Example app created by Mauricio Dinarte (@dinarcon) to explain React JS concepts.
You need to serve the files from a web server. Any language's built-in server will work. Open the terminal, change directory into the app's code, and run the web server. Below are some alternatives for different languages:
php -S localhost:5500
Then open your browser at http://localhost:5500/
Using the React Dev Tools extension for your browser is highly recommended.