1. rel=noopener

    Ensure new browsing contexts are opened without a useful `window.opener`

  2. html element: area: `target="_blank"` implies `rel="noopener"` behavior

  3. html element: area: rel: noopener

  4. html element: a: `target="_blank"` implies `rel="noopener"` behavior

  5. html element: a: rel: noopener