React internals: Fiber, concurrent rendering, StrictMode, and why effects run twice in development
Fiber is React's internal architecture for scheduling and prioritizing work, and StrictMode helps surface unsafe patterns in development.
- Fiber enables more flexible rendering work
- Concurrent rendering changes scheduling, not your component API directly
- StrictMode may intentionally double-invoke some logic in dev
React internals: Fiber, concurrent rendering, StrictMode, and why effects run twice in development