# React Best Practices

> >-

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

## Install

```sh
agentstack add skill-michelve-hugin-cowork-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

Comprehensive performance optimization guide for React applications (Vite SPA), adapted from Vercel Engineering. Contains rules across 7 categories, prioritized by impact to guide automated refactoring and code generation.

**Note:** Server-side (RSC/Next.js) rules have been removed - this project uses Vite + Express, not Next.js.

## When to Apply

Reference these guidelines when:

- Writing new React components
- Implementing data fetching (client-side with TanStack Query)
- Reviewing code for performance issues
- Refactoring existing React code
- Optimizing bundle size or load times

## Rule Categories by Priority

| Priority | Category                  | Impact      | Prefix       |
| -------- | ------------------------- | ----------- | ------------ |
| 1        | Eliminating Waterfalls    | CRITICAL    | `async-`     |
| 2        | Bundle Size Optimization  | CRITICAL    | `bundle-`    |
| 3        | Client-Side Data Fetching | MEDIUM-HIGH | `client-`    |
| 4        | Re-render Optimization    | MEDIUM      | `rerender-`  |
| 5        | Rendering Performance     | MEDIUM      | `rendering-` |
| 6        | JavaScript Performance    | LOW-MEDIUM  | `js-`        |
| 7        | Advanced Patterns         | LOW         | `advanced-`  |

## Quick Reference

### 1. Eliminating Waterfalls (CRITICAL)

- `async-defer-await` - Move await into branches where actually used
- `async-parallel` - Use Promise.all() for independent operations
- `async-dependencies` - Use better-all for partial dependencies
- `async-api-routes` - Start promises early, await late in API routes
- `async-suspense-boundaries` - Use Suspense to stream content

### 2. Bundle Size Optimization (CRITICAL)

- `bundle-barrel-imports` - Import directly, avoid barrel files
- `bundle-dynamic-imports` - Use React.lazy() for heavy components
- `bundle-defer-third-party` - Load analytics/logging after hydration
- `bundle-conditional` - Load modules only when feature is activated
- `bundle-preload` - Preload on hover/focus for perceived speed

### 3. Client-Side Data Fetching (MEDIUM-HIGH)

- `client-tanstack-query` - Use TanStack Query for automatic deduplication and caching
- `client-event-listeners` - Deduplicate global event listeners
- `client-passive-event-listeners` - Use passive listeners for scroll
- `client-localstorage-schema` - Version and minimize localStorage data

### 4. Re-render Optimization (MEDIUM)

- `rerender-defer-reads` - Don't subscribe to state only used in callbacks
- `rerender-memo` - Extract expensive work into memoized components
- `rerender-memo-with-default-value` - Hoist default non-primitive props
- `rerender-dependencies` - Use primitive dependencies in effects
- `rerender-derived-state` - Subscribe to derived booleans, not raw values
- `rerender-derived-state-no-effect` - Derive state during render, not effects
- `rerender-functional-setstate` - Use functional setState for stable callbacks
- `rerender-lazy-state-init` - Pass function to useState for expensive values
- `rerender-simple-expression-in-memo` - Avoid memo for simple primitives
- `rerender-move-effect-to-event` - Put interaction logic in event handlers
- `rerender-transitions` - Use startTransition for non-urgent updates
- `rerender-use-ref-transient-values` - Use refs for transient frequent values

### 5. Rendering Performance (MEDIUM)

- `rendering-animate-svg-wrapper` - Animate div wrapper, not SVG element
- `rendering-content-visibility` - Use content-visibility for long lists
- `rendering-hoist-jsx` - Extract static JSX outside components
- `rendering-svg-precision` - Reduce SVG coordinate precision
- `rendering-hydration-no-flicker` - Use inline script for client-only data
- `rendering-hydration-suppress-warning` - Suppress expected mismatches
- `rendering-activity` - Use Activity component for show/hide
- `rendering-conditional-render` - Use ternary, not && for conditionals
- `rendering-usetransition-loading` - Prefer useTransition for loading state

### 6. JavaScript Performance (LOW-MEDIUM)

- `js-batch-dom-css` - Group CSS changes via classes or cssText
- `js-index-maps` - Build Map for repeated lookups
- `js-cache-property-access` - Cache object properties in loops
- `js-cache-function-results` - Cache function results in module-level Map
- `js-cache-storage` - Cache localStorage/sessionStorage reads
- `js-combine-iterations` - Combine multiple filter/map into one loop
- `js-length-check-first` - Check array length before expensive comparison
- `js-early-exit` - Return early from functions
- `js-hoist-regexp` - Hoist RegExp creation outside loops
- `js-min-max-loop` - Use loop for min/max instead of sort
- `js-set-map-lookups` - Use Set/Map for O(1) lookups
- `js-tosorted-immutable` - Use toSorted() for immutability

### 7. Advanced Patterns (LOW)

- `advanced-event-handler-refs` - Store event handlers in refs
- `advanced-init-once` - Initialize app once per app load
- `advanced-use-latest` - useLatest for stable callback refs

## How to Use

Read individual rule files for detailed explanations and code examples:

```
rules/async-parallel.md
rules/bundle-barrel-imports.md
```

Each rule file contains:

- Brief explanation of why it matters
- Incorrect code example with explanation
- Correct code example with explanation
- Additional context and references

## Full Compiled Document

For the complete guide with all rules expanded: `AGENTS.md`

For the full reference document: `references/react-best-practices-reference.md`

## Source & license

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

- **Author:** [michelve](https://github.com/michelve)
- **Source:** [michelve/hugin-cowork](https://github.com/michelve/hugin-cowork)
- **License:** MIT

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-michelve-hugin-cowork-react-best-practices
- Seller: https://agentstack.voostack.com/s/michelve
- Browse the marketplace: https://agentstack.voostack.com/browse

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