Toy React

Rebuilding React from scratch to finally understand what's inside.

Started as a follow-along to Build your own React and grew beyond "just adding types."

The goal wasn't to clone all of React – it was to get its core mechanics and design decisions right: fibers, lanes, scheduling, reconciliation – without the surface area of a production framework.

What's implemented

• Core API – createElement / JSX
• Hooks – useState
• Reconciler
  • Fiber tree, work loop – performUnitOfWork, beginWork, completeUnitOfWork
  • Lanes-based priority – markUpdateLaneFromFiberToRoot, childLanes bubbling
  • Fiber pooling – getOrCreateWorkInProgressFiber
  • Keyed reconciliation
• Renderer (host config) – createDom, updateDom, commitRootFiber
• Scheduler – MessageChannel-backed work loop (performWorkUntilDeadline, scheduleWorkUntilDeadline), 5ms time-slice budget

Some test coverage for reconciler, hooks, DOM output.

Planned

• Effects (useEffect)
• memo

Credit

Structurally based on pomber/didact