JavaScript

              
const clock = () => {
  const d = new Date();
  
  let year = d.getFullYear();
  let month = clockFormat(d.getMonth() + 1);
  let date = clockFormat(d.getDate());

  const weekday = ["SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT"];
  let day = weekday[d.getDay()];
  
  let hour = clockFormat(d.getHours());
  let min = clockFormat(d.getMinutes());
  let sec = clockFormat(d.getSeconds());

  let today = `${year}.${month}.${date} ${day}`;
  let time = `${hour}:${min}:${sec}`;

  document.querySelector(".clock-date").innerText = today;
  document.querySelector(".clock-time").innerText = time;
};

const clockFormat = (t) => {
  return String(t).padStart(2, '0');
};
clock();
setInterval(clock, 1000);