App.js ���ڪ� �m2۪� import React from 'react' export class Appp extends React.Component{ constructor(props) { super(props) this.state = { counter: 0 } } change(e) { console.log(e.target.value) console.log(this.refs) this.setState({ counter: e.target.value }) } incrementCounter() { var counter = this.state.counter + 1 this.setState({ counter: counter }) } render() { return ( <div> <span>{this.state.