How to protect a page from being accidentally closed in Google Chrome?

Question

JavaScript

Tried like this:

window.addEventListener('beforeunload', function() {
    event.preventDefault();
    confirm('Действительно закрыть приложение? Все данные будут потеряны!');
});

But alas, apparently it is necessary somehow differently. If not difficult, can someone provide a working example?

Answer 1

Thanks everyone, got it. It should turn out like this:

window.onbeforeunload = function() {
  return false;
};