import { Beforeunload } from 'react-beforeunload';

class Example extends React.Component {
  state = { value: '' };

  render() {
    return (
      <>
        {value !== '' && (
           event.preventDefault()} />
        )}
         this.setState({ value: event.target.value })}
          value={this.state.value}
        />
      
    );
  }
}