ref.html

web-cheat/react/ref.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>ref</title>
<script src="https://unpkg.com/react@17/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@17/umd/react-dom.development.js"></script>
<script src="https://unpkg.com/@babel/standalone@7.14.7/babel.min.js"></script>
</head>
<body>
<div id="root"></div>
<script type="text/babel">
class ContentRenderer extends React.Component {
  constructor(props) {
    super(props);
    this.state = {n: 0};
    this.handleClick = this.handleClick.bind(this);
  }

  componentDidMount() {
    this.myElement.addEventListener('click', (e) => {
      alert(1);
    });
  }

  componentWillUnmount() {
    this.observer.disconnect();
  }

  handleClick() {
    this.setState((state, props) => ({
        n: state.n + 1
    }));
  }

  render() {
    return (
      <div>
        <div onClick={this.handleClick}>Click me</div>
        <div
          dangerouslySetInnerHTML={{ __html: "<b>" + this.state.n + "</b>" }}
          ref={(myElement) => { this.myElement = myElement; }}
        />
      </div>
    );
  }
}

ReactDOM.render(
  <ContentRenderer/>,
  document.getElementById('root')
);
</script>
</body>
</html>