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Authenticate Using with JavaScript
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You can let your users authenticate with Firebase using their accounts by integrating authentication into your app. You can integrate authentication either by using the Firebase SDK to carry out the sign-in flow, or by carrying out the OAuth 2.0 flow manually and passing the resulting access token to Firebase.

Before you begin

Add Firebase to your JavaScript project.
In the Firebase console, open the Auth section.
On the Sign in method tab, enable the provider.
Add the Client ID and Client Secret from that provider's developer console to the provider configuration:
1. Register your app as a developer application on and get your app's OAuth 2.0 Client ID and Client Secret.
2. Make sure your Firebase OAuth redirect URI (e.g. my-app-12345.firebaseapp.com/__/auth/handler) is set as your Authorization callback URL in your app's settings page on your app's config.
Click Save.

Handle the sign-in flow with the Firebase SDK

If you are building a web app, the easiest way to authenticate your users with Firebase using their accounts is to handle the sign-in flow with the Firebase JavaScript SDK. (If you want to authenticate a user in Node.js or other non-browser environment, you must handle the sign-in flow manually.)

To handle the sign-in flow with the Firebase JavaScript SDK, follow these steps:

Create an instance of the provider object:

Web

import { AuthProvider } from "firebase/auth";

const provider = new AuthProvider();auth__provider_create.js

Web

var provider = new firebase.auth.AuthProvider();.js

Optional: Specify additional OAuth 2.0 scopes that you want to request from the authentication provider. To add a scope, call addScope. For example:
Web
```
provider.addScope('repo');auth__provider_scopes.js
```
Web
```
provider.addScope('repo');.js
```
See the authentication provider documentation.
Optional: Specify additional custom OAuth provider parameters that you want to send with the OAuth request. To add a custom parameter, call setCustomParameters on the initialized provider with an object containing the key as specified by the OAuth provider documentation and the corresponding value. For example:
Web
```
provider.setCustomParameters({
  'allow_signup': 'false'
});auth__provider_params.js
```
Web
```
provider.setCustomParameters({
  'allow_signup': 'false'
});.js
```
Reserved required OAuth parameters are not allowed and will be ignored. See the authentication provider reference for more details.

Authenticate with Firebase using the provider object. You can prompt your users to sign in with their accounts either by opening a pop-up window or by redirecting to the sign-in page. The redirect method is preferred on mobile devices.

To sign in with a pop-up window, call signInWithPopup:

Web

import { getAuth, signInWithPopup, AuthProvider } from "firebase/auth";

const auth = getAuth();
signInWithPopup(auth, provider)
  .then((result) => {
    // This gives you a  Access Token. You can use it to access the  API.
    const credential = AuthProvider.credentialFromResult(result);
    const token = credential.accessToken;

    // The signed-in user info.
    const user = result.user;
    // IdP data available using getAdditionalUserInfo(result)
    // ...
  }).catch((error) => {
    // Handle Errors here.
    const errorCode = error.code;
    const errorMessage = error.message;
    // The email of the user's account used.
    const email = error.customData.email;
    // The AuthCredential type that was used.
    const credential = AuthProvider.credentialFromError(error);
    // ...
  });auth__signin_popup.js

Web

firebase
  .auth()
  .signInWithPopup(provider)
  .then((result) => {
    /** @type {firebase.auth.OAuthCredential} */
    var credential = result.credential;

    // This gives you a  Access Token. You can use it to access the  API.
    var token = credential.accessToken;

    // The signed-in user info.
    var user = result.user;
    // IdP data available in result.additionalUserInfo.profile.
      // ...
  }).catch((error) => {
    // Handle Errors here.
    var errorCode = error.code;
    var errorMessage = error.message;
    // The email of the user's account used.
    var email = error.email;
    // The firebase.auth.AuthCredential type that was used.
    var credential = error.credential;
    // ...
  });.js

Also notice that you can retrieve the provider's OAuth token which can be used to fetch additional data using the APIs.

This is also where you can catch and handle errors. For a list of error codes have a look at the Auth Reference Docs.

To sign in by redirecting to the sign-in page, call signInWithRedirect: Follow the best practices when using `signInWithRedirect`.

Web

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

const auth = getAuth();
signInWithRedirect(auth, provider);auth_signin_redirect.js

Web

firebase.auth().signInWithRedirect(provider);index.js

Then, you can also retrieve the provider's OAuth token by calling getRedirectResult when your page loads:

Web

import { getAuth, getRedirectResult, AuthProvider } from "firebase/auth";

const auth = getAuth();
getRedirectResult(auth)
  .then((result) => {
    const credential = AuthProvider.credentialFromResult(result);
    if (credential) {
      // This gives you a  Access Token. You can use it to access the  API.
      const token = credential.accessToken;
      // ...
    }

    // The signed-in user info.
    const user = result.user;
    // IdP data available using getAdditionalUserInfo(result)
    // ...
  }).catch((error) => {
    // Handle Errors here.
    const errorCode = error.code;
    const errorMessage = error.message;
    // The email of the user's account used.
    const email = error.customData.email;
    // The AuthCredential type that was used.
    const credential = AuthProvider.credentialFromError(error);
    // ...
  });auth__signin_redirect_result.js

Web

firebase.auth()
  .getRedirectResult()
  .then((result) => {
    if (result.credential) {
      /** @type {firebase.auth.OAuthCredential} */
      var credential = result.credential;

      // This gives you a  Access Token. You can use it to access the  API.
      var token = credential.accessToken;
      // ...
    }

    // The signed-in user info.
    var user = result.user;
    // IdP data available in result.additionalUserInfo.profile.
      // ...
  }).catch((error) => {
    // Handle Errors here.
    var errorCode = error.code;
    var errorMessage = error.message;
    // The email of the user's account used.
    var email = error.email;
    // The firebase.auth.AuthCredential type that was used.
    var credential = error.credential;
    // ...
  });.js

This is also where you can catch and handle errors. For a list of error codes have a look at the Auth Reference Docs.

Handling account-exists-with-different-credential Errors

If you enabled the One account per email address setting in the Firebase console, when a user tries to sign in a to a provider (such as ) with an email that already exists for another Firebase user's provider (such as Google), the error auth/account-exists-with-different-credential is thrown along with an AuthCredential object ( access token). To complete the sign in to the intended provider, the user has to sign first to the existing provider (Google) and then link to the former AuthCredential ( access token).

If you use signInWithPopup, you can handle auth/account-exists-with-different-credential errors with code like the following example:

import {
  getAuth,
  linkWithCredential,
  signInWithPopup,
  AuthProvider,
} from "firebase/auth";

try {
  // Step 1: User tries to sign in using .
  let result = await signInWithPopup(getAuth(), new AuthProvider());
} catch (error) {
  // Step 2: User's email already exists.
  if (error.code === "auth/account-exists-with-different-credential") {
    // The pending  credential.
    let pendingCred = error.credential;

    // Step 3: Save the pending credential in temporary storage,

    // Step 4: Let the user know that they already have an account
    // but with a different provider, and let them choose another
    // sign-in method.
  }
}

// ...

try {
  // Step 5: Sign the user in using their chosen method.
  let result = await signInWithPopup(getAuth(), userSelectedProvider);

  // Step 6: Link to the  credential.
  // TODO: implement `retrievePendingCred` for your app.
  let pendingCred = retrievePendingCred();

  if (pendingCred !== null) {
    // As you have access to the pending credential, you can directly call the
    // link method.
    let user = await linkWithCredential(result.user, pendingCred);
  }

  // Step 7: Continue to app.
} catch (error) {
  // ...
}

Redirect mode

This error is handled in a similar way in the redirect mode, with the difference that the pending credential has to be cached between page redirects (for example, using session storage).

Handle the sign-in flow manually

You can also authenticate with Firebase using a account by handling the sign-in flow by calling the OAuth 2.0 endpoints:

Integrate authentication into your app by following the developer's documentation. At the end of the sign-in flow, you will receive an OAuth 2.0 access token.
If you need to sign in on a Node.js application, send the OAuth access token to the Node.js application.

After a user successfully signs in with , exchange the OAuth 2.0 access token for a Firebase credential:

Web

import { AuthProvider } from "firebase/auth";

const credential = AuthProvider.credential(token);auth__provider_credential.js

Web

var credential = firebase.auth.AuthProvider.credential(token);.js

Authenticate with Firebase using the Firebase credential:

Web

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

// Sign in with the credential from the user.
const auth = getAuth();
signInWithCredential(auth, credential)
  .then((result) => {
    // Signed in 
    // ...
  })
  .catch((error) => {
    // Handle Errors here.
    const errorCode = error.code;
    const errorMessage = error.message;
    // The email of the user's account used.
    const email = error.customData.email;
    // ...
  });auth_signin_credential.js

Web

// Sign in with the credential from the user.
firebase.auth()
  .signInWithCredential(credential)
  .then((result) => {
    // Signed in 
    // ...
  })
  .catch((error) => {
    // Handle Errors here.
    const errorCode = error.code;
    const errorMessage = error.message;
    // The email of the user's account used.
    const email = error.email;
    // ...
  });index.js

Authenticate with Firebase in a Chrome extension

If you are building a Chrome extension app, see the Offscreen Documents guide.

On project creation, Firebase will provision a unique subdomain for your project: https://my-app-12345.firebaseapp.com.

This will also be used as the redirect mechanism for OAuth sign in. That domain would need to be allowed for all supported OAuth providers. However, this means that users may see that domain while signing in to before redirecting back to the application: Continue to: https://my-app-12345.firebaseapp.com.

To avoid displaying your subdomain, you can set up a custom domain with Firebase Hosting:

Follow steps 1 through 3 in Set up your domain for Hosting. When you verify your domain ownership, Hosting provisions an SSL certificate for your custom domain.
Add your custom domain to the list of authorized domains in the Firebase console: auth.custom.domain.com.
In the developer console or OAuth setup page, whitelist the URL of the redirect page, which will be accessible on your custom domain: https://auth.custom.domain.com/__/auth/handler.

When you initialize the JavaScript library, specify your custom domain with the authDomain field:

var config = {
  apiKey: '...',
  // Changed from 'PROJECT_ID.firebaseapp.com'.
  authDomain: 'auth.custom.domain.com',
  databaseURL: 'https://PROJECT_ID.firebaseio.com',
  projectId: 'PROJECT_ID',
  storageBucket: 'PROJECT_ID.firebasestorage.app',
  messagingSenderId: 'SENDER_ID'
};
firebase.initializeApp(config);

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:

Web

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

const auth = getAuth();
signOut(auth).then(() => {
  // Sign-out successful.
}).catch((error) => {
  // An error happened.
});auth_sign_out.js

Web

firebase.auth().signOut().then(() => {
  // Sign-out successful.
}).catch((error) => {
  // An error happened.
});index.js

Authenticate Using with JavaScriptStay organized with collections Save and categorize content based on your preferences.