日本免费高清视频-国产福利视频导航-黄色在线播放国产-天天操天天操天天操天天操|www.shdianci.com

學無先后，達者為師

網站首頁 編程語言 正文

React使用redux基礎操作詳解_React

作者：web老猴子 ? 更新時間： 2023-03-04 編程語言

一，什么是redux

Redux是一個用來管理管理數據狀態和UI狀態的JavaScript應用工具。隨著JavaScript單頁應用（SPA）開發日趨復雜，JavaScript需要管理比任何時候都要多的state（狀態），Redux就是降低管理難度的。（Redux支持React，Angular、jQuery甚至純JavaScript） react-redux工作流程 安裝redux

npm install --save redux

簡單使用

在src下新建store文件夾，創建倉庫管理文件index.js

import { createStore, applyMiddleware, compose } from 'redux'  // 引入createStore方法
import reducer from "./reducer"
const store = createStore(reducer) // 創建數據存儲倉庫
export default store                 //暴露出去

同時創建reducer.js文件

//定義初始state
const defaultState = {
  inputValue: '請輸入待辦事項',
  list: [
    '早上4點起床，鍛煉身體',
    '中午下班游泳一小時']
}
export default (state = defaultState, action) => {
  return state
}

組件中使用state的值

import React, { Component } from 'react';
//組件中引入store
import store from './store'
class TodoList extends Component {
  constructor(props) {
    super(props)
    #獲取store中state的值
    this.state = store.getState();
    this.clickBtn = this.clickBtn.bind(this)
?}
  render() {
    return (
           <div>
                <Input placeholder={this.state.inputValue} style={{ width: '250px', marginRight: '10px' }}  value={this.state.inputValue} />
                <Button type="primary" onClick={clickBtn}>增加</Button>
            </div>
            <div style={{ margin: '10px', width: '300px' }}>
                <List bordered
                    dataSource={this.state.list}
                    renderItem={(item, index) => (<List.Item onClick={() => {
                       deleteItem(index)
                  }}>{item}</List.Item>)}></List>
            </div>
  );}deleteItem(index) {console.log(index)}
}
export default TodoList;

二，安裝redux谷歌調試工具

翻墻下載redux_dev_tool, 在store/index文件下添加

import { createStore, applyMiddleware, compose } from 'redux'  // 引入createStore方法
import reducer from "./reducer"
//const composeEnhancers = 
//const enhancers = composeEnhancers(applyMiddleware(thunk)) 
const store = createStore(
                           reducer,
                           window.__REDUX_DEVTOOLS_EXTENSION_ && window.__REDUX_DEVTOOLS_EXTENSION_()
                         ) // 創建數據存儲倉庫,存在調試工具，開啟工具
export default store

三，操作store 改變

import React, { Component } from 'react';
//組件中引入store
import store from './store'
class TodoList extends Component {
  constructor(props) {
    super(props)
    #獲取store中state的值
    this.state = store.getState();
    this.clickBtn = this.clickBtn.bind(this)this.changeInputValue = this.changeInputValue.bind(this)
    #添加訂閱 #新版本不用添加訂閱 但是input value變化需要使用訂閱
    store.subscribe(this.storeChange)
    this.storeChange = this.storeChange.bind(this)}
  render() {
    return (
           <div>
                <Input placeholder={this.state.inputValue} style={{ width: '250px', marginRight: '10px' }} onChange={()=>{this.changeInputValue}  value={this.state.inputValue} />
                <Button type="primary" onClick={this.clickBtn}>增加</Button>
            </div>
            <div style={{ margin: '10px', width: '300px' }}>
                <List bordered
                    dataSource={this.state.list}
                    renderItem={(item, index) => (
                      <List.Item onClick={() => {deleteItem(index)}}>{item}</List.Item>)}></List>
            </div>
  );}changeInputValue(e){//聲明action對象
    const action ={
  type:'changeInput',
      value:e.target.value
  }
    //調用dispatch
    store.dispatch(action)}
  // 訂閱更新
  storeChange() {
    this.setState(store.getState())}// 添加按鈕事件clickBtn(){const action ={
  type:'addItem',
  }store.dispatch(action)}//點擊刪除事件deleteItem(index) {
    const action = {
  type:'deleteItem',
      index
  }
    store.dispatch(action)}
}
export default TodoList;

在reducer.js中

//定義初始state
const defaultState = {
  inputValue: '請輸入待辦事項',
  list: [
    '早上4點起床，鍛煉身體',
    '中午下班游泳一小時']
}
export default (state = defaultState, action) => {
  #reducer里只能接受state 不能改變state
  if(action.type == 'changeInput'){
    let newState = JSON.pares(JSON.stringify(state)) //深拷貝state
    newState.inputValue = action.value
    return newState}
  //添加事件
  if(action.type == 'addItem'){
    let newState = JSON.pares(JSON.stringify(state)) //深拷貝state
    newState.list.push(newState.inputValue)
    newState.inputValue = '' //增加完成，設置為空
    return newState}
  //刪除事件
  if(action.type == 'deleteItem'){
    let newState = JSON.pares(JSON.stringify(state)) //深拷貝state
    newState.list.splice(action.index,1)
    return newState}
  return state
}

四，寫redux的小技巧

在store中新建文件actionType.js

//定義常量
export const CHANGE_INPUT = 'changeInput'
export const ADD_ITEM = 'addItem'
export const DELETE_ITEM = 'deleteItem'
export const GET_LIST = 'getList'

在組件中引入actionType文件

import React, { Component } from 'react';
//組件中引入store
import store from './store'
import { CHANGE_INPUT, ADD_ITEM, DELETE_ITEM, GET_LIST } from './store/actionType'
class TodoList extends Component {
  constructor(props) {
    super(props)
    #獲取store中state的值
    this.state = store.getState();
    this.clickBtn = this.clickBtn.bind(this)this.changeInputValue = this.changeInputValue.bind(this)
    #添加訂閱 #新版本不用添加訂閱 但是input value變化需要使用訂閱
    store.subscribe(this.storeChange)
    this.storeChange = this.storeChange.bind(this)}
  render() {
    return (
           <div>
                <Input placeholder={this.state.inputValue} style={{ width: '250px', marginRight: '10px' }} onChange={()=>{this.changeInputValue}  value={this.state.inputValue} />
                <Button type="primary" onClick={this.clickBtn}>增加</Button>
            </div>
            <div style={{ margin: '10px', width: '300px' }}>
                <List bordered
                    dataSource={this.state.list}
                    renderItem={(item, index) => (
                      <List.Item onClick={() => {deleteItem(index)}}>{item}</List.Item>)}></List>
            </div>
  );}changeInputValue(e){//聲明action對象
    #使用引入的常量替換
    const action ={
  type:CHANGE_INPUT,
      value:e.target.value
  }
    //調用dispatch
    store.dispatch(action)}
  // 訂閱更新
  storeChange() {
    this.setState(store.getState())}// 添加按鈕事件clickBtn(){const action ={
  type:ADD_ITEM,
  }store.dispatch(action)}//點擊刪除事件deleteItem(index) {
    const action = {
  type:DELETE_ITEM,
      index
  }
    store.dispatch(action)}
}
export default TodoList;

在reducer.js中也進行引入

import { CHANGE_INPUT, ADD_ITEM, DELETE_ITEM } from './actionType'
//定義初始state
const defaultState = {
  inputValue: '請輸入待辦事項',
  list: [
    '早上4點起床，鍛煉身體',
    '中午下班游泳一小時']
}
export default (state = defaultState, action) => {
  #reducer里只能接受state 不能改變state
  if(action.type == CHANGE_INPUT){
    let newState = JSON.pares(JSON.stringify(state)) //深拷貝state
    newState.inputValue = action.value
    return newState}
  //添加事件
  if(action.type == ADD_ITEM){
    let newState = JSON.pares(JSON.stringify(state)) //深拷貝state
    newState.list.push(newState.inputValue)
    newState.inputValue = '' //增加完成，設置為空
    return newState}
  //刪除事件
  if(action.type == DELETE_ITEM){
    let newState = JSON.pares(JSON.stringify(state)) //深拷貝state
    newState.list.splice(action.index,1)
    return newState}
  return state
}

集中整理action派發

在store中新建actionCreator.js文件

import { CHANGE_INPUT, ADD_ITEM, DELETE_ITEM } from './actionType'
export const changeInputAction = (value) =>({type:CHANGE_INPUT,
  value
})
export const addItemAction = () =>({type:ADD_ITEM,
})
export const deleteItemAction = (index) =>({type:DELETE_ITEM,
  index
})

在組件中引入actionCreator.js

import React, { Component } from 'react';
//組件中引入store
import store from './store'
//引入actionCreator.js
import { changeInputAction,addItemAction,deleteItemAction } from './store/actionCreator'
class TodoList extends Component {
  constructor(props) {
    super(props)
    #獲取store中state的值
    this.state = store.getState();
    this.clickBtn = this.clickBtn.bind(this)this.changeInputValue = this.changeInputValue.bind(this)
    #添加訂閱 #新版本不用添加訂閱 但是input value變化需要使用訂閱
    store.subscribe(this.storeChange)
    this.storeChange = this.storeChange.bind(this)}
  render() {
    return (
           <div>
                <Input placeholder={this.state.inputValue} style={{ width: '250px', marginRight: '10px' }} onChange={()=>{this.changeInputValue}  value={this.state.inputValue} />
                <Button type="primary" onClick={this.clickBtn}>增加</Button>
            </div>
            <div style={{ margin: '10px', width: '300px' }}>
                <List bordered
                    dataSource={this.state.list}
                    renderItem={(item, index) => (
                      <List.Item onClick={() => {deleteItem(index)}}>{item}</List.Item>)}></List>
            </div>
  );}changeInputValue(e){
    const action = changeInputAction(e.target.value)
    //調用dispatch
    store.dispatch(action)}
  // 訂閱更新
  storeChange() {
    this.setState(store.getState())}// 添加按鈕事件clickBtn(){const action =addItemAction()store.dispatch(action)}//點擊刪除事件deleteItem(index) {
    const action = deleteItemAction(index)
    store.dispatch(action)}
}
export default TodoList;

原文鏈接：https://blog.csdn.net/web220507/article/details/128643708

欄目分類
最近更新