Offline persistence in Firebase - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is offline persistence in Firebase?

Offline persistence allows your app to save data locally on the device so it can work without an internet connection and sync changes when back online.

beginner

How do you enable offline persistence in Firebase Firestore for a web app?

You enable it by calling firebase.firestore().enablePersistence() before using Firestore.

beginner

What happens to data changes made while offline in Firebase?

Changes are saved locally and automatically synced to the server when the device reconnects to the internet.

intermediate

Name one limitation of Firebase offline persistence.

Offline persistence has limited storage size and may not support complex queries while offline.

beginner

Why is offline persistence important for mobile apps?

It improves user experience by allowing the app to work smoothly without internet and prevents data loss during connection drops.

How do you enable offline persistence in Firebase Firestore for a web app?

A Set offline: true in config

B Call firebase.firestore().enablePersistence()

C Use firebase.database().goOffline()

D No action needed; it's automatic

You must explicitly call enablePersistence() to turn on offline support in Firestore web apps.

What happens to data written while offline in Firebase Firestore?

A It is saved locally and synced later

B It is sent to the server immediately

C It is lost until connection returns

D It causes an error

Firestore saves offline writes locally and syncs them automatically when online.

Which Firebase product supports offline persistence by default on mobile?

A Firebase Hosting

B Firebase Authentication

C Firebase Firestore

D Firebase Cloud Functions

Firestore supports offline persistence by default on Android and iOS.

What is a common limitation of offline persistence in Firebase?

A No local data storage

B Requires manual sync

C No syncing when online

D Limited local storage size

Offline persistence has limited storage capacity on the device.

Why is offline persistence useful for users?

A It allows app use without internet

B It speeds up internet connection

C It disables data syncing

D It deletes old data

Offline persistence lets users keep using the app even without internet.

Explain how Firebase offline persistence works and why it is useful.

Think about how apps keep working without internet and then update later.

Describe how to enable offline persistence in Firebase Firestore and mention one limitation.

Focus on setup steps and what might not work well offline.