HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>fullscreenElement null</title>
</head>
<body>
  <pre id="out"></pre>
  <script>
    document.getElementById("out").textContent =
      String(document.fullscreenElement) + "\n" +
      "active? " + (document.fullscreenElement !== null);
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

fullscreenElement — read null (Try It)