useEnhancedReducer.js

// Fork of https://github.com/shiningjason/react-enhanced-reducer-hook/blob/master/index.js

const useHandler = fn => {
  const ref = useRef({
    fn,
    handler: (...args) => ref.current.fn(...args)
  });
  ref.current.fn = fn;
  return ref.current.handler;
};

const compose = (...fns) => {
  if (fns.length === 0) return arg => arg;
  if (fns.length === 1) return fns[0];
  return fns.reduce((a, b) => (...args) => a(b(...args)));
};

const useEnhancedReducer = (reducer, initialState, middlewares = []) => {
  const [error, setError] = useState();

  const hook = useState(initialState);

  let state = hook[0];

  const setState = hook[1];

  const dispatch = useHandler(action => {
    state = reducer(state, action);
    setState(state);
    return action;
  });

  const getState = useHandler(() => state);

  const storeDispatch = useHandler((...args) => enhancedDispatch(...args));

  const enhancedDispatch = useMemo(() => {
    const chain = middlewares.map(middleware =>
      middleware({ getState, dispatch: storeDispatch, onError: setError })
    );
    return compose(...chain)(dispatch);
  }, []);

  if (error) throw error;

  return [state, enhancedDispatch];
};