react-redux笔记
Posted 六月June June
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目录
目录
创建reducer操作并存储全局state -reducer(state,action){return 新state}
入口文件index.js 挂载store，让所有组件共享全局state
UI组件可以：①显示state，②发送action修改state
Redux是专门用于做状态管理的js库，一般与react配合使用，集中管理多个组件共享的状态。
文档：
https://github.com/reactjs/redux
案例页面效果：
案例文件结构：
redux理解图
搭建环境
第一种：react脚手架
npm install -g create-react-app
create-react-app myapp
npm run start
第二种：用webpack配置
npm init -y
npm i babel-loader babel/core @babel/preset-env @babel/preset-react webpack webpack-cli webpack-dev-server -D
npm i react react-dom redux react-redux redux-thunk redux-devtools-extension -S
react项目文件夹结构
node_modules
dist
-main.js 默认出口文件
public 相当于url的根路径
-favicon.cio
-index.html 在浏览器中打开该文件访问整个项目
src
-App.js
-index.js 默认入口文件
-index.css 通用css
package.json
webapck.config,js
创建webpack.config.js文件
module.exports = {
mode:'development',
module: {
rules: [
{
test: /\\.js|jsx$/,
exclude: /(node_modules|bower_components)/ ,
use: {
loader: 'babel-loader',
options: {
presets: ['@babel/env','@babel/react']
}
}
}
]
},
devtool:'inline-source-map',
watch : true
}在package.json中写dev和build命令：
npm run dev运行时构建，借助webpack-dev-server工具：不打包项目，实时监测代码，模拟生产环境的效果
npm run build是webpack打包命令：自动构建src/main.js文件，到dist/all.js文件中
"scripts": {
"test": "echo \\"Error: no test specified\\" && exit 1",
"dev": "npx webpack serve",
"build":"webpack"
},public/index.html中引入webpack-dev-server默认在内存中隐式生成的main.js文件
<body>
<div id="app-container"></div>
<!-- webpack-dev-server 默认在内存中隐式生成一个main.js-->
<!-- npm run dev 后访问localhost:8080-->
<script src="/main.js"></script>
<!-- npm run build 后右键在浏览器打开此文件-->
<!-- <script src="../dist/main.js"></script> -->
</body>
想要项目打包后模拟生产环境：可在cmd中用serve命令
npm i serve -g
将index.html放在dist文件夹下，然后在dist文件夹下cmd命令 输入 serve，就能在localhost:5000打开index.html
<body>
<div id="app-container"></div>
<script src="./main.js"></script>
</body>react-redux代码编写
创建reducer操作并存储全局state -reducer(state,action){return 新state}
根据action改变state，返回新的state
constant.js用于定义action对象中type类型的常量值，目的：便于管理的同时防止程序员单词写错
reducers/compo1.js根据actions/compo1.js 操作并存储组件Compo1对应的state
export const ADD1 = 'add1'
export const REDUCE1 = 'reduce1'
export const ADD2 = 'add2'
export const REDUCE2 = 'reduce2'<--reducers/compo1.js文件-->
import {ADD1, REDUCE1} from "../constant"
const initState = {v1: 0} //初始化状态
export default function countReducer(preState = initState, action) {
const {type, data} = action
switch (type) {
case ADD1:
return {...preState, v1: preState.v1 + data}
case REDUCE1:
return {...preState, v1: preState.v1 - data}
default:
return preState
}
}
<--actions/compo1.js文件-->
import {ADD1, REDUCE1} from "../constant"
//同步action，就是指action的值为Object类型的一般对象
export const add1 = (data) => ({type: ADD1, data})
export const reduce1 = (data) => ({type: REDUCE1, data})
//异步action，就是指action的值为函数,异步action中一般都会调用同步action
export const add1Async = (data, time) => {
return (dispatch) => {
setTimeout(() => {
dispatch(add1(data))
}, time)
}
}reducers/compo2.js根据actions/compo2.js 操作并存储组件Compo2对应的state
<--reducers/compo2.js-->
import {ADD2, REDUCE2} from "../constant"
const initState = {v2: 0} //初始化状态
export default function countReducer(preState = initState, action) {
const {type, data} = action
switch (type) {
case ADD2:
return {...preState, v2: preState.v2 + data}
case REDUCE2:
return {...preState, v2: preState.v2 - data}
default:
return preState
}
}
<--actions/compo2.js 专门为Compo2组件生成action对象-->
import {ADD2, REDUCE2} from "../constant";
//同步action，值为Object类型
export const add2 = (data) => ({type: ADD2, data});
export const reduce2 = (data) => ({type: REDUCE2, data});
//异步action，值为函数,一般都会调用同步action。
export const add2Async = (data, time) => {
return (dispatch) => {
setTimeout(() => {
dispatch(add2(data));
}, time);
};
};
reducers/index.js汇总reducer
import { combineReducers } from 'redux'
// 引入reducer
import compo1 from './compo1'
import compo2 from './compo2'
//汇总所有的reducer
export default combineReducers({
compo1,
compo2
})
store.js 引入reducer集中管理全局state
import {createStore, applyMiddleware} from "redux"
//引入redux-thunk，用于支持异步action
import thunk from "redux-thunk"
//引入redux-devtools-extension
import {composeWithDevTools} from "redux-devtools-extension"
//汇总后的reducer
import reducer from "./reducers"
export default createStore(reducer, composeWithDevTools(applyMiddleware(thunk)))入口文件index.js 挂载store，让所有组件共享全局state
import React from "react"
import ReactDOM from "react-dom"
import App from "./App"
import store from "./redux/store"
import {Provider} from "react-redux"
console.log(store)
ReactDOM.render(
//Provider要求是最大的组件，通过属性将store往下传
<Provider store={store}>
<App />
</Provider>,
document.getElementById("app-container")
)
App组件挂载UI组件
import React from "react";
import { PropTypes } from "prop-types";
import "./App.css"
import Compo1 from "./component/Compo1";
import Compo2 from "./component/Compo2";
class App extends React.Component{
render() {
return (
<div className="app">App组件
<Compo1 />
<Compo2 />
</div>
)
}
}
export default App;UI组件可以：①显示state，②发送action修改state
Compo1/index.js
import React from "react"
//链接UI组件和redux
import {connect} from "react-redux"
//引入组件1的actions,操作组件1维护的全局state
import {add1, reduce1, add1Async} from "../../redux/actions/compo1"
class Compo1 extends React.Component {
render() {
return (
<div>
<h2>Compo1组件,v1：{this.props.v1}，v2：{this.props.v2}</h2>
<button onClick={() => this.props.add1(2)}>操作v1，+2</button>
<button onClick={() => this.props.reduce1(2)}>操作v1，-2</button>
<button onClick={() => this.props.add1Async(2, 1000)}>
操作v1，异步+2
</button>
</div>
)
}
}
// state数据
const mapStateToProps = (state) => ({
v1: state.compo1.v1,
v2: state.compo2.v2,
})
// actions方法
const mapDispatchToProps = {add1, reduce1, add1Async}
//接收全局state需要connect一下。一般map生成的组件不需要connect，因为不需要看见全局state
// connet()函数中两个参数函数返回的json中的k会自动成为props中的对象
// 组件中就可以通过this.props访问state数据和使用action方法了
export default connect(mapStateToProps, mapDispatchToProps)(Compo1)
Compo2/index.js
import React from "react"
//链接UI组件和redux
import {connect} from "react-redux"
//引入actions,操作全局state
import {add2, reduce2} from "../../redux/actions/compo2"
class Compo2 extends React.Component {
render() {
console.log(this.props)
return (
<div>
<h2>Compo2组件,v1：{this.props.v1}，v2：{this.props.v2}</h2>
<button onClick={() => this.props.add2(2)}>操作v2，+2</button>
<button onClick={() => this.props.reduce2(2)}>操作v2，-2</button>
</div>
)
}
}
const mapStateToProps = (state) => ({
v1: state.compo1.v1,
v2: state.compo2.v2,
})
const mapDispatchToProps = {add2, reduce2}
export default connect(mapStateToProps, mapDispatchToProps)(Compo2)
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