Sample Firebase config

firestore.js

import firebase from '@firebase/app';
import '@firebase/firestore';

firebase.initializeApp({
  apiKey: 'YOUR_API_KEY',
  // Configure the above client key at https://console.cloud.google.com/apis/credentials
  // Restrict to: *.your-domain.com/* (and localhost for testing)
  // Restrict to: Google Cloud Firestore API, Identity Toolkit API
  authDomain: 'your-app.firebaseapp.com',
  projectId: 'your-app'
});

firebase.firestore().settings({ timestampsInSnapshots: true });

export default firebase.firestore().enablePersistence()
  .then(() => firebase.firestore())
  .catch(error => firebase.firestore());