<!DOCTYPE html>
<html>
<body style="background-color: rgb(255, 255, 255);">
  <div id='root'>
    <div id='a'>
      <div id='b'>
      </div>
    </div>
  </div>

  <script>
    var b = document.querySelector('#b');

    console.log('b.parentNode: ' + b.parentNode);

    document.body.removeChild(document.body.firstElementChild);
    console.log('after remove child');
    console.log('b.parentNode: ' + b.parentNode);

    gc();
    console.log('after gc()');
    console.log('b.parentNode: ' + b.parentNode);
  </script>
</body>
</html>