Core Code
Core Code Modern Dev Handbook
REACT Contents
React Fundamentals
React Architecture Overview JSX and Rendering Model Component Design Principles Props and Data Flow State Management with useState Side Effects with useEffect Event Handling Patterns Conditional Rendering Strategies Lists, Keys, and Reconciliation Forms and Controlled Components Component Composition Lifting State and Shared State Basic Routing with React Router Failure Modes in Beginner React Apps
React + TypeScript
Typing Functional Components Typing Props and Children useState and Type Inference useReducer with Type Safety Typing Event Handlers Generic Components Utility Types in React Discriminated Unions for UI State Strict Mode and Null Safety API Response Typing Strategies Form Typing Patterns Avoiding any and Unsafe Casts Type-Safe Context API Failure Modes in React + TypeScript
React Advanced Patterns
Custom Hooks Architecture Context vs Prop Drilling Tradeoffs Compound Components Pattern Controlled vs Uncontrolled Abstractions Render Props and Pattern Alternatives State Machines in React Performance Optimization Playbook Memoization Strategies Code Splitting and Lazy Loading Error Boundaries and Recovery Portal Architecture Large Scale Folder Structure Testing Strategy: Unit and Integration Common React Anti Patterns
React Production
CSR vs SSR vs SSG Hydration and Mismatch Failures Next.js Architecture Overview App Router Deep Dive Authentication Patterns Token Storage Security Role Based UI Control API Integration Patterns Rate Limiting and UI Resilience Frontend Security Checklist XSS in Modern React Observability in Frontend Bundle Optimization Production Incident Playbook
Distributed Systems
Distributed System Fundamentals CAP Theorem in Practice Consistency Models Replication Strategies Leader Election Concepts Consensus Algorithms Overview Event Driven Architectures Message Queues and Delivery Guarantees Idempotency Patterns Saga Pattern Circuit Breakers Backpressure and Flow Control Observability in Distributed Systems Failure Scenarios and Postmortems

Memoization Strategies

Memoization reduces rerenders only when referential stability is required. Learn correct use of React.memo, useMemo, and useCallback, and detect misuse that increases complexity without measurable gain.
On this page

Memoization Is a Tool, Not a Default

  • Memoization prevents rerenders caused by reference changes.
  • It does not fix state scoping problems.
  • Use only when profiling shows measurable benefit.

React.memo

  • Prevents rerender when props are shallow equal.
  • Useful for leaf components in large lists.
  • Do not wrap everything blindly.

useMemo

  • Caches expensive computation results.
  • Dependency array must be accurate.
  • Do not memoize cheap calculations.

useCallback

  • Stabilizes function identity.
  • Important when passing callbacks to memoized children.
  • Dependency correctness is critical.

Example: Correct Boundary

const Row = React.memo(function Row({ item }: { item: { id: string; name: string } }) {
  return <div>{item.name}</div>;
});

function List({ items }: { items: { id: string; name: string }[] }) {
  return (
    <>
      {items.map((item) => (
        <Row key={item.id} item={item} />
      ))}
    </>
  );
}

Common Misuse

  • Memoizing everything increases mental overhead.
  • Incorrect dependency arrays cause stale closures.
  • Memo around unstable objects provides no benefit.

Operational Checklist

  • Profiling proves rerender cost is meaningful.
  • State placement is already correct.
  • Dependency arrays are minimal and correct.
  • Memo boundaries are placed near expensive subtrees.
Code Splitting and Lazy Loading →