# React Best Practices

> React and Next.js performance optimization guidelines from Vercel Engineering. This skill should be used when writing, reviewing, or refactoring React/Next.js code to ensure optimal performance patterns. Triggers on tasks involving React components, Next.js pages, data fetching, bundle optimization, or performance improvements.

- **Type:** Skill
- **Install:** `agentstack add skill-koolamusic-claudefiles-react-best-practices`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [koolamusic](https://agentstack.voostack.com/s/koolamusic)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [koolamusic](https://github.com/koolamusic)
- **Source:** https://github.com/koolamusic/claudefiles/tree/main/skills/react-best-practices
- **Website:** https://andrewmiracle.com/claudefiles

## Install

```sh
agentstack add skill-koolamusic-claudefiles-react-best-practices
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# React Best Practices

## Overview

Comprehensive performance optimization guide for React and Next.js applications, containing 40+ rules across 8 categories. Rules are prioritized by impact to guide automated refactoring and code generation.

## When to Apply

Reference these guidelines when:
- Writing new React components or Next.js pages
- Implementing data fetching (client or server-side)
- Reviewing code for performance issues
- Refactoring existing React/Next.js code
- Optimizing bundle size or load times

## Priority-Ordered Guidelines

Rules are prioritized by impact:

| Priority | Category | Impact |
|----------|----------|--------|
| 1 | Eliminating Waterfalls | CRITICAL |
| 2 | Bundle Size Optimization | CRITICAL |
| 3 | Server-Side Performance | HIGH |
| 4 | Client-Side Data Fetching | MEDIUM-HIGH |
| 5 | Re-render Optimization | MEDIUM |
| 6 | Rendering Performance | MEDIUM |
| 7 | JavaScript Performance | LOW-MEDIUM |
| 8 | Advanced Patterns | LOW |

## Quick Reference

### Critical Patterns (Apply First)

**Eliminate Waterfalls:**
- Defer await until needed (move into branches)
- Use `Promise.all()` for independent async operations
- Start promises early, await late
- Use `better-all` for partial dependencies
- Use Suspense boundaries to stream content

**Reduce Bundle Size:**
- Avoid barrel file imports (import directly from source)
- Use `next/dynamic` for heavy components
- Defer non-critical third-party libraries
- Preload based on user intent

### High-Impact Server Patterns

- Use `React.cache()` for per-request deduplication
- Use LRU cache for cross-request caching
- Minimize serialization at RSC boundaries
- Parallelize data fetching with component composition

### Medium-Impact Client Patterns

- Use SWR for automatic request deduplication
- Defer state reads to usage point
- Use lazy state initialization for expensive values
- Use derived state subscriptions
- Apply `startTransition` for non-urgent updates

### Rendering Patterns

- Animate SVG wrappers, not SVG elements directly
- Use `content-visibility: auto` for long lists
- Prevent hydration mismatch with inline scripts
- Use explicit conditional rendering (`? :` not `&&`)

### JavaScript Patterns

- Batch DOM CSS changes via classes
- Build index maps for repeated lookups
- Cache repeated function calls
- Use `toSorted()` instead of `sort()` for immutability
- Early length check for array comparisons

## References

Full documentation with code examples is available in:

- `references/react-performance-guidelines.md` - Complete guide with all patterns
- `references/rules/` - Individual rule files organized by category

To look up a specific pattern, grep the rules directory:
```
grep -l "suspense" references/rules/
grep -l "barrel" references/rules/
grep -l "swr" references/rules/
```

## Rule Categories in `references/rules/`

- `async-*` - Waterfall elimination patterns
- `bundle-*` - Bundle size optimization
- `server-*` - Server-side performance
- `client-*` - Client-side data fetching
- `rerender-*` - Re-render optimization
- `rendering-*` - DOM rendering performance
- `js-*` - JavaScript micro-optimizations
- `advanced-*` - Advanced patterns

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [koolamusic](https://github.com/koolamusic)
- **Source:** [koolamusic/claudefiles](https://github.com/koolamusic/claudefiles)
- **License:** MIT
- **Homepage:** https://andrewmiracle.com/claudefiles

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-koolamusic-claudefiles-react-best-practices
- Seller: https://agentstack.voostack.com/s/koolamusic
- Browse the marketplace: https://agentstack.voostack.com/browse

---
Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.