Poor Man's React

Understanding React by implementing some of its core concepts in a simple manner.

Inspired by Tejas Kumar's talk Deconstructing React.

Essential stuff that is missing:

The ability to have multiple root nodes (currently, it is fixed to render <App /> to document.body)
Re-using DOM nodes (for performance and to prevent loss of focus etc)
Class-based components
Style support
All hooks except useState
Everything else that would make this implementation usable