get array from firestore code example

Example 1: get data in from a collection firestore

db.collection("users").get().then((querySnapshot) => {
    querySnapshot.forEach((doc) => {
        console.log(`${doc.id} => ${doc.data()}`);
    });

Example 2: firestore update array

let washingtonRef = db.collection('cities').doc('DC');

// Atomically add a new region to the "regions" array field.
let arrUnion = washingtonRef.update({
  regions: admin.firestore.FieldValue.arrayUnion('greater_virginia')
});
// Atomically remove a region from the "regions" array field.
let arrRm = washingtonRef.update({
  regions: admin.firestore.FieldValue.arrayRemove('east_coast')
});