JSFiddle - React, Tailwind, and code Playground

HTML

<p id="result"></p>
<button id="btn">Stop</button>

JavaScript

var stop = false;
var obj = document.getElementById("btn").addEventListener("click", function(){
    stop = true;
});

var interval;
function loop(){
    var result = document.getElementById("result");
    if(!stop){
        result.innerHTML = "Running...";
    }else{
        clearInterval(interval);
        result.innerHTML = "Stopped...";
    }
}
interval = setInterval(loop, 500);