Update user name within participants of chats

Question

I have the function which updates user data (currently only name). I would like to optimize its logic and particularly logic of updating participant name in chats. Currently I get entire chats collection where I find objects where the participants array contains the current user name (who wants to update their profile) and change its previous name with a new desired name. After that I update the entire chats collection with new data (i.e updatedChats). I need to make it work faster if possible and improve code quality.

Chats collection:

Function code:

 async updateUser(data: IUser) {
    const user = auth.currentUser;
    if (!user) return;
    
    // Updating user name in chats -> chat object -> participants  
    const q = query(collection(db, "chats"));
    const querySnapshot = await getDocs(q);
    const chats = querySnapshot.docs.map((doc) => doc.data() as IChat);

    const updatedChats = chats.map((chat) => {
      if (user.displayName && chat.participants.includes(user.displayName)) {
        if (user.displayName === chat.participants[0]) {
          return {
            ...chat,
            participants: [data.name, chat.participants[1]],
          };
        } else {
          return {
            ...chat,
            participants: [chat.participants[0], data.name],
          };
        }
      }
      return chat;
    });

    await Promise.all(
      updatedChats.map(async (chat) => {
        const chatDocRef = doc(db, "chats", chat.chatId);
        await updateDoc(chatDocRef, { participants: chat.participants });
      })
    );
    
    // other logic
    const userDocRef = doc(db, "users", user.uid);
    await updateDoc(userDocRef, {
      name: data.name,
      bio: data.bio,
    });

    if (auth.currentUser) {
      await updateProfile(auth.currentUser, {
        displayName: data.name,
      });
    }
  }

Answer 1

Data to load can likely be reduced

Instead of loading the entire collection of chats one could load only chats with the participants containing the username - likely using the array-contains operator with the where() method.

Condition to ensure name is set can likely be moved

Also, the second line of the updateUser() method is:

if (!user) return;

while the condition inside the first callback to the map() method is this:

if (user.displayName && chat.participants.includes(user.displayName)) {

The second line of the method could be updated to also ensure the displayName is set and not empty - perhaps checking with a logical AND operator:

if (!(user && user.displayName)) return;

Or using the optional chaining operator ?.:

if (!user?.displayName) return;

Data to update can be simplified

The callback to the map() method returns an updated chat if the displayName is found:

    if (user.displayName === chat.participants[0]) {
      return {
        ...chat,
        participants: [data.name, chat.participants[1]],
      };
    } else {
      return {
        ...chat,
        participants: [chat.participants[0], data.name],
      };
    }

The only line in that block that is different is the participants. One could declare that as a variable which is assigned with the help of a ternary operator. This allows for a single return statement.

    const participants = (user.displayName === chat.participants[0])
      ? participants: [data.name, chat.participants[1]]
      : [chat.participants[0], data.name];
    return {
      ...chat,
      participants
    };