Vercel React Best Practices

JetBrainsOfficialCreated by VercelDistributed by JetBrains

Skill
Guidelines
Software development
MIT
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From the author

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.

— the description by Vercel

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

Vercel React Best Practices provides a structured set of 64 rules designed to guide developers in writing and refactoring React and Next.js code. The guidelines are organized into eight categories ranging from eliminating request waterfalls and optimizing bundle sizes to managing re-renders and server-side performance. Each rule is categorized by priority to help developers focus on high-impact improvements for their applications.

What it does

Provides 64 specific rules for React and Next.js optimization
Categorizes rules by priority and impact level
Offers guidance on eliminating request waterfalls
Includes patterns for bundle size and server-side performance
Details techniques for managing client-side data fetching and re-renders
Supplies reference material for advanced React patterns

When to use it

When writing new React components or Next.js pages
During the implementation of client or server-side data fetching
When reviewing code for performance patterns
When refactoring existing React or Next.js codebases
When aiming to reduce bundle size or improve load times

Advantages

Organized by priority to address critical issues first
Covers a wide range of performance-related topics
Maintained by Vercel for relevance to the Next.js ecosystem
Provides clear prefixes for identifying rule categories

Usage examples

“How can I improve my data fetching in a Next.js page to avoid waterfalls?”: The agent will reference rules like async-parallel and async-defer-await to suggest using Promise.all or deferring await statements.
“What is the best way to handle heavy components in my React app?”: The agent will suggest using bundle-dynamic-imports to implement next/dynamic for better bundle management.

Install

Download the skill as a ZIP:
https://mp-staging.autogineer.com/agent-skills/jetbrains/vercel-react-best-practices/download

Unzip it into the cross-client skills folder of your project:

mkdir -p .agents/skills && unzip vercel-react-best-practices.zip -d .agents/skills

Documentation by Vercel

Vercel React Best Practices

Comprehensive performance optimization guide for React and Next.js applications, maintained by Vercel. Contains 64 rules across 8 categories, 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

Rule Categories by Priority

Priority	Category	Impact	Prefix
1	Eliminating Waterfalls	CRITICAL	`async-`
2	Bundle Size Optimization	CRITICAL	`bundle-`
3	Server-Side Performance	HIGH	`server-`
4	Client-Side Data Fetching	MEDIUM-HIGH	`client-`
5	Re-render Optimization	MEDIUM	`rerender-`
6	Rendering Performance	MEDIUM	`rendering-`
7	JavaScript Performance	LOW-MEDIUM	`js-`
8	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 next/dynamic 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. Server-Side Performance (HIGH)

server-auth-actions - Authenticate server actions like API routes
server-cache-react - Use React.cache() for per-request deduplication
server-cache-lru - Use LRU cache for cross-request caching
server-dedup-props - Avoid duplicate serialization in RSC props
server-hoist-static-io - Hoist static I/O (fonts, logos) to module level
server-serialization - Minimize data passed to client components
server-parallel-fetching - Restructure components to parallelize fetches
server-after-nonblocking - Use after() for non-blocking operations

4. Client-Side Data Fetching (MEDIUM-HIGH)

client-swr-dedup - Use SWR for automatic request deduplication
client-event-listeners - Deduplicate global event listeners
client-passive-event-listeners - Use passive listeners for scroll
client-localstorage-schema - Version and minimize localStorage data

5. 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-split-combined-hooks - Split hooks with independent dependencies
rerender-move-effect-to-event - Put interaction logic in event handlers
rerender-transitions - Use startTransition for non-urgent updates
rerender-use-deferred-value - Defer expensive renders to keep input responsive
rerender-use-ref-transient-values - Use refs for transient frequent values
rerender-no-inline-components - Don't define components inside components

6. 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
rendering-resource-hints - Use React DOM resource hints for preloading
rendering-script-defer-async - Use defer or async on script tags

7. 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
js-flatmap-filter - Use flatMap to map and filter in one pass

8. 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

Files

AGENTS.md92.3 KiB
ATTRIBUTION.mdAdded by AutoGineer864 B
README.md3.3 KiB
SKILL.md6.7 KiB
metadata.json921 B
rules/_sections.md1.5 KiB
rules/_template.md631 B
rules/advanced-event-handler-refs.md1.4 KiB
rules/advanced-init-once.md958 B
rules/advanced-use-latest.md1.0 KiB
rules/async-api-routes.md1.1 KiB
rules/async-defer-await.md2.0 KiB
rules/async-dependencies.md1.3 KiB
rules/async-parallel.md654 B
rules/async-suspense-boundaries.md2.5 KiB
rules/bundle-barrel-imports.md2.3 KiB
rules/bundle-conditional.md949 B
rules/bundle-defer-third-party.md920 B
rules/bundle-dynamic-imports.md791 B
rules/bundle-preload.md1.1 KiB
rules/client-event-listeners.md1.9 KiB
rules/client-localstorage-schema.md1.9 KiB
rules/client-passive-event-listeners.md1.6 KiB
rules/client-swr-dedup.md1.1 KiB
rules/js-batch-dom-css.md3.2 KiB
rules/js-cache-function-results.md1.9 KiB
rules/js-cache-property-access.md532 B
rules/js-cache-storage.md1.6 KiB
rules/js-combine-iterations.md753 B
rules/js-early-exit.md1.1 KiB
rules/js-flatmap-filter.md1.4 KiB
rules/js-hoist-regexp.md1.0 KiB
rules/js-index-maps.md837 B
rules/js-length-check-first.md1.7 KiB
rules/js-min-max-loop.md2.2 KiB
rules/js-set-map-lookups.md532 B
rules/js-tosorted-immutable.md1.7 KiB
rules/rendering-activity.md564 B
rules/rendering-animate-svg-wrapper.md1.2 KiB
rules/rendering-conditional-render.md980 B
rules/rendering-content-visibility.md815 B
rules/rendering-hoist-jsx.md1.0 KiB
rules/rendering-hydration-no-flicker.md2.3 KiB
rules/rendering-hydration-suppress-warning.md872 B
rules/rendering-resource-hints.md2.5 KiB
rules/rendering-script-defer-async.md1.9 KiB
rules/rendering-svg-precision.md588 B
rules/rendering-usetransition-loading.md2.0 KiB
rules/rerender-defer-reads.md973 B
rules/rerender-dependencies.md824 B
rules/rerender-derived-state-no-effect.md1.2 KiB
rules/rerender-derived-state.md728 B
rules/rerender-functional-setstate.md2.9 KiB
rules/rerender-lazy-state-init.md2.0 KiB
rules/rerender-memo-with-default-value.md1.1 KiB
rules/rerender-memo.md1.1 KiB
rules/rerender-move-effect-to-event.md1.2 KiB
rules/rerender-no-inline-components.md2.1 KiB
rules/rerender-simple-expression-in-memo.md1018 B
rules/rerender-split-combined-hooks.md1.8 KiB
rules/rerender-transitions.md1.0 KiB
rules/rerender-use-deferred-value.md1.8 KiB
rules/rerender-use-ref-transient-values.md1.7 KiB
rules/server-after-nonblocking.md2.0 KiB
rules/server-auth-actions.md2.6 KiB
rules/server-cache-lru.md1.3 KiB
rules/server-cache-react.md2.2 KiB
rules/server-dedup-props.md2.0 KiB
rules/server-hoist-static-io.md4.3 KiB
rules/server-parallel-fetching.md1.5 KiB
rules/server-serialization.md996 B

rules/js-batch-dom-css.md

title: Avoid Layout Thrashing impact: MEDIUM impactDescription: prevents forced synchronous layouts and reduces performance bottlenecks tags: javascript, dom, css, performance, reflow, layout-thrashing

Avoid Layout Thrashing

Avoid interleaving style writes with layout reads. When you read a layout property (like offsetWidth, getBoundingClientRect(), or getComputedStyle()) between style changes, the browser is forced to trigger a synchronous reflow.

This is OK (browser batches style changes):

function updateElementStyles(element: HTMLElement) {
  // Each line invalidates style, but browser batches the recalculation
  element.style.width = '100px'
  element.style.height = '200px'
  element.style.backgroundColor = 'blue'
  element.style.border = '1px solid black'
}

Incorrect (interleaved reads and writes force reflows):

function layoutThrashing(element: HTMLElement) {
  element.style.width = '100px'
  const width = element.offsetWidth  // Forces reflow
  element.style.height = '200px'
  const height = element.offsetHeight  // Forces another reflow
}

Correct (batch writes, then read once):

function updateElementStyles(element: HTMLElement) {
  // Batch all writes together
  element.style.width = '100px'
  element.style.height = '200px'
  element.style.backgroundColor = 'blue'
  element.style.border = '1px solid black'
  
  // Read after all writes are done (single reflow)
  const { width, height } = element.getBoundingClientRect()
}

Correct (batch reads, then writes):

function avoidThrashing(element: HTMLElement) {
  // Read phase - all layout queries first
  const rect1 = element.getBoundingClientRect()
  const offsetWidth = element.offsetWidth
  const offsetHeight = element.offsetHeight
  
  // Write phase - all style changes after
  element.style.width = '100px'
  element.style.height = '200px'
}

Better: use CSS classes

.highlighted-box {
  width: 100px;
  height: 200px;
  background-color: blue;
  border: 1px solid black;
}

function updateElementStyles(element: HTMLElement) {
  element.classList.add('highlighted-box')
  
  const { width, height } = element.getBoundingClientRect()
}

React example:

// Incorrect: interleaving style changes with layout queries
function Box({ isHighlighted }: { isHighlighted: boolean }) {
  const ref = useRef<HTMLDivElement>(null)
  
  useEffect(() => {
    if (ref.current && isHighlighted) {
      ref.current.style.width = '100px'
      const width = ref.current.offsetWidth // Forces layout
      ref.current.style.height = '200px'
    }
  }, [isHighlighted])
  
  return <div ref={ref}>Content</div>
}

// Correct: toggle class
function Box({ isHighlighted }: { isHighlighted: boolean }) {
  return (
    <div className={isHighlighted ? 'highlighted-box' : ''}>
      Content
    </div>
  )
}

Prefer CSS classes over inline styles when possible. CSS files are cached by the browser, and classes provide better separation of concerns and are easier to maintain.

See this gist and CSS Triggers for more information on layout-forcing operations.

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Security

No issues found by our static scan· No issues found

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

Attribution and licence

Created by

Vercel

Publisher

JetBrains (Official)

Distributed by

JetBrains

Source

JetBrains/skills · react-best-practices · commit 3f53782

Licence

MIT License (redistribution allowed)

ATTRIBUTION.md (written by AutoGineer)

Synced

2026-11-08

AutoGineer is not affiliated with or endorsed by Vercel or JetBrains.

Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download vercel-react-best-practices.zip

From the author

AutoGineer summary

What it does

When to use it

Advantages

Usage examples

Install

Documentation by Vercel

Vercel React Best Practices

When to Apply

Rule Categories by Priority

Quick Reference

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)

How to Use

Full Compiled Document

Files

rules/js-batch-dom-css.md

title: Avoid Layout Thrashing impact: MEDIUM impactDescription: prevents forced synchronous layouts and reduces performance bottlenecks tags: javascript, dom, css, performance, reflow, layout-thrashing

Avoid Layout Thrashing

Requirements and compatibility

Security

Attribution and licence

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