react-use/src/useGetSetState.ts

import { useCallback, useRef } from 'react';
import useUpdate from './useUpdate';

const useGetSetState = <T extends object>(
  initialState: T = {} as T
): [() => T, (patch: Partial<T>) => void] => {
  if (process.env.NODE_ENV !== 'production') {
    if (typeof initialState !== 'object') {
      console.error('useGetSetState initial state must be an object.');
    }
  }

  const update = useUpdate();
  const state = useRef<T>({ ...(initialState as object) } as T);
  const get = useCallback(() => state.current, []);
  const set = useCallback((patch: Partial<T>) => {
    if (!patch) {
      return;
    }
    if (process.env.NODE_ENV !== 'production') {
      if (typeof patch !== 'object') {
        console.error('useGetSetState setter patch must be an object.');
      }
    }
    Object.assign(state.current, patch);
    update();
  }, []);

  return [get, set];
};

export default useGetSetState;