JSFiddle - React, Tailwind, and code Playground

HTML

<div id="timer"></div>

JavaScript

String.prototype.toHHMMSS = function () {
    var sec_num = parseInt(this, 10); // don't forget the second parm
    var hours   = Math.floor(sec_num / 3600);
    var minutes = Math.floor((sec_num - (hours * 3600)) / 60);
    var seconds = sec_num - (hours * 3600) - (minutes * 60);

    if (hours   < 10) {hours   = "0"+hours;}
    if (minutes < 10) {minutes = "0"+minutes;}
    if (seconds < 10) {seconds = "0"+seconds;}
    var time    = hours+':'+minutes+':'+seconds;
    return time;
}

var count ='62'; // it's 00:01:02
    count = count.toHHMMSS(); // remove this line to  check 

    var counter = setInterval(timer, 1000);
   
    function timer() {
  
        count--;
        if (count <= 0) {
            clearInterval(counter);         
            return;
        }
        
        $('#timer').html(count);
    }