Email/password login in Firebase - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Email/Password login in Firebase?

Email/Password login is a method where users sign in using their email address and a password they create. Firebase handles the authentication securely.

intermediate

How does Firebase protect user passwords in Email/Password login?

Firebase stores passwords securely by hashing them, so the actual password is never saved. This keeps user data safe even if the database is accessed.

beginner

What is the first step to enable Email/Password login in Firebase?

You must enable the Email/Password sign-in method in the Firebase Console under Authentication settings.

beginner

What happens if a user tries to sign in with an email that is not registered?

Firebase returns an error indicating the user does not exist, prompting the user to register first.

beginner

Why is Email/Password login considered user-friendly?

Because most people are familiar with using an email and password to access services, making it easy to understand and use.

What must you do first to use Email/Password login in Firebase?

A Enable Email/Password sign-in in Firebase Console

B Write custom backend code

C Create a new Firebase project

D Install a third-party plugin

You must enable Email/Password sign-in in the Firebase Console before users can log in this way.

How does Firebase store passwords for Email/Password login?

A In plain text

B Encrypted with a reversible key

C Hashed securely

D Not stored at all

Firebase hashes passwords securely so they cannot be read even if accessed.

What error occurs if a user enters a wrong password?

A Wrong password error

B No error, login succeeds

C Account locked

D User not found

Firebase returns a wrong password error if the password does not match the stored hash.

Which Firebase service handles Email/Password login?

A Cloud Firestore

B Firebase Authentication

C Firebase Hosting

D Firebase Functions

Firebase Authentication manages user sign-in methods including Email/Password.

Can users reset their password if they forget it in Email/Password login?

A Passwords reset automatically every month

B No, they must create a new account

C Only admins can reset passwords

D Yes, via Firebase password reset email

Firebase provides a password reset email feature to help users recover access.

Explain how to set up Email/Password login in Firebase from start to finish.

Think about the steps from enabling the feature to handling user actions.

Describe how Firebase keeps user passwords safe in Email/Password login.

Focus on what happens to the password after user submits it.

Practice

1. What is the main purpose of using email/password login in Firebase?

easy

A. To allow users to create accounts and sign in securely

B. To store user data in a database

C. To send emails to users automatically

D. To host a website on Firebase

Solution

1. Step 1: Understand the feature purpose

   Email/password login lets users create accounts and sign in using their email and a password.

2. Step 2: Identify the correct use case

   This method is mainly for user authentication, not for storing data or sending emails.

3. Final Answer:

   To allow users to create accounts and sign in securely -> Option A

4. Quick Check:

   Email/password login = user sign-in [OK]

Hint: Email/password login is for user sign-in only [OK]

Common Mistakes:

• Confusing login with data storage
• Thinking it sends emails automatically
• Assuming it hosts websites

2. Which Firebase method is used to create a new user with email and password?

easy

A. firebase.auth().createUserWithEmailAndPassword(email, password)

B. firebase.auth().sendPasswordResetEmail(email)

C. firebase.auth().signInWithEmailAndPassword(email, password)

D. firebase.auth().signOut()

Solution

1. Step 1: Identify method for new user creation

   The method to create a new user is createUserWithEmailAndPassword.

2. Step 2: Differentiate from other methods

   signInWithEmailAndPassword is for login, sendPasswordResetEmail is for resetting password, signOut logs out the user.

3. Final Answer:

   firebase.auth().createUserWithEmailAndPassword(email, password) -> Option A

4. Quick Check:

   Create user method = createUserWithEmailAndPassword [OK]

Hint: Create user uses 'createUserWithEmailAndPassword' [OK]

Common Mistakes:

• Using signInWithEmailAndPassword to create users
• Confusing reset email with user creation
• Calling signOut instead of createUser

3. What will happen if you run this code snippet?

firebase.auth().signInWithEmailAndPassword('[e-mail]', 'wrongpass')
  .catch(error => console.log(error.code));

medium

A. Logs 'auth/user-not-found' error code

B. Logs 'auth/network-request-failed' error code

C. Logs 'auth/invalid-email' error code

D. Logs 'auth/wrong-password' error code

Solution

1. Step 1: Understand signInWithEmailAndPassword behavior

   This method tries to sign in with given email and password.

2. Step 2: Analyze error for wrong password

   If the email exists but password is wrong, Firebase returns 'auth/wrong-password'.

3. Final Answer:

   Logs 'auth/wrong-password' error code -> Option D

4. Quick Check:

   Wrong password error = 'auth/wrong-password' [OK]

Hint: Wrong password triggers 'auth/wrong-password' error [OK]

Common Mistakes:

• Assuming user-not-found error instead
• Confusing invalid email format error
• Thinking network error will occur

4. Identify the error in this Firebase email/password login code:

firebase.auth().signInWithEmailAndPassword(email, password)
  .then(userCredential => {
    console.log('User signed in:', userCredential.user);
  })
  .catch(error => {
    console.log('Error:', error.message);
  });

Assume email and password are not defined.

medium

A. Missing import of firebase module

B. Variables email and password are undefined

C. Incorrect method name used

D. No catch block for errors

Solution

1. Step 1: Check variable definitions

   The code uses email and password variables but they are not defined anywhere.

2. Step 2: Confirm method and error handling

   The method signInWithEmailAndPassword is correct and there is a catch block for errors.

3. Final Answer:

   Variables email and password are undefined -> Option B

4. Quick Check:

   Undefined variables cause runtime error [OK]

Hint: Always define email and password before use [OK]

Common Mistakes:

• Ignoring variable definitions
• Thinking method name is wrong
• Missing error handling block

5. You want to ensure users create strong passwords during Firebase email/password signup. Which approach is best?

hard

A. Use Firebase's built-in password strength validation only

B. Send password to server for manual strength checking after signup

C. Check password strength on client side before calling createUserWithEmailAndPassword

D. Allow any password and rely on Firebase error messages

Solution

1. Step 1: Understand Firebase password validation

   Firebase requires minimum 6 characters but does not enforce strong passwords by default.

2. Step 2: Implement client-side password strength check

   Checking password strength on client side before signup improves security and user experience.

3. Final Answer:

   Check password strength on client side before calling createUserWithEmailAndPassword -> Option C

4. Quick Check:

   Client-side validation = better password strength [OK]

Hint: Validate password strength before signup call [OK]

Common Mistakes:

• Relying only on Firebase's minimal checks
• Ignoring password strength until after signup
• Sending passwords to server for manual checks