JSFiddle - React, Tailwind, and code Playground

HTML

<span id="placeholder"></span>
<button id="stop">Stop</button>
<button id="start">Start</button>

JavaScript

var _timeout = null;
var _itreator = 0;
var start = function () { 
    document.querySelector("#placeholder").innerHTML = _itreator;
    
    _timeout = setTimeout(function () {
        start(++_itreator);
    }, 1000); 
};

var stop = function () {
    clearTimeout(_timeout);
};

document.querySelector("#start").onclick = start;
document.querySelector("#stop").onclick = stop;