JSFiddle - React, Tailwind, and code Playground

HTML

<span id="hours"></span>:<span id="minutes"></span>:<span id="seconds"></span>

JavaScript

(function() {
    var second = 1;
    var minute = second * 60;
    var hour = minute * 60;
    
    
    function beginCountdown(hours) {
        var seconds = (hours * hour);
        
        function countdownLoop() {
            var hoursRemaining = Math.floor((seconds / 60) / 60);
            var minutesRemaining = (Math.floor(seconds / 60) % 60);
            var secondsRemaining = (seconds % 60);
                    
            if (minutesRemaining < 10) {
                minutesRemaining = "0" + minutesRemaining;
            }
            
            if (secondsRemaining < 10) {
                secondsRemaining = "0" + secondsRemaining;
            }
            
            document.getElementById('hours').innerHTML = hoursRemaining;
            document.getElementById('minutes').innerHTML = minutesRemaining;
            document.getElementById('seconds').innerHTML = secondsRemaining;
            seconds--;
            if (seconds > -1) {
                setTimeout(function(){countdownLoop();}, 1000);
            }
            if (seconds <= 0) {
                seconds = (hours * hour);
            }
        }
        countdownLoop();
    }
    beginCountdown(3);
})();