JSFiddle - React, Tailwind, and code Playground

HTML

<span id="minutes"></span>
<span id="seconds"></span>
<a href="#" id="start">Start</a>
<a href="#" id="stop">Stop</a>
<a href="#" id="pause">Pause</a>
<a href="#" id="resume">Resume</a>

JavaScript

var sec = 0;
var intPointer = null; 

function pad(val) {
    return val > 9 ? val : "0" + val;
}
function start() {
    clearInterval(intPointer);
    intPointer = setInterval(function() {
        var secondsI = pad(++sec % 60);
        var minutesI = pad(parseInt(sec / 60, 10));
        document.getElementById("seconds").innerHTML = secondsI;
        document.getElementById("minutes").innerHTML = minutesI;
    }, 1000);
}

window.onload = function() {
    document.getElementById('start').onclick = function(e) {
        sec = 0;
        document.getElementById("seconds").innerHTML = "00";
        document.getElementById("minutes").innerHTML = "00";
        start();
    };
    document.getElementById('stop').onclick = function(e) {
        sec = 0;
        document.getElementById("seconds").innerHTML = "00";
        document.getElementById("minutes").innerHTML = "00";
        clearInterval(intPointer);
    };
    document.getElementById('pause').onclick = function(e) {
        clearInterval(intPointer);
    };
    document.getElementById('resume').onclick = function(e) {
        start();
    };
    
    start();
}