对react中间件的理解

import { createStore, applyMiddleware } from 'redux'
import thunk from 'redux-thunk'
import createLogger rom 'redux-logger'
const logger = createLogger()

const store = createStore(reducer, applyMiddleware(thunk, logger)) // 按顺序执行  从右到左

// 自己修改dispatch,增加logger
let next = store.dispatch
store.dispatch = function dispatchAndLog(action) {
	console.log('dispatching', action)
	next(action)
	console.log('next state', store.getState())
}

const getHomeMultidataAction = () => {
  return (dispatch) => {
    axios.get("http://xxx.xx.xx.xx/test").then(res => {
      const data = res.data.data;
      dispatch(changeBannersAction(data.banner.list));
      dispatch(changeRecommendsAction(data.recommend.list));
    })
  }
}

dispatch(addTodo(text))
dispatch(addTodoAsync(text))

export default function applyMiddleware(...middlewares) {
  return (createStore) => (reducer, preloadedState, enhancer) => {
    var store = createStore(reducer, preloadedState, enhancer);
    var dispatch = store.dispatch;
    var chain = [];
 
    var middlewareAPI = {
      getState: store.getState,
      dispatch: (action) => dispatch(action)
    };
    chain = middlewares.map(middleware => middleware(middlewareAPI));
    dispatch = compose(...chain)(store.dispatch);
 
    return {...store, dispatch}
  }
}

function patchThunk(store) {
   letnext = store.dispatch;

   function dispatchAndThunk(action) {
       if (typeof action === "function") {
           action(store.dispatch, store.getState);
       } else {
           next(action);
       }
   }

   store.dispatch = dispatchAndThunk;
}

let next = store.dispatch;
 
function dispatchAndLog(action) {
  console.log("dispatching:", addAction(10));
  next(addAction(5));
  console.log("新的state:", store.getState());
}
 
store.dispatch = dispatchAndLog;