Lazy Load Import Firebase (dynamic import)

firebase.js

Promise.all([
  import('firebase/app'),
  import('firebase/database'),
  import('firebase/auth'),
])
  .then(x => x[0].default)
  .then(firebase => {
    const config = {
      apiKey: '',
      authDomain: '',
      databaseURL: '',
      projectId: '',
      storageBucket: '',
      messagingSenderId: '',
    }

    firebase.initializeApp(config)

    if (global.firebase) {
      return global.firebase
    } else if (!firebase) {
      return Promise.reject(new Error('loading error'))
    } else {
      global.firebase = firebase

      const googleAuthProvider = new firebase.auth.GoogleAuthProvider()
      googleAuthProvider.addScope('https://www.googleapis.com/auth/userinfo.email')

      global.firebase.googleAuthProvider = googleAuthProvider
      
      return global.firebase ? global.firebase : firebase
    }
  })
  .catch(err => {
    throw new Error(err)
  })

This hook looks fine to me. You can optimize it by using a reducer instead of 3 different state variables because the hook will run at least 4 times (once for each "setState"), but that is besides the point here. Where are you running this hook from? Is it running inside a function component?

One other thing I'm thinking of now is that if the component you are calling this from looks something like this:

const YourComponent = () => {
  const { firebase, isLoading, error } = useFirebase()

  if (error) {
    return <ErrorComponent />
  }

  if (isLoading) {
    return <Loader />
  }

  return (
    <MainComponent firebase={firebase} />
  )
}

The first render, isLoading will be false and error will be null, so it will skip the checks, but firebase will still be undefined. Maybe that is happening now? You can default your isLoading state to true instead.

Thanks, eventually I've made it work.
But even it's working now in lazy mode I've noticed that in the browser the full firebase library is still loaded in the initial chunk. Shouldn't it be the opposite? to load it on demand?
(I'm using 'next/dynamic' that I think it's the equivalent to React.Lazy)

I'm not sure. I think that depends on the Webpack config Next.js is using under the hood, but generally, if you use the import() syntax a separate chunk will be created. Only thing I can think of right now is to make sure you aren't importing or including Firebase somewhere else already.

ok, I guess I need to dig into it a bit. Thanks!

I added caching and here is what I ended up with:

async function getFirebaseClient(){
  const { default: firebase } = await import("firebase/app")

  await Promise.all([
    import("firebase/auth"),
    //   import('firebase/storage'),
    import("firebase/firestore"),
  ])

  const config = {
.....
  }

  firebase.initializeApp(config)
  firebase.firestore()
  return firebase
}

let cached = null

export function fb() {

    if (cached || process.server) return cached

    cached = getFirebaseClient()
    return cached
}

This is how it can be used

import { fb } from "~/js/firebase-loader"


// get lazy loading started
fb()


async function sample(){
   const firebase = await fb()
    firebase.auth()....
}

One benefit is that fb can be imported from multiple places, but still the result will be shared.

Very nice @husayt

I have error when trying these steps with typescripts

Hi @rodbs

I personally do this to import the firebase client and admin SDK's as I need them in Next.js

The client SDK

const firebaseConfig = {
  apiKey: process.env.NEXT_PUBLIC_FIREBASE_API_KEY,
  authDomain: process.env.NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN,
  databaseURL: process.env.NEXT_PUBLIC_FIREBASE_DATABASE_URL,
  projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
  storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET,
  messagingSenderId: process.env.NEXT_PUBLIC_FIREBASE_MESSAGING_SENDER_ID,
  appId: process.env.NEXT_PUBLIC_FIREBASE_APP_ID,
  measurementId: process.env.NEXT_PUBLIC_FIREBASE_MEASUREMENT_ID,
}

export const getFirebaseClient = async () => {
  const firebase = await import('firebase/app')

  await Promise.all([
    import('firebase/auth'),
    import('firebase/storage'),
    import('firebase/firestore'),
  ])

  if (!firebase.apps.length) {
    firebase.initializeApp(firebaseConfig)
  }

  return firebase
}

The admin SDK

import * as admin from 'firebase-admin'

export const getAdminClient = () => {
  if (!admin.apps.length) {
    const privateKeyBuffer = Buffer.from(
      process.env.FIREBASE_PRIVATE_KEY_BASE64 || '',
      'base64'
    )
    const firebasePrivateKey = privateKeyBuffer.toString('utf8')

    admin.initializeApp({
      credential: admin.credential.cert({
        projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
        clientEmail: process.env.FIREBASE_CLIENT_EMAIL,
        privateKey: firebasePrivateKey,
      }),
      databaseURL: process.env.NEXT_PUBLIC_FIREBASE_DATABASE_URL,
      storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET,
    })
  }

  return admin
}

but adding const firebase = (await import('firebase/app')).default into it seems to work

Thanks @mimiqkz

any update for v9 ?

@qxygene Yeah, I stopped on this thread during a 6-hour journey to find how to lazy load the treeshakeable imports for Firebase v9. Everyone seemed nice, so I came back with a solution. Shout out to https://twitter.com/gabe_ragland/status/1417516444686839809 for the og solution. Hope this helps anyone struggling on v9 like I was.

Firebase Setup

/***** firebase/app.js *****/

import fbConfig from "./config";
import { initializeApp, getApp, getApps } from "firebase/app";

const setupFirebase = () => {
  if (getApps.length) return getApp();
  return initializeApp( /* Your Firebase Config */);
};

export const app = setupFirebase();



/***** firebase/auth.js *****/

import { getAuth } from "firebase/auth";
import { app } from "./app.js";

// Export initialized Firestore "auth"
export const auth = getAuth(app);

//Export just what you need
export {
  signInWithEmailAndPassword,
  createUserWithEmailAndPassword,
} from "firebase/auth";



/***** firebase/firestore.js *****/

import { getFirestore } from "firebase/firestore";
import { app } from "./app.js";

// Export initialized Firestore "DB"
export const db = getFirestore(app);

//Export just what you need
export {
  collection,
  query,
  where,
  orderBy,
  onSnapshot,
} from "firebase/firestore";

Usage in Project

// Dynamically import subset of Auth Methods
const getAuth = () => import("../firebase/auth.js")

// Dynamically import subset of Firestore Methods
const getDb = () => import("../firebase/firestore.js")

/**
* Get them both at the same time
* Usage: const { firestore: { db, query, collection, where, orderBy, onSnapshot } } = await getFirebaseAll()
*/
const getFirebaseAll = () => {
  return Promise.all([
    import("../firebase/auth"),
    import("../firebase/firestore"),
  ]).then(([auth, firestore]) => {
    return { auth, firestore };
  });
};

/****** Example ******/

const onSignup = async (email, password) => {
    // Use await to ensure the library is loaded 
    const { auth, createUserWithEmailAndPassword } = await getFirebase()

    // Call the method like normal
    const { user } = await createUserWithEmailAndPassword(auth, email, password)

    // Do whatever else
} 

credit: https://twitter.com/gabe_ragland/status/1417516444686839809

thank you, works nice. But one thing for auth; when i refresh page and update doc, i receive an error => FirebaseError: Missing or insufficient permissions. If i dont refresh page all works fine.

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
 match /users/{document=**} {
      allow read;
      allow write: if request.auth != null;
    }
  }
}

@Jaseibert Thanks this works great.

To add on, I also made my own firebase types/interface files (I am using typescript), then I re-wrote firebase code I needed to use which I couldn't wait for (such as Timestamp) in my own files without the bloat. Lastly I made sure I absolutely never imported from firebase/(any of them) outside of the root firestore files were created from your guide.

The second step of the optimization I explained above took and extra 125kB+ off the bundle. After optimizing just firebase my first load JS shared by all went from 320kB to 125kB! (I use functions, storage, firestore, and auth)

You can use this eslint rule to prevent importing firebase directly:
"no-restricted-imports": ["error", "firebase/app", "firebase/firestore", "firebase/storage", "firebase/auth", "firebase/functions"]