Redux是一种解决数据共享的方案
import {createStore} from 'redux';import React from 'react';import ReactDOM from 'react-dom';import {connect, createProvider} from 'react-redux'// datalet allNum = {num :1000}// 创建reducer, 名字的默认值为function reducer(state, action) { let tmp = {} if (action.type == "decrease"){
allNum.num = allNum.num - action.value;
tmp = Object.assign({}, state, {num: allNum.num}) return tmp
}else if(action.type == "increase"){
allNum.num = allNum.num + action.value;
tmp = Object.assign({}, state, {num: allNum.num}) return tmp
}else{ return state
}
}// 创建store存储数据(传入处理函数reducer, 核心数据allNum)let store = createStore(reducer, allNum)console.log("初始化的数据为",store.getState('num'))// 添加监听函数store.subscribe(() => {console.log("监听函数发出:", store.getState())});// 发出actionlet tmp = {};
tmp = store.dispatch({type: "decrease", value: 10})console.log("---->", tmp);
tmp = store.dispatch({type: "decrease", value: 100})console.log("---->", tmp);
tmp = store.dispatch({type: "increase", value: 31})console.log("---->", tmp);
tmp = store.dispatch({type: "increase", value: 123})console.log("---->", tmp);class MyComponent extends React.Component {
render() {return <div>Hello World</div>;}
}
ReactDOM.render(<MyComponent />, document.getElementById("root"));React和Redux组合使用
React组件, 有两个数据集,
props和stateprops表示外部传入组件的参数(数据由外部传入, 可以被外部更改)state表示组件固有的属性(数据私有, 不可以被外部更改)我们可以把多个React组件的
props交由Redux进行管理, 这样就实现了React组件之间数据的共享
组件如何读写数据
组件通过action发送信号, reducer处理action, story内的值被reducer修改, 由于React组件已经被绑定到story中, 所以story内的数据被修改后, 可以直接同步到React的组件中
小案例: 实现一个组合计数器
单个计数器的数据由组件自身state管理
三个计数器的数据只和由Redux管理
动图演示
实现的源码如下
index.html
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>react-webpack-demo</title></head><body> <div id="root"></div></body></html>
index.js
import 'babel-polyfill';
import React from 'react';
import ReactDOM from 'react-dom';
import './index.scss';
import Redux from 'redux';
import { connect, Provider } from 'react-redux';
import { createStore } from 'redux';
import { PropTypes } from 'prop-types';class ManageCounter extends React.Component {
constructor(props) {
super(props);
}
render() { return ( <div>
<p className="title">计数器</p>
<Counter id = "0" />
<Counter id = "1" />
<Counter id = "2" />
<p className="result"> 组件值的和为: { this.props.sum } </p>
</div> )
}
}class Counter extends React.Component {
constructor(props) {
super(props);
this.changeSum = this.changeSum.bind(this)
this.decrease = this.decrease.bind(this)
this.increase = this.increase.bind(this)
this.state = { value: 0 };
}
changeSum() {
this.props.dispatch({ type: 'changeSum', payload: { id: this.props.id, value: this.state.value } })
}
decrease() {
let self = this;
this.setState({ value: this.state.value - 1 }, () => { self.changeSum()
})
}
increase() {
let self = this; self.setState({ value: this.state.value + 1 }, () => { self.changeSum()
})
}
render() { const { value } = this.state;
let { id } = this.props; return ( <div >
<input type = "button"value = "减1" onClick = { this.decrease }/>
<span > { value } < /span><br/ >
<input type = "button" value = "加1" onClick = { this.increase }/>
</div> )
}
}// 创建reducerfunction reducer(state = { number: [0, 0, 0], sum: 0 }, action = {}) { if (action.type == 'changeSum') {
let { id, value } = action.payload
console.log("id:", id, "value:", value);
state.number[id] = value
let tmpSum = 0; for (let i = 0; i < state.number.length; i++) {
tmpSum += state.number[i]
} return Object.assign({}, state, { sum: tmpSum });
} else { return state;
}
}const CounterMapStateToProps = (state) => ({
})const ManageCounterMapStateToProps = (state) => ({
sum: state.sum
})const mapDispatchToProps = (dispatch) => ({
dispatch: dispatch
})// 创建storelet store = createStore(reducer)// connect连接Counter = connect(CounterMapStateToProps, mapDispatchToProps)(Counter)
ManageCounter = connect(ManageCounterMapStateToProps, mapDispatchToProps)(ManageCounter)
ReactDOM.render(
<Provider store = { store }>
<ManageCounter />
</Provider> ,
document.getElementById('root'));index.scss
$designWidth: 750;
@function px2rem($px) {
@return $px*10/$designWidth+rem;
}#root {
div {
p {
font-size: px2rem(300);
color: #5EA1F3;
text-align: center;
}
div {
font-size: px2rem(500);
display: flex;
color: #64B587;
border: 1px solid #F0BB40;
input {
flex: 1 1 auto;
background-color: #64B587;
font-size: px2rem(200);
outline: none;
color:#ffffff;
}
span {
width: 300px;
flex: 1 1 auto;
text-align: center;
}
}
.title {
color: #BDBDBD;
}
.result {
font-size: px2rem(200);
}
}
}小结
redux的设计思想是很简单的, 也有了很成熟的库函数供我们调用, 所以面对一个问题时, 我们考虑的重点是: React组件内哪些数据需要被Redux管理?把重点问题考虑清楚, 问题也就解决了大半!
作者：木子昭
链接：https://www.jianshu.com/p/bf3231af3906
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