get-window-globals.js

{
  const iframe = document.createElement('iframe');
  iframe.src = 'data:text/html,';
  document.body.appendChild(iframe);
  const guestWin = iframe.contentWindow;
  const guestWinKeys = Object.keys(guestWin);
  const hostWinKeys = Object.keys(window);
  const diff = hostWinKeys.filter((key) => {
    return !guestWinKeys.includes(key); 
  }).sort();
  document.body.removeChild(iframe);
  diff;
}