JSFiddle - React, Tailwind, and code Playground

HTML

<script type="text/javascript">        
    var mins = 10;  //Set the number of minutes you need
    var secs = mins * 60;
    var currentSeconds = 0;
    var currentMinutes = 0;

    function Decrement() {
        currentMinutes = Math.floor(secs / 60);
        currentSeconds = secs % 60;
        if(currentSeconds <= 9) currentSeconds = "0" + currentSeconds;
        secs--;
        document.getElementById("timerText").innerHTML = currentMinutes + ":" + currentSeconds; //Set the element id you need the time put into.
    } 
</script>

<h1 id="title"> 
  START THE TIMER
</h1>

<h2 id="timerText">######</h2>

<button onclick="setInterval(Decrement, 1000)">GO!</button>