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這篇文章給大家介紹使用Redux怎么實(shí)現(xiàn)一個(gè)組合計(jì)數(shù)器,內(nèi)容非常詳細(xì),感興趣的小伙伴們可以參考借鑒,希望對(duì)大家能有所幫助。
Redux是一種解決數(shù)據(jù)共享的方案
import {createStore} from 'redux'; import React from 'react'; import ReactDOM from 'react-dom'; import {connect, createProvider} from 'react-redux' // data let allNum = {num :1000} // 創(chuàng)建reducer, 名字的默認(rèn)值為 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 } } // 創(chuàng)建store存儲(chǔ)數(shù)據(jù)(傳入處理函數(shù)reducer, 核心數(shù)據(jù)allNum) let store = createStore(reducer, allNum) console.log("初始化的數(shù)據(jù)為",store.getState('num')) // 添加監(jiān)聽函數(shù) store.subscribe(() => {console.log("監(jiān)聽函數(shù)發(fā)出:", store.getState())}); // 發(fā)出action let 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組合使用
React組件, 有兩個(gè)數(shù)據(jù)集, props和state
props表示外部傳入組件的參數(shù)(數(shù)據(jù)由外部傳入, 可以被外部更改)
state表示組件固有的屬性(數(shù)據(jù)私有, 不可以被外部更改)
我們可以把多個(gè)React組件的props交由Redux進(jìn)行管理, 這樣就實(shí)現(xiàn)了React組件之間數(shù)據(jù)的共享
組件如何讀寫數(shù)據(jù)
組件通過action發(fā)送信號(hào), reducer處理action, story內(nèi)的值被reducer修改, 由于React組件已經(jīng)被綁定到story中, 所以story內(nèi)的數(shù)據(jù)被修改后, 可以直接同步到React的組件中
小案例: 實(shí)現(xiàn)一個(gè)組合計(jì)數(shù)器
單個(gè)計(jì)數(shù)器的數(shù)據(jù)由組件自身state管理
三個(gè)計(jì)數(shù)器的數(shù)據(jù)只和由Redux管理
動(dòng)圖演示
實(shí)現(xiàn)的源碼如下
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">計(jì)數(shù)器</p> <Counter id = "0" /> <Counter id = "1" /> <Counter id = "2" /> <p className="result"> 組件值的和為: { 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 = "減1" onClick = { this.decrease }/> <span > { value } < /span><br/ > <input type = "button" value = "加1" onClick = { this.increase }/> </div> ) } } // 創(chuàng)建reducer function 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 }) // 創(chuàng)建store let store = createStore(reducer) // connect連接 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); } } }
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