zadanie04.jsx

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

document.addEventListener('DOMContentLoaded', function(){
    class CrazyDiv extends React.Component {
        constructor(props){
            super(props);

            this.state = {
                left  : '0',
                top: '0',
            };
        }

        handleDivMouseMove = () => {
            const top = Math.round( Math.random() * 1000 ) + 'px';
            const left = Math.round( Math.random() * 1000 ) + 'px';

            this.setState({
                top,
                left,
            });
        };

        render(){
            return <div style={{
                width           :   '100px',
                height          :   '100px',
                position        :   'absolute',
                backgroundColor :   'red',
                left            :   this.state.left,
                top             :   this.state.top
            }}
                onMouseEnter={this.handleDivMouseMove}
            />;
        }
    }

    class App extends React.Component {
        render(){
            return <CrazyDiv />;
        }
    }

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