React全局状态管理

? ? ? ? ? redux是一个状态管理框架，它可以帮助我们清晰定义state和处理函数，提高可读性，并且redux中的状态是全局共享，规避组件间通过props传递状态等操作。

快速使用

? ????????在React应用的根节点，需要借助React的Context机制存放整个store信息。需要进行以下配置。

index.js

import React from 'react'
import ReactDOM from 'react-dom'

import {Provider} from 'react-redux'
import {store} from './store'
import App from './app'

const rootElement = document.getElementById('root');

ReactDOM.render(
    <Provider store = {store}>
        <App/>
    </Provider>,
    
    rootElement
    
)

? ? ? ? store文件需要配置下Redux，包括reducer和action以及state

store.js

import {createStore} from 'redux'


const initialState = {value: 0}


// Reducer
function counterReducer(state = initialState, action){
    switch (action.type){
        case 'counter/incremented':
            return {value: state.value + 1};
        case 'counter/decremented':
            return {value: state.value - 1};
        default:
            return state
    }
}

// Action
export const incrementAction = {type:'counter/incremented'}
export const decrementAction = {type: 'counter/decremented'}

// Redux 定义
export const store = createStore(counterReducer)

在业务逻辑中，需要通过useSelector和useDispatch自定义hook获取state和dispatch

Counter.js

import React from 'react'
import {useDispatch, useSelector} from 'react-redux'
import {decrementAction, incrementAction} from "./store";

export function Counter() {

    const count = useSelector(state => state.value)

    const dispatch = useDispatch()

    return (
        <div>
            <button onClick={() => dispatch(incrementAction)}>
                +
            </button>
            <span>{count}</span>
            <button onClick={() => dispatch(decrementAction)}>
                -
            </button>
        </div>

    )

}

使用效果