Firebase Auth & Realtime Database Apps · Lesson

Email/Password Authentication Implementation

Implement user registration and login functionality using email and password credentials with Firebase Authentication.

Email/Password Authentication Implementation is a free Firebase Auth & Realtime Database Apps lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Firebase Auth & Realtime Database Apps learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Email/Password Auth Intro

Welcome to implementing user authentication with Firebase! In this lesson, we'll focus on the most common method: Email and Password.

It's straightforward and widely understood by users.
Firebase handles the secure storage of user credentials.
You'll learn to register new users and sign in existing ones.

Enable Email/Password Provider

Before writing code, you need to enable Email/Password authentication in your Firebase project.

Go to the Firebase console:

Navigate to Authentication.
Click on the Sign-in method tab.
Enable the Email/Password provider.

This tells Firebase to accept these credentials.

Registering New Users

To let new users create an account, you'll use a Firebase Authentication method. This method takes an email and a password, then securely creates a new user record in your Firebase project.

It's crucial to gather the user's email and a strong password from your app's UI.

User Registration Code

Here's how you register a new user using the Firebase SDK. We'll use JavaScript syntax, common for web and mobile apps.

createUserWithEmailAndPassword() is the key function.

import { getAuth, createUserWithEmailAndPassword } from "firebase/auth";

const auth = getAuth();

function registerUser(email, password) {
  createUserWithEmailAndPassword(auth, email, password)
    .then((userCredential) => {
      // Signed up successfully
      const user = userCredential.user;
      console.log("User registered:", user.email);
    })
    .catch((error) => {
      const errorCode = error.code;
      const errorMessage = error.message;
      console.error("Registration error:", errorCode, errorMessage);
    });
}

Signing In Existing Users

Once a user has registered, they can sign in using the same email and password. This process verifies their credentials against the stored records in Firebase.

If the credentials match, Firebase provides a user object, indicating a successful login.

User Login Code

To sign in an existing user, you use signInWithEmailAndPassword(). It works similarly to registration, taking an email and password.

This function also returns a Promise, allowing you to handle success or failure.

import { getAuth, signInWithEmailAndPassword } from "firebase/auth";

const auth = getAuth();

function loginUser(email, password) {
  signInWithEmailAndPassword(auth, email, password)
    .then((userCredential) => {
      // Signed in successfully
      const user = userCredential.user;
      console.log("User logged in:", user.email);
    })
    .catch((error) => {
      const errorCode = error.code;
      const errorMessage = error.message;
      console.error("Login error:", errorCode, errorMessage);
    });
}

Accessing Current User Data

After a user successfully registers or logs in, you can access their information via the currentUser object. This object holds details like their unique ID (UID) and email.

It's vital for personalizing app content.

import { getAuth } from "firebase/auth";

const auth = getAuth();

function displayUserInfo() {
  const user = auth.currentUser;

  if (user) {
    // User is signed in
    console.log("User UID:", user.uid);
    console.log("User Email:", user.email);
    // You can also get user.displayName, user.photoURL, etc.
  } else {
    // No user is signed in
    console.log("No user currently logged in.");
  }
}

Logging Users Out

Providing a way for users to sign out is essential for security and user experience. Firebase Auth makes this simple with the signOut() method.

Calling signOut() clears the user's session.

import { getAuth, signOut } from "firebase/auth";

const auth = getAuth();

function logoutUser() {
  signOut(auth).then(() => {
    // Sign-out successful.
    console.log("User signed out successfully!");
  }).catch((error) => {
    // An error happened.
    console.error("Sign out error:", error);
  });
}

Basic Error Handling

When dealing with authentication, errors are common (e.g., wrong password, email already in use). Firebase provides specific error codes and messages.

Always include .catch() blocks to gracefully handle these issues and provide feedback to your users.

import { getAuth, signInWithEmailAndPassword } from "firebase/auth";

const auth = getAuth();

// Example with error handling
signInWithEmailAndPassword(auth, "wrong@example.com", "badpassword")
  .then((userCredential) => {
    console.log("Login successful!");
  })
  .catch((error) => {
    const errorCode = error.code; // e.g., 'auth/user-not-found'
    const errorMessage = error.message; // e.g., 'There is no user record...'
    console.error("Auth failed:", errorCode, errorMessage);
    // Display user-friendly message based on errorCode
  });

Check Your Knowledge

Which Firebase Authentication method is used to create a new user account with an email and password?

Recap: Email/Password Auth

Great job! You've learned the fundamentals of Email/Password authentication with Firebase.

You enable the provider in the Firebase console.
createUserWithEmailAndPassword() registers new users.
signInWithEmailAndPassword() logs in existing users.
currentUser gives you access to user data.
signOut() logs users out.
Always implement error handling for a robust app.

Next, we'll explore managing user sessions and states!

Frequently asked questions

Is the “Email/Password Authentication Implementation” lesson free?

Yes — the full text of “Email/Password Authentication Implementation” is free to read here on the web, and the Firebase Auth & Realtime Database Apps course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Firebase Auth & Realtime Database Apps course, upgrade to CoddyKit PRO.

What will I learn in “Email/Password Authentication Implementation”?

Implement user registration and login functionality using email and password credentials with Firebase Authentication. You practise Firebase Auth & Realtime Database Apps with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Firebase Auth & Realtime Database Apps?

No prior experience is required. Firebase Auth & Realtime Database Apps on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Email/Password Authentication Implementation” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Firebase Auth & Realtime Database Apps lesson?

Yes. Every Firebase Auth & Realtime Database Apps lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

Email/Password Authentication Implementation
Managing User Sessions & States
Handling Authentication Errors
Password Reset & Email Verification

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