Redux是一種解決資料共享的方案
import {createStore} from 'redux';
import React from 'react';
import ReactDOM from 'react-dom';
import {connect, createProvider} from 'react-redux'
// data
let allNum = {num :1000}
// 建立reducer, 名字的預設值為
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
}
}
// 建立store存儲資料(傳入處理函數reducer, 核心資料allNum)
let store = createStore(reducer, allNum)
console.log("初始化的資料為",store.getState('num'))
// 添加監聽函數
store.subscribe(() => {console.log("監聽函數發出:", store.getState())});
// 發出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元件, 有兩個資料集,
props
state
-
props
-
state
- 我們可以把多個React元件的
props
元件如何讀寫資料
元件通過action發送信号, reducer處理action, story内的值被reducer修改, 由于React元件已經被綁定到story中, 是以story内的資料被修改後, 可以直接同步到React的元件中
小案例: 實作一個組合計數器
- 單個計數器的資料由元件自身state管理
- 三個計數器的資料隻和由Redux管理
動圖示範
- 實作的源碼如下
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">計數器</p>
<Counter id = "0" />
<Counter id = "1" />
<Counter id = "2" />
<p className="result"> 元件值的和為: { 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> )
}
}
// 建立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
})
// 建立store
let store = createStore(reducer)
// connect連接配接
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);
}
}
}
小結
redux的設計思想是很簡單的, 也有了很成熟的庫函數供我們調用, 是以面對一個問題時, 我們考慮的重點是: React元件内哪些資料需要被Redux管理?把重點問題考慮清楚, 問題也就解決了大半!
為便于管理, 相關資源整合到一張獨立的文章，連結如下: http://www.jianshu.com/p/4f28e1ae08b1
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