Event handler

event.preventdefault()

worker postmessage event = message

//squareworker.js

addEventListener("message", event => {
  postMessage(event.data * event.data);
});

let squareWorker = new Worker("code/squareworker.js");
squareWorker.addEventListener("message", event => {
  console.log("The worker responded:", event.data);
});
squareWorker.postMessage(10);
squareWorker.postMessage(24);

let bombTimer = setTimeout(() => {
  console.log("BOOM!");
}, 500);

if (Math.random() < 0.5) { // 50% chance
  console.log("Defused.");
  clearTimeout(bombTimer);
}

<textarea>Type something here...</textarea>
<script>
  let textarea = document.querySelector("textarea");
  let timeout;
  textarea.addEventListener("input", () => {
    clearTimeout(timeout);
    timeout = setTimeout(() => console.log("Typed!"), 500);
  });
</script>