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zpao/building-react-from-scratch
Code for my React Rally talk.
Conference talk code from React Rally 2016 where a React core contributor walked through a simplified React implementation called Dilithium. It exists to explain how React worked internally — reconciliation, component lifecycle, DOM diffing — not to be used in production. This is a learning artifact, not a library.
The source is split into the same conceptual pieces as real React (Reconciler, ChildReconciler, Mount, UpdateQueue), so reading it alongside the actual React source gives you a genuine mental model of the architecture. Written by someone on the React team, so the abstractions aren't guesses. The talk video is still available and pairs directly with the code. Small enough to read in an afternoon.
Frozen at React 15 internals — Fiber (React 16) rewrote the reconciler completely, so this code describes an architecture that no longer exists in production React. No tests anywhere. Not maintained — last commit is 2017. Anyone trying to understand modern React hooks, concurrent mode, or the scheduler will need to look elsewhere.