<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
  </head>
  <body>
    <form name="sampleform" action="https://test.com" method="POST">
      <input type="hidden" id="uid" name="am_authid">
      <input type="hidden" name="am_authpasswd" value="*****">
      <input type="hidden" name="am_authdomain_secid" value="item0">
      <input type="hidden" name="language" value="ja">
    </form>

    <SCRIPT language="JavaScript">
      const params = new URLSearchParams(window.location.search);
      const uid = params.get('uid');
      document.getElementById('uid').value = uid;
      document.sampleform.submit();
    </script>

  </body>
</html>
