09.使用react-thunk解决异步action问题

使用方式

import { createStore, applyMiddleware } from 'redux'
import thunk from 'redux-thunk'
const store = createStore(weight, applyMiddleware(thunk))

export const eatAsync = () =>{
  return dispatch =>{
    setTimeout(()=>{
      // dispatch(eat('煎饼')) 
      dispatch({type: EAT}) 
    },2000)
  }
}

源码

import { createStore } from 'redux'
const EAT = 'eat'
const HUNGRY = 'hungry'
// reducer
export const weight = (state = 160 , action) => {
  switch (action.type) {
    case EAT:
      return state + 10
    case HUNGRY:
      return state - 10
    default:
      return 160
  }
}
// const store = createStore(weight)
// action
export const eat = (data) => {
  console.log('stark wang 正在吃'+ data)
  return {type: EAT}
}
export const hungry = () => {
  console.log('饿了一天')
  return {type: HUNGRY}
}
export const eatAsync = () =>{
  return dispatch =>{
    setTimeout(()=>{
      dispatch(eat('煎饼')) 
    },2000)
  }
}

import React from 'react'
import logo from './logo.svg'
import './App.css'
import { eat, hungry, eatAsync } from './stark.redux'
import { connect } from 'react-redux'
class App extends React.Component {
  render () {
    const {num, eat, hungry , eatAsync} = this.props
    return (
      <div className='App'>
        <header className='App-header'>
          <img src={logo} className='App-logo' alt='logo' />
          <p>
            【redux完全指南】系列1：从入门到会用
            <br></br>
            hi gusy， I am stark
          </p>
          <a
            className='App-link'
            href='https://shudong.wang'
            target='_blank'
            rel='noopener noreferrer'>跟着stark wang 学redux</a>
          <h2>stark wang 当前的体重为{num}斤</h2>
          <button onClick={() => {eat()}}>
            吃了一坨山珍海味
          </button>
          <button onClick={() => {eatAsync()}}>
            等了一会，吃了一个煎饼
          </button>
          <button onClick={() => {hungry()}}>
            饿了一天
          </button>
        </header>
      </div>
    )
  }
}
// const mapStateToProps = (state)=>{
//   return {num:state}
// }
// const actionCreators = {eat,hungry}
export default connect((state)=>{
  return {num:state}
},{eat,hungry,eatAsync})(App)

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
import { createStore, applyMiddleware } from 'redux'
import { weight } from './stark.redux'
import { Provider } from 'react-redux'
import thunk from 'redux-thunk'
const store = createStore(weight, applyMiddleware(thunk))
// const render = () =>{
ReactDOM.render(
    <Provider store={store}>
        <App />
    </Provider>,
    document.getElementById('root')
);
// }
// render()
// store.subscribe(render)
// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers: https://bit.ly/CRA-PWA
serviceWorker.unregister();