Firebase Interview Questions

Firebase is a mobile and web application development platform developed by Firebase, Inc. in 2011, then acquired by Google in 2014.

1. Firebase is a platform which can power your app's backend, including
   • Realtime Database
   • Authentication
   • Hosting
2. Firebase enables you to build cross-platform native mobile and web apps with our Android, iOS, and JavaScript SDKs.
3. You can also connect Firebase to your existing backend using our server-side libraries or our REST API.

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Founders are James Tamplin, Andrew Lee, It was founded in september 2011

1. It is very simple and user friendly.
2. No need for complicated configuration.
3. Firebase offers simple control dashboard.
4. Offers number of useful services.
5. The data is real-time, which means that every change will automatically update connected clients.

FCM: FCM stands for Firebase Cloud Messaging.

GCM: GCM stands for Google Cloud Messaging .

1. Hosting
   − Firebase Hosting provides fast and secure hosting for your web apps and your static and dynamic content.
2. Authentication
   1. Firebase Authentication provides backend services, easy-to-use SDKs, and ready-made UI libraries to authenticate users to your app.
   2. It supports authentication using passwords, phone numbers, popular federated identity providers like Google, Facebook and Twitter, and more.
3. Real-time Database
   1. The Firebase Realtime Database is a cloud-hosted NoSQL database that lets you store and sync data between your users in realtime.
   2. Firebase automatically updates connected clients and store and sync data in real-time across all connected clients and also representing JSON objects or data

   Note: Try Cloud Firestore, the latest realtime, scalable NoSQL database from Firebase and Google Cloud Platform.

4. Push notifications(FCM/GCM)
   − Firebase Cloud Messaging(FCM) is the new version of GCM. It inherits the reliable and scalable GCM infrastructure, plus new features! If you are integrating messaging in a new app, start with FCM.
5. Firebase Analytics
   − Google Analytics for Firebase is a free app measurement solution that provides insight on app usage and user engagement. provides free, unlimited reporting on up to 500 distinct events.
6. Firebase Storage
   − Firebase Storage lets you upload and read raw files to and from the Cloud Storage.
7. Firebase Test Lab for Android
   − Firebase Test Lab is a cloud-based app-testing infrastructure. you can test your Android or iOS app across a wide variety of devices and device configurations, and see the results—including logs, videos, and screenshots—in the Firebase console.

1. Firebase offers two cloud-based, client-accessible database that support realtime data syncing
2. Cloud Firestore offers additional functionality, performance, and scalability on an infrastructure designed to support more powerful features in future releases

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There are different types of event available in the Firebase:

1. child_added − This event type will be triggered once for every player and every time a new player is added to our data.
2. child_changed − This event type is triggered when the data has changed.
3. child_removed − This event will be triggered once every time a child is removed.

When a signed-out user uses an app feature that requires authentication with Firebase, sign in the user anonymously by completing the following steps:

firebase.auth().signInAnonymously().catch(function(error) {
  // Handle Errors here.
  var errorCode = error.code;
  var errorMessage = error.message;
  // ...
});

firebase.auth().onAuthStateChanged(function(user) {
  if (user) {
    // User is signed in.
    var isAnonymous = user.isAnonymous;
    var uid = user.uid;
    // ...
  } else {
    // User is signed out.
    // ...
  }
  // ...
});

Ref - for more details visit Firebase Official Documentation

Firebase Hosting gives you a fast, secure, and reliable way to host your app's static assets (like HTML, CSS, JavaScript, and media files) and serve your dynamic content.

npm install -g firebase-tools

firebase login

firebase init

firebase deploy

Ref - for more details visit Firebase Official Documentation

1. Costs: Firebase free plan is limited to 50 Connections and 100 MB of storage.
2. Hosted solution: Firebase is a hosted solution, so You don’t host the data, Firebase does. You don’t have root access to the location where your data is stored etc

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