[React.js] state

www.inflearn.com/course/react-%EA%B0%95%EC%A2%8C-velopert/lecture/4143?tab=curriculum

 

html

<div id="root"></div>

js

class Counter extends React.Component{
  constructor(props){
    super(props);
    this.state = {
      value:0
    };
    this.handleClick = this.handleClick.bind(this);
  }
  
  handleClick(){
      this.setState({
        value: this.state.value + 1
      });
    {/*
    아래 소스는 좋지 않음.
    this.state.value = this.state.valu +1;
    this.forceUpdate();
    */}
  }
  render(){
    return(
      <div>
        <h2>{this.state.value}</h2>
        <button onClick={this.handleClick}>Press Me</button>   {/*this.handleClick()  << 렌더링을 계속하게되서 오류 발생 */}
      </div>
    )
  }
}
 
class App extends React.Component {
  render() {
    return (
      <Counter/>
    );
  }
};
 
ReactDOM.render(
  <App></App>,
  document.getElementById("root")
);