How to troubleshoot issues with virtual DOM concepts?

// Example: Using React's Virtual DOM
import React from 'react';
import ReactDOM from 'react-dom';

class App extends React.Component {
    constructor(props) {
        super(props);
        this.state = { count: 0 };
    }

    increment = () => {
        this.setState({ count: this.state.count + 1 });
    }

    render() {
        return (
            

                
Count: {this.state.count}
                Increment
            
        );
    }
}

ReactDOM.render(, document.getElementById('root'));