log in/out with gmail

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" name="google-signin-client_id" content="503693956193-qaq9k02vibebr4la22ta1ggsutbmj5ts.apps.googleusercontent.com">
    <title>Title</title>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script src="https://apis.google.com/js/platform.js" async defer></script>

</head>
<body>
<div class="g-signin2" data-onsuccess="onSignIn"></div>
<a href="#" onclick="signOut()">Sign out</a>
<script>
    function onSignIn(googleUser) {
        alert('fwef')
  var profile = googleUser.getBasicProfile();
  alert('ID: ' + profile.getId()); // Do not send to your backend! Use an ID token instead.
  alert('Name: ' + profile.getName());
  alert('Image URL: ' + profile.getImageUrl());
  alert('Email: ' + profile.getEmail()); // This is null if the 'email' scope is not present.

    }

     function signOut() {
         alert('1')
    var auth2 = gapi.auth2.getAuthInstance();
         alert(2)
    auth2.signOut().then(function () {
      alert('User signed out.');
    });
  }

</script>

</body>
</html>