05 React修改值使用setState,获取值this.state.xxx

    state = {
        num: 10
    }

 通过 this.setState({
      num:this.state.num+12
  })

import React, { Component } from "react"; 
 export default class StaTest extends Component {
    state={
        nun:1
    }
    render(){
        return <div>
            {/* 获取state中的值 */}
            {this.state.nun}
        </div>
    }
  }
import StaTest from "./components/StaTest"
  {/* 使用 */}
  <StaTest></StaTest>