JSFiddle - React, Tailwind, and code Playground

HTML

<button onclick="myObject.stop()">stop</button>

<script type="text/javascript">
var i = 0;

function myFunction() {
  i++;
  console.log(i);
}

var interval = null;

interval = setInterval(function() {
  myFunction();
}, 1000);

myObject = {
  stop: function() {
    console.log("stopping");
    clearInterval(interval);
  }
};
</script>