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React

Updated 2 min read index source
On this page7
  1. Mental model
  2. Rendering internals
  3. Hooks
  4. Performance
  5. Server rendering and data
  6. Patterns
  7. Known gaps

React

Baseline: React 19.2 with React Compiler 1.0 assumed. See Stack baseline — 2026-2027.

The compiler changes advice, not just versions. Auto-memoization means most manual useMemo/useCallback guidance is now wrong for new code. Files below still carrying the old advice are flagged; the rewrite is phase 7 in Modernization plan — 2026-2027 interview prep.

Mental model

File Covers
React: the component model what React is, JSX, the component model
React Elements vs Components elements are descriptions, components are functions
React State vs Props the two inputs, and who owns each
Prop Children composition via children
React Fragment grouping without a wrapper node
Key Property in React list identity, and why index keys corrupt state

Rendering internals

File Covers
Virtual DOM in React what the VDOM is and isn’t
Shadow DOM vs Virtual DOM unrelated concepts with confusable names
React Fiber the fiber architecture
React Reconciliation diffing, bailouts, when subtrees remount
Concurrent Rendering — useTransition, useDeferredValue, How Priorities Work interruptible rendering, transitions
React Lifecycle mount/update/unmount, effects as the modern equivalent
Synthetic Events in React the event delegation layer
React Portal rendering outside the parent DOM node

Hooks

File Covers
Useful Hooks in React the built-in set
useEffect Deep — Cleanup, StrictMode Double-Invoke, Dep-Array Bugs, Effect Events dependencies, cleanup, and when you don’t need an effect
useRef Hook in React mutable boxes and DOM handles
Stale Closures and the Rules of Hooks the classic hook bug and the rules that prevent it
Controlled vs Uncontrolled Components form state ownership

Performance

File Covers
React Compiler the compiler — read this before the memo files
React.memo manual memoization: mechanism, and when the compiler bails out
React Pure Components purity and bailout conditions
Context Performance Traps why context re-renders everything, and the splitting fix

Server rendering and data

File Covers
Server Components (RSC) — What Runs Where, Serialization, the "use client" Boundary RSC — what runs where
Hydration — Selective, Progressive, Mismatches attaching to server HTML, and mismatch errors
Suspense for Data — vs Suspense for Code, Error Boundaries, Streaming SSR Suspense as a data-loading boundary
React 19 — Actions, useActionState, useOptimistic, use(), ref as Prop what landed in 19

Patterns

File Covers
Higher-Order Components (HOC) higher-order components (largely superseded by hooks)
MVC Pattern in React how React relates to MVC

Known gaps

A 9,850-line vendored copy of a third-party interview-questions repo previously sat at this path. It carried sponsor banners, was largely class-component-era React, and duplicated the files above. It was removed in phase 2; recover it from git history if needed.

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