In an impressive blog post on his blog, React lead developer Dan Abramov, explains how React works on the hood.

This is a deep dive — THIS IS NOT a beginner-friendly post. In this post, I’m describing most of the React programming model from first principles. I don’t explain how to use it — just how it works. It’s aimed at experienced programmers and folks working on other UI libraries who asked about some tradeoffs chosen in React. I hope you’ll find it useful!

React as a UI Runtime