Authenticate with Firebase using Password-Based Accounts using Javascript

You can use Firebase Authentication to let your users authenticate with Firebase using their email addresses and passwords, and to manage your app's password-based accounts.

Before you begin

Add Firebase to your JavaScript project.
If you haven't yet connected your app to your Firebase project, do so from the Firebase console.
Enable Email/Password sign-in:
1. In the Firebase console, open the Auth section.
2. On the Sign in method tab, enable the Email/password sign-in method and click Save.

Create a password-based account

To create a new user account with a password, complete the following steps in your app's sign-up page:

When a new user signs up using your app's sign-up form, complete any new account validation steps that your app requires, such as verifying that the new account's password was correctly typed and meets your complexity requirements.
Create a new account by passing the new user's email address and password to createUserWithEmailAndPassword:
```
firebase.auth().createUserWithEmailAndPassword(email, password).catch(function(error) {
  // Handle Errors here.
  var errorCode = error.code;
  var errorMessage = error.message;
  // ...
});
```
If the new account was created, the user is signed in automatically. Have a look at the Next steps section below to get the signed in user details.
This is also where you can catch and handle errors. For a list of error codes have a look at the Auth Reference Docs.

Sign in a user with an email address and password

The steps for signing in a user with a password are similar to the steps for creating a new account. In your app's sign-in page, do the following:

When a user signs in to your app, pass the user's email address and password to signInWithEmailAndPassword:
```
firebase.auth().signInWithEmailAndPassword(email, password).catch(function(error) {
  // Handle Errors here.
  var errorCode = error.code;
  var errorMessage = error.message;
  // ...
});
```
Have a look at the Next steps section below to get the signed in user details.
This is also where you can catch and handle errors. For a list of error codes have a look at the Auth Reference Docs.

Next steps

After a user signs in for the first time, a new user account is created and linked to the credentials—that is, the user name and password, phone number, or auth provider information—the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in.

In your apps, the recommended way to know the auth status of your user is to set an observer on the Auth object. You can then get the user's basic profile information from the User object. See Manage Users.
In your Firebase Realtime Database and Cloud Storage Security Rules, you can get the signed-in user's unique user ID from the auth variable, and use it to control what data a user can access.

You can allow users to sign in to your app using multiple authentication providers by linking auth provider credentials to an existing user account.

To sign out a user, call signOut:

firebase.auth().signOut().then(function() {
  // Sign-out successful.
}).catch(function(error) {
  // An error happened.
});