unload-with-beacon.html

Enable keyboard shortcuts

<!DOCTYPE html>

<script>

  // When told, register an unload handler that will trigger a beacon to the

  // URL given by the sender of the message.

  window.addEventListener('message', e => {

      var url = e.data;

      window.addEventListener('unload', () => {

          navigator.sendBeacon(url, 'blah');

});

      window.parent.postMessage('navigate-away', '*');

});

</script>