getting keydown and up javascript code example

Example 1: javascript detect arrow key press

//detecting arrow key presses
document.addEventListener('keydown', function(e) {
    switch (e.keyCode) {
        case 37:
            alert('left');
            break;
        case 38:
           alert('up');
            break;
        case 39:
            alert('right');
            break;
        case 40:
            alert('down');
            break;
    }
});

Example 2: keydown events

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