初步了解redux

 1 class Index extends React.Component{
 2     render() {
 3         return (
 4             <React.Fragment>
 5                 <Provider>
 6                     <App/>
 7                 </Provider>
 8             </React.Fragment>
 9         );
10     }
11 }
12 
13 ReactDOM.render(<Index />, document.getElementById('root'));

1 <div>计算器:{this.props.state.number}</div>
2 <button onClick={this.incCounter.bind(this)}>+</button>
3 <button onClick={this.decCounter.bind(this)}>-</button>

 1 constructor(){
 2      super()
 3      this.iAmount = 0
 4 }
 5 //将值传递给src/index.js里面的counter
 6 //增值
 7 incCounter(){
 8      this.props.dispatch({type:"INC",amount:++this.iAmount})
 9 }
10 //减值
11 decCounter(){
12     this.props.dispatch({type:"DEC",amount:--this.iAmount})
13 }

 1 function counter(state={number:0},action) {
 2     switch (action.type) {
 3         case "INC":
 4             return{number: action.amount}
 5         case "DEC":
 6             return{number: action.amount}
 7         default:
 8             return state
 9     }
10 }

1 import {createStore，combineReducers} from 'redux'

 1 let reducer=combineReducers(//合并多个函数
 2     {
 3         counter:counter,
 4     }
 5 )
 6 const store=createStore(reducer);
 7 class Index extends React.Component{
 8     render() {
 9        return (
10             <React.Fragment>
11                 <Provider store={store}>
12                     <App/>
13                 </Provider>
14             </React.Fragment>
15          );
16      }
17  }

1 import { connect } from 'react-redux';
2 
3 export default connect((state)=>{
4     return {
5         state: state
6     }
7 })(App);