Firebase Firestore Time Stamp
const initFirebase = firebase.initializeApp(firebaseConfig);
const db = initFirebase.firestore();
// időbélyeg hozzáadva
db.serverTimestamp = firebase.firestore.FieldValue.serverTimestamp();
export default db;
The secrets of Firestore’s FieldValue.serverTimestamp() — REVEALED!
https://medium.com/firebase-developers/the-secrets-of-firestore-fieldvalue-servertimestamp-revealed-29dd7a38a82b
Firebase Firestore Time Stamp (how to implement)
https://stackoverflow.com/questions/52854323/firebase-firestore-time-stamp-how-to-implement