initFirebaseAuth.js

import firebase from "firebase/app";
import 'firebase/auth';
import StyledFirebaseAuth from 'react-firebaseui/StyledFirebaseAuth';

initAuth(){
    var config = {
        apiKey: "<key>",
        authDomain: "unicorn-platform-app.firebaseapp.com",
        databaseURL: "https://unicorn-platform-app.firebaseio.com",
        projectId: "unicorn-platform-app",
        storageBucket: "unicorn-platform-app.appspot.com",
        messagingSenderId: "<senderId>"
    };
    firebase.initializeApp(config);
    firebase.auth().onAuthStateChanged(function(user) {
        // if (user) {
            // User is signed in and currentUser will no longer return null.
        // } else {
            // No user is signed in.
        // }
    });
}