useStateWithPromise.js

import React, { useState, useEffect } from 'react';


const useStateWithPromise = defaultVal => {
  let [state, setState] = useState({
    value: defaultVal,
    resolve: () => {}
  });

  useEffect(
    () => {
      state.resolve(state.value);
    },
    [state]
  );

  return [
    state.value,
    updater => {
      return new Promise(resolve => {
        setState(prevState => {
          let nextVal = updater;
          if (typeof updater === "function") {
            nextVal = updater(prevState.value);
          }
          return {
            value: nextVal,
            resolve
          };
        });
      });
    }
  ];
};

export default useStateWithPromise;