I'm the author of this post, happy to answer any questions :)
You can see my code here: https://github.com/samwho/visualisations
Web components are just one method of componentising the visualisations. I'm steering clear of React/Vue/whatever other framework because I want these posts to still be relevant in 10 years. I'm not confident any existing frontend framework will be around 10 years from now, so decided to stick to web standards.