mozilla-release/testing/web-platform/tests/webstorage/resources/local_change_item_iframe.html

<!DOCTYPE HTML>
<html>
  <body>
    <script>
        if (('localStorage' in window) && window.localStorage !== null){
            try {
                localStorage.setItem("name", "user1");
                localStorage.setItem("name", "user2");
            } catch (e) {
                parent.fail("setItem method is failed.");
            }
            localStorage.clear();
        } else {
            parent.fail("localStorage is not supported.");
        }
    </script>
  </body>
</html>