My webapp will have chat rooms, i need to implement list of users in that chat rooms.

1. What is the best way to do that? By subcollection or array?

If array: How to update just one field in document? ( How to add user.uid to array )

If subcollection: How to get acces to subcolection in v9 firestore?

Code for creating room:

await addDoc(collection(db, "rooms"), {
            creator_uid: uid,
            name: _name,
            secured: is_secured,
            password: pass,
            room_members: [],
        });