Firebase Authentication provides backend services to authenticate users in Single Page Applications (SPA). To implement, initialize Firebase SDK in your SPA. Use the ‘firebase.auth()’ function for authentication.
For sign-up, use ‘createUserWithEmailAndPassword(email, password)’ method. It creates a new user account using an email and password and returns user data.
To log-in existing users, use ‘signInWithEmailAndPassword(email, password)’. If successful, it returns user information.
To maintain user sessions, use ‘onAuthStateChanged(user)’. This observer triggers every time user’s sign-in state changes. It helps in maintaining user sessions across refreshes or re-openings of the app.
For sign-out, use ‘signOut()’ method. It invalidates the session on the client side.
Remember to handle errors during these processes by catching them and providing appropriate feedback to users.