silent.html

<!doctype html>
<html>
<head>
  <meta charset="utf-8">
  <script src="https://cdn.auth0.com/js/auth0/8.8/auth0.min.js"></script>
  <script>
    var AUTH0_CLIENT_ID = '14MrUUfzDjKlVLGiTZVPdBciH3hJv31g';
    var AUTH0_DOMAIN = 'doman.auth0.com';

    if (!AUTH0_CLIENT_ID || !AUTH0_DOMAIN) {
      alert('Make sure to set the AUTH0_CLIENT_ID and AUTH0_DOMAIN variables in silent.html.');
    }

    var webAuth = new auth0.WebAuth({
      domain: AUTH0_DOMAIN,
      clientID: AUTH0_CLIENT_ID,
      scope: 'openid profile',
      responseType: 'token id_token',
      redirectUri: 'http://localhost:3000'
    });
  </script>
  <script>
    webAuth.parseHash(window.location.hash, function (err, response) {
      parent.postMessage(err || response, 'http://localhost:3000');
    });
  </script>
</head>
<body></body>
</html>