<div>Count: <span class="counter">0</span></div>
<button class="stop">Clear the timeout ...eh interval</button>
var counterVal = 0;
var intervalID = window.setInterval(function () {
  var el = document.querySelector(".counter");
  counterVal += 1;
  el.innerText = counterVal;
}, 1000);

document.querySelector(".stop").addEventListener("click", function () {
  window.clearTimeout(intervalID);
});

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