一文搞懂redux在react中的初步用法

import React, { Component, Fragment } from 'react';

//Class引入
import { connect } from 'react-redux';

//Hook引入
import { useSelector, useDispatch } from 'react-redux'

import { add, clear } from '../../redux/actions/count';


//hook 展示组件
const CountItem = (props) => {
    // 解构出来
    const {
        count,
        flag,
        add,
        clear
    } = props
    return (
        <>
            <h2>当前求和为：{count}</h2>
            <h3>当前Flag：{flag ? 'true' : 'false'}</h3>
            <button onClick={add}>点击+1</button>
            <button onClick={clear}>清零</button>
        </>
    )
}

//hook 容器组件
const Count = () => {
    const count = useSelector(state => state.sum)
    const flag = useSelector(state => state.flag)
    const dispatch = useDispatch()

    const countAdd = () => {
        console.log(add.type)
        dispatch(add(1))
    }

    const clearNum = () => {
        dispatch(clear())
    }

    return <CountItem count={count} flag={flag} add={countAdd} clear={clearNum}  />
}

export default Count



// class 展示组件
// class Count extends Component {
//     add = () => {
//         // 通知redux
//         this.props.add(1);
//     };
//     clear = () => {
//         this.props.clear();
//     };
//     render() {
//         return (
//             <Fragment>
//                 <h2>当前求和为：{this.props.count}</h2>
//                 <h3>当前Flag：{this.props.flag ? 'true' : 'false'}</h3>
//                 <button onClick={this.add}>点击+1</button>
//                 <button onClick={this.clear}>清零</button>
//             </Fragment>
//         );
//     }
// }

// class 容器组件
// export default connect(
//     // 1.状态
//     state => ({ count: state.sum, flag: state.flagState }),
//     // 2.方法
//     { add, clear }
// )(Count);

// 为Count组件创建action对象
// 引入常量
import { ADD, CLEAR } from '../constant';

// 创建加一action对象的函数
export const add = data => ({
    type: ADD,
    data,
});

// 创建清零action对象的函数
export const clear = data => ({
    type: CLEAR,
    data,
});

export const ADD = 'add';
export const CLEAR = 'clear';

// 为Count组件创建一个reducer
// reducer接收两个参数：之前状态的preState，动作对象action

import { ADD, CLEAR } from '../constant.js';

// 设定初始状态
const initState = 0;

export default function addReducer(preState = initState, action) {
    // 从action中获取type和data
    const { type, data } = action;
    // 根据type决定如何加工数据
    switch (type) {
        case ADD:
            return preState + data;
        case CLEAR:
            return 0;
        // 初始化动作
        default:
            return preState;
    }
}

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App.jsx';
import store from './redux/store';
import { Provider } from 'react-redux';

ReactDOM.render(
    // Provider包裹App，目的：让App所有的后代容器组件都能接收到store
    <Provider store={store}>
        <App />
    </Provider>,
    document.getElementById('root')
);

// 整个文档只有一个store对象，createStore接收两个参数，第一个是state树，第二个是要处理的action
//applyMiddleware 汇总所有的中间件变成一个数组依次执行，异步处理
import { createStore, applyMiddleware } from 'redux';
//中间件
import thunk from 'redux-thunk';
//汇总所有的reducer
import allReducers from './reducers/index';
//这里是goole的调试调试工具，具体使用：百度
import { composeWithDevTools } from 'redux-devtools-extension';

// 暴露store
export default createStore(allReducers, composeWithDevTools(applyMiddleware(thunk)));