JSFiddle - React, Tailwind, and code Playground

by Santosh Thakur

HTML

<span id="timer"></span>

JavaScript

document.getElementById('timer').innerHTML = 03 + ":" + 00
startTimer();

function startTimer() {
  var presentTime = document.getElementById('timer').innerHTML;
  var timeArray = presentTime.split(/[:]+/);
  var m = timeArray[0];
  var s = checkSecond((timeArray[1] - 1));
  if (s == 59) {
    m = m - 1
  }
  document.getElementById('timer').innerHTML = m + ":" + s;
  setTimeout(startTimer, 1000);
}

function checkSecond(sec) {
  if (sec < 10 && sec >= 0) {
    sec = "0" + sec
  }
  if (sec < 0) {
    sec = "59"
  }
  return sec;
}