Working instance of linkStateWithPath

linkStoreWithPath.js

const linkStoreWithPath = (path, actionCreator, selector) => {
  return (db, store) => {
    let previous = selector(store.getState());
    let mustWrite = true;

    const fromDb = (db, dispatch) => {
      const listener = db.ref(path).on("value", snap => {
        if (snap.val()) {
          mustWrite = false;
          dispatch(actionCreator(snap.val()));
          mustWrite = true;
        }
      });
      return () => db.ref(path).of("value", listener);
    };

    const fromStore = (state, db) => {
      const portion = selector(state);
      if (mustWrite && portion !== previous) {
        db.ref(path).set(portion);
      }
      previous = portion;
    };

    return linkStoreWithDb(fromDb, fromStore)(db, store);
  };
}