A (Mostly) Complete Guide to React Rendering Behavior
by Mark Erikson · isquaredsoftware.com
Redux maintainer Mark Erikson explains when and why React re-renders: render versus commit phases, reconciliation and keys, update batching, React.memo, useMemo and useCallback, context propagation, and what actually causes performance problems.
More resources on React
Advanced React: Deep Dives, Investigations, Performance Patterns and Techniques
The senior-level tier the free material does not cover: it treats React as a system with failure modes rather than an API to memorise. Sixteen chapters on React's runtime behaviour: element diffing and reconciliation, the real causes of re-renders, the limits of memoization, refs and closures inside hooks, portals and error handling. Each chapter is an investigation with interactive examples, not an API walkthrough.
React TypeScript Cheatsheets
Community-maintained reference for typing React with TypeScript: props and children, hooks including useReducer and useRef, generic and polymorphic components, context, forms and events, error boundaries, plus migration notes for React 18 and 19 type changes. Production React is written in TypeScript, and react.dev deliberately teaches in JavaScript, leaving a real gap. This is the one place the ecosystem's typing conventions are collected and kept current across breaking @types/react changes.
Build Your Own React
Rodrigo Pombo rebuilds React from zero in eight incremental steps: createElement, the render function, concurrent scheduling, the fiber tree, commit phase, reconciliation, function components and a working useState. Roughly 200 lines of code, with a live diff at every step. Converts React from a set of memorised rules into a mechanism you have implemented. Explains why hooks must be called unconditionally, why keys matter, and what the fiber work loop actually does - knowledge the docs deliberately abstract away.
React Key Concepts, 2nd Edition
Reference-style book covering React 19: components, props, state, hooks, context, refs, form actions, the use() hook and server components, with practice exercises and a build project closing each chapter.
Redux Essentials Tutorial
The official eight-part Redux tutorial written by its maintainer, teaching Redux Toolkit slices, async thunks, data normalization and RTK Query for server-state caching, the modern answer for React apps that outgrow local component state. Covers the state-management and data-fetching half of the topic note, which react.dev intentionally leaves to the ecosystem.
Learn React — Official Documentation
The official React documentation's tutorial track, covering components, JSX, props, state, hooks, effects and escape hatches, with interactive in-browser sandboxes on nearly every page. Rewritten from scratch around function components and hooks. Nothing else in the topic should compete with it for the beginner slot.