原生实现一个react-redux的代码示例

├─component
│ connect.js
│ counter.js
│
└─store
 index.js

import React from "react";
import ReactDom,{render} from "react-dom";
import Couter from "./component/counter";
import {Provider} from "./component/connect" import store from "./store/index" ReactDom.render(<Provider store={store}><Couter/></Provider>,document.getElementById("root"));

import {createStore} from "redux";
function reducer(state={number:0},action) {
 switch (action.type){
 case "add":
 return {number:state.number+action.count}
 default:
 return state;
 }
}

export default createStore(reducer);

import React from "react";
import PropTypes from "prop-types";
//Provider是一个组件 接受一个store属性 将其内容挂载在上下文context //这样后代才可以都有办法拿到 class Provider extends React.Component{

 static childContextTypes={
 //设置上下文的类型是对象
 store:PropTypes.object
 }

 getChildContext(){
 //获取并设置后代上下文的内容
 return {store:this.props.store}
 }
 render(){
 return this.props.children
 }
}

let connect=(mapStateToProps,mapDispatchToProps)=>(comp)=>{
 return class Proxy extends React.Component{
 static contextTypes={
 store:PropTypes.object
 }
 constructor(props,context){
 super(props);
 //将参数mapStateToProps 的解构赋值 代理组件的状态
 this.setState=mapStateToProps(context.store.getState())
 }
 componentDidMount(){
 this.context.store.subscribe(()=>{
 this.setState(mapStateToProps(this.context.store.getState()))
 })
 }
 render(){
 return <comp {...this.state} {...mapDispatchToProps(this.context.store.dispatch)}/>
 }
 }
}

export {Provider,connect}

import React from "react";
import {connect} from "./connect";
export default class Counter extends React.Component{
 constructor(props){
 super(props);
 }

 render(){
 return (
 <div>
 <button onClick={()=>{
 this.props.add(5);
 }}>+</button>
 {this.props.n}
 </div>
 )
 }
}

let mapStateToProps=(state)=>{
 return {n:state.number}
};
let mapDispatchToProps=(dispatch)=>{
 return {
 add:(count)=>{
 dispatch({type:"add",count:count})
 }
 }
}

export default connect(mapStateToProps,mapDispatchToProps)(Counter)