this is how i do it…
iFrame HTML code:
<!doctype html>
Javascript code for front end:
//javascript page code for html iframe interaction
// when a message is received from the HTML Component
$w("#iFrameID").onMessage((results) => {
let googleAccoutInfo = results.data;
//string values for each item
let gUserId = results.data.userId;
let firstName = results.data.firstName;
let lastName = results.data.lastName;
let fullName = results.data.fullName;
let unformattedUserEmail = results.data.userEmail;
let idToken = results.data.idToken;
console.log(gUserId);
console.log(firstName);
console.log(lastName);
console.log(fullName);
console.log(unformattedUserEmail);
console.log(idToken);
//proceed to start session or register user with above user details