timeout) {
        const refresh = () => {
          const parsedTime = parseTime(getRemainingTime());
          const formattedTimes = formatTime(parsedTime);
          
          for(let i = 0, iend = els.length; i < iend; i++) {
            els[i].innerHTML = formattedTimes;
          }
          
          setTimeout(() => {
            refresh();
          }, parsedTime[3]);
        };
        refresh();
        
      }else 
        el.innerHTML = formatTime(parseTime(getRemainingTime()));
    };
  
  })();

Countdown(document.getElementById("countdownInfo"));