JSFiddle - React, Tailwind, and code Playground

HTML

<div class="timer"></div>

JavaScript

var minutes = 1;
var seconds = minutes * 60;

function convertIntToTime (num) {
    var mins = Math.floor(num/60);
    var secs = num % 60;
    var timerOutput = (mins < 10 ? "0" : "" ) + mins + ":" + (secs < 10 ? "0" : "" ) + secs;
    return(timerOutput);
}

var countdown = setInterval(function() {
    var current = convertIntToTime(seconds); // set the display of the time
    $('.timer').html(current); // place the display time in the div
    if(seconds == 0) { 
        clearInterval(countdown); // stop the time when there are no more seconds
    }
    seconds--; // subtract a second
}, 1000);