Firebase App

Core

import { initializeApp } from 'firebase/app';
const firebaseApp = initializeApp({ /* config */ });

import firebase from 'firebase/app';
const firebaseApp = firebase.initializeApp({ /* config */ });

import { getApp } from 'firebase/app';
const firebaseApp = getApp();

import firebase from 'firebase/app';
const firebaseApp = firebase.apps[0];

import { initializeApp } from 'firebase/app';
const firebaseApp = initializeApp({ /* config */ }, 'named-app');

import firebase from 'firebase/app';
const firebaseApp = firebase.initializeApp({ /* config */ }, 'named-app');

import { getApps } from 'firebase/app';
const namedApp = getApps.find(app => app.name === 'named-app');

import firebase from 'firebase/app';
const namedApp = firebase.apps.find(app => app.name === 'named-app');