Firebase Channel Creator for VueX: The code makes a VueX store action which modifies the state according to data received from Firebase Firestore

gistfile1.js

channelBookings({ state, commit }, user_id) {
    var book = [];
    db.collection("bookings").onSnapshot(res => {
      const changes = res.docChanges();
      changes.forEach(change => {
        switch (change.type) {
          case "added":
            book.push({
              ...change.doc.data(),
              id: change.doc.id
            });
            commit("BOOKING_CHANNEL", { type: change.type, bookings: book });
            break;

          case "removed":
            book = state.bookings;
            var index = book
              .map(boo => {
                return boo.id;
              })
              .indexOf(change.doc.id);
            commit("BOOKING_CHANNEL", {
              type: change.type,
              booking_index: index
            });
            break;

          case "modified":
            book = state.bookings;
            var index = book
              .map(boo => {
                return boo.id;
              })
              .indexOf(change.doc.id);
            commit("BOOKING_CHANNEL", {
              type: change.type,
              booking_index: index,
              bookings: change.doc.data()
            });
            break;
        }
      });
    });
  },