handleUserAuth.js

import { auth } from "./firebaseConfig.js"; 
import { signInUserWithGoogle } from "./utilities/authentication/SignInWithGoogle.js";

// Listener triggers every time there is a change in the users sign-in state
auth.onAuthStateChanged(function (user) {

    // if the user is signed in 
    if (user) {
        console.log("User is logged in:", user.displayName);

        // Redirect the user to todo.html page 
        window.location.href = "todo.html";
    
    // if the user is signed out
    } else {
        console.log("User is not logged in");
    }
});

// Function calls signInUserWithGoogle and error checks to see if user has successfully signed in  
async function handleGoogleSignUp(){

    //calls function signInUserWithGoogle and receives a response 
    const response = await signInUserWithGoogle();

    // if an error occurs duing the sign-in process
    if (response === "error") {
        console.log("Error, user not signed in with Google");
    // if the user has successfully signed in
    } else {
        console.log("success, user has signed in with Google");
    }
    
};

// obtaining the button located in 'index.html' through the id 'button'
const signInBtn = document.getElementById("button");

// Listener that will trigger when the signin button is clicked 
// Once Button is clicked function handleGoogleSignUp is called
signInBtn.addEventListener("click", handleGoogleSignUp);