function exampleMiddleware(storeAPI) {
  return function wrapDispatch(next) {
    return function handleAction(action) {
      // 在這里做你想做的事情，做完后，通過返回next(action)向下一個(gè)middleware傳遞action
      return next(action)
    }
  }
}

const exampleMiddleware = store => next => action => {
  return next(action)
}

import { createStore, applyMiddleware } from 'redux'
import rootReducer from './reducer'
import { print1, print2, print3 } from './exampleAddons/middleware'
const middlewareEnhancer = applyMiddleware(print1, print2, print3)
const store = createStore(rootReducer, middlewareEnhancer)
export default store

// 省略了中間代碼并去除typescript類型，并將Compose和applyMiddleware函數(shù)放在一起便于展示
function compose(...funcs) {
	// 沒有傳入middleware，直接返回
	if (funcs.length === 0) {
	  return (arg) => arg
	}
	// 傳入一個(gè)middleware，無需構(gòu)造，直接返回
	if (funcs.length === 1) {
	  return funcs[0]
	}
	// 進(jìn)行函數(shù)柯里化返回一個(gè)形如：fn1(fn2(fn3(store.dispatch))) 的新dispatch函數(shù)
	return funcs.reduce(
	  (a, b) =>
	    (...args: any) =>
	      a(b(...args))
	)
}
function applyMiddleware(...middlewares){
	return (createStore) => (reducer, preloadedState) => {
		// createStore中檢測到由applyMiddleware函數(shù)生成的enhancer時(shí)，將createStore、reducer、initialState傳入，在函數(shù)中創(chuàng)建一個(gè)臨時(shí)的store
		const store = createStore(reducer, preloadedState)
		// 創(chuàng)建一個(gè)臨時(shí)的dispatch函數(shù)，此函數(shù)拋出異常，用于防止處理傳入的middlewares時(shí)提前調(diào)用dispatch
		let dispatch = () => {
			throw new Error(
			  'Dispatching while constructing your middleware is not allowed. ' +
			    'Other middleware would not be applied to this dispatch.'
			)
		}
		// 給middleware分發(fā)store
		const middlewareAPI = {
		  getState: store.getState,
		  dispatch: (action, ...args) => dispatch(action, ...args)
		}
		// 讓每個(gè)middleware帶著middlewareAPI這個(gè)參數(shù)執(zhí)行一遍，然后獲得帶著相同的store的middlewares
		const chain = middlewares.map(middleware => middleware(middlewareAPI))
		// 將所有chain中的函數(shù)利用Compose函數(shù)組裝成一個(gè)新的dispatch函數(shù)
		// 如：dispatch=fn1(fn2(fn3(store.dispatch)))
		dispatch = compose(...chain)(store.dispatch)
		// 將生成的dispatch函數(shù)整合到剛才生成的store中并返回
		return {
		  ...store,
		  dispatch
		}
	}
}