Guide Book

A reference you can read front to back or dip into. Every chapter explains the syntax, and most topics have a 🔍 Behind the scenes section you can open to see what Python is actually doing, the details classes usually skip. Look for 🧭 Scenario cards for real-world uses, and press Try it on any example, then open the Inspect tab to look inside.

1. Chapter 1How React rendersElements, the render tree, reconciliation and commit — what actually happens between your function returning JSX and pixels changing.
2. Chapter 2JSXWhat JSX compiles to, the rules that trip people up, expressions versus statements, and how children and fragments work.
3. Chapter 3Components & propsProps as a one-way contract, defaults and destructuring, composition patterns, and why purity is a requirement rather than a style.
4. Chapter 4State & the render cycleWhy state is a snapshot, how updates are batched and queued, updater functions, and where state should live.
5. Chapter 5EffectsWhat `useEffect` is for, the dependency array, cleanup, and the many cases where the right answer is no effect at all.
6. Chapter 6The rules of hooksWhy hooks must be called unconditionally, what React stores between renders, the built-in set, and how to write your own.
7. Chapter 7Lists, keys & identityWhy keys exist, what a bad key actually breaks, and the rendering patterns for collections.
8. Chapter 8Context & sharing stateProp drilling, what context actually solves, the re-render cost nobody mentions, and when to reach for something else.
9. Chapter 9Refs & escaping ReactA mutable box that survives renders without causing them — for DOM nodes, timers, previous values and anything React should not manage.
10. Chapter 10Forms & eventsControlled and uncontrolled inputs, the synthetic event system, handler patterns, and why `onChange` fires on every keystroke.
11. Chapter 11PerformanceWhat actually costs time, `memo`, `useMemo` and `useCallback` and when they help, plus the structural fixes that beat all of them.