react 中使用redux的createStore 创建公用变量

import { createStore } from 'redux'
import { useState } from 'react';


export const store = createStore(addTodo, 0);



function addTodo(state = 0, { type, num = 1 }) {
    switch (type) {
        case "add":
            return state + num;
        case "update":
            return num;
        default:
            return state;
    }
}




export const useStore = function (store){



  const [stateValue, setStateValue] = useState(store.getState())



  //变更订阅
  store.subscribe(function(){
    setStateValue(store.getState());
  })



  const set = function(val){
    store.dispatch({ type: 'update', num: val });
  }



  return [stateValue, set];
}

import logo from './logo.svg';
import './App.css';


import { store, useStore } from './redux/index'




export const Dom1 = function(){
  const [s] = useStore(store);
  return <div> {s} </div>
}



function App() {



  const [s, ss] = useStore(store);



  const changeStore = function (){
    ss( s + 1 );
  }



  return (
    <div className="App">
      <header className="App-header">
        <img src={logo} className="App-logo" alt="logo" />
        <p>
          Edit <code>src/App.js</code> and save to reload.
        </p>
        <p onClick={ changeStore }>{ s }</p>



        <Dom1></Dom1>



      </header>
    </div>
  );
}



export default App;