React16, 18 uses Redux

Redux Core

Introduction to Redux

Redux is a JavaScript state container that provides predictable state management.

Redux workflow

Actions: Object, describing how to operate on the state

Reducer: function, operates on state and returns new state

Store: container for storing state, JavaScript object

View: view, HTML page

React 16 uses Redux

Install

npm install --save redux

Create a store warehouse

srcCreate a storefolder under the directory, and then create a file under the index.jsfolder

import { legacy_createStore as createStore } from "redux";
import reducer from "./reducer";

const store = createStore(reducer, window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__()) // 创建数据存储仓库

export default store

Create a file under storethe folderreducer.js

const defaultstate = {
    list: [1,2,3,4,5,6],
    inpuValue: ''
}

export default (state = defaultstate) => {
    return state;
}

use in the page

srcCreate TodoList.jsa page in the directory

in constructorthe introduction

this.state=store.getState();

use

this.state.list

dispatchModify the value inside by

store.dispatch({
   type: 'changeList',
   value: newList
})

reducer.jsAdd the corresponding method in

const defaultstate = {
    list: [1,2,3,4,5,6],
    inpuValue: ''
}

export default (state = defaultstate, action) => {
    switch(action.type) {
        case "changeList":
            return {
                ...state,
                list: action.value
            }
        default:
            return state;
    }
}

constructorAdd subscription status to Redux

this.storeChange = this.storeChange.bind(this) 
store.subscribe(this.storeChange) 

writing storeChangemethod

storeChange(){
    this.setState(store.getState())
}

Complete code

import React, { Component } from 'react';
import store from './store'

class TodoList extends Component {
	 constructor(props){
     super(props)
     this.state=store.getState();
     this.storeChange = this.storeChange.bind(this)
		 store.subscribe(this.storeChange) 
	 }
	 
	 handleChange(){
			this.setState({
        inputValue:this.inputRef.value
    	})
   }
   
   handleAdd() {
   		let newList = this.state.list
      newList.push(this.inputRef.value)
      store.dispatch({
          type: 'changeList',
          value: newList
      })
      this.setState({
        inputValue: ''
    	})
   }
   
   handledel(index) {
   		const list = this.state.list
      list.splice(index, 1)
      store.dispatch({
          type: 'changeList',
          value: list
      })
   }
   
   storeChange(){
     this.setState(store.getState())
   }
	 
   render() { 
        return ( 
            <div>
            	<div>
                <input ref={(inputRef)=>{this.inputRef=inputRef}} value={this.state.inputValue} onChange={handleChange.bind(this)} />
                <button onClick={handleAdd.bind(this)}>新增</button>
            	</div>
            	{this.state.list.map((item, index) => {
       					 return (<div key={index}><p>{item}<span onClick={() => handledel(index).bind(this)}> 删除</span></p></div>)
    					})}
        	</div>
         );
    }
}

export default TodoList;

React 18 uses Redux

Installation and creation of warehouse are the same as in 16

use

Import normally and use a variable to receive

import store from './store'

const state = store.getState()

When using it, you can use it directly by state.xxx

    const items = state.list.map((item, index) => {
        return (<div key={index}><p>{item}<span onClick={() => handledel(index)}> 删除</span></p></div>)
    })

Revise

Same as dispatch

store.dispatch({
    type: 'changeList',
    value: list
})

In order for the page to update in real time, it must be updated manually

Use reactthe built-in useEffectmethod to subscribe monitor the store update function

useEffect(() => {
        // store.subscribe()是redux提供的，监测store更新的函数
        store.subscribe(() => {
            // 当store数据更新后执行 setUpdate() ，组件重新加载，实现界面store数据更新
            setUpdate({})
        })
    })

const [update,setUpdate] = useState({})

Complete code

import React, { useRef, useState, startTransition, useEffect } from 'react';
import store from './store'

const TotoList = () => {
    const inputRef = useRef()

    const state = store.getState()

    const [update,setUpdate] = useState({})

    const [value, setValue] = useState('')

    const items = state.list.map((item, index) => {
        return (<div key={index}><p>{item}<span onClick={() => handledel(index)}> 删除</span></p></div>)
    })

    const handleChange = () => {
        startTransition(()=> {
            setValue(inputRef.current.value)
        })
    }

    const handleAdd = () => {
        let newList = state.list
        newList.push(inputRef.current.value)
        store.dispatch({
            type: 'changeList',
            value: newList
        })
        setValue('')
    }

    const handledel = (key) => {
        const list = state.list
        list.splice(key, 1)
        store.dispatch({
            type: 'changeList',
            value: list
        })
    }


    useEffect(() => {
        // store.subscribe()是redux提供的，监测store更新的函数
        store.subscribe(() => {
            // 当store数据更新后执行 setUpdate() ，组件重新加载，实现界面store数据更新
            setUpdate({})
        })
    })

    return (
        <div>
            <div>
                <input ref={inputRef} value={value} onChange={handleChange} />
                <button onClick={handleAdd}>新增</button>
            </div>
            {items}
        </div>
    )
}

export default TotoList;