add keydown to whole page javascript code example

Example 1: keydown events

document.addEventListener('keydown', logKey);

function logKey(e) {
  log.textContent += ` ${e.code}`;
}

Example 2: event listener for keydown

eventTarget.addEventListener("keydown", event => {
  if (event.isComposing || event.keyCode === 229) {
    return;
  }
  // do something
});