import React from 'react';
import ReactDOM from 'react-dom';

document.addEventListener('DOMContentLoaded', function(){

    class Click extends React.Component {

      handleClick = () => {
        console.log('działa')
      }


      render() {
        return(
          <button onClick={this.handleClick}>Klik!</button>
        )
      }
    }

    ReactDOM.render(
        <Click />,
        document.getElementById('app')
    );
});