Files
cal-diy-oidc/.claude/skills/vercel-react-best-practices/rules/rerender-memo.md
T
Udit Takkar 7a9fdd5a0c feat: add react best practises and web design skills (#26918)
## What does this PR do?

This PR adds https://vercel.com/blog/introducing-react-best-practices for your coding agent using `npx add-skill vercel-labs/agent-skills` command

The skills are added to `.claude/`, `.cursor/`, and `.opencode/` directories to provide React and Next.js performance optimization guidance for AI-assisted workflows.

## Updates since last revision

Addressed Cubic AI review feedback for issues with confidence >= 9/10:

- **rerender-dependencies.md** - Replaced `console.log(user.id)` with `fetchUserDetails(user.id)` to avoid logging sensitive information
- **server-after-nonblocking.md** - Removed `sessionCookie` from `logUserAction` call to avoid logging sensitive authentication data, added `await` to async call
- **bundle-conditional.md** - Added `loadError` state and `setLoadError` setter to fix undefined `setEnabled` reference
- **advanced-event-handler-refs.md** - Updated `useWindowEvent` handler signature to accept `Event` parameter and forward it to the stored handler
- **rerender-derived-state.md** - Closed `<nav>` elements in both examples for valid JSX

Fixes applied to both `.claude` and `.cursor` skill directories for consistency.

## Mandatory Tasks (DO NOT REMOVE)

- [x] I have self-reviewed the code (A decent size PR without self-review might be rejected).
- [x] N/A I have updated the developer docs in /docs if this PR makes changes that would require a [documentation change](https://cal.com/docs). If N/A, write N/A here and check the checkbox.
- [x] N/A, I confirm automated tests are in place that prove my fix is effective or that my feature works.

## How should this be tested?

These are documentation files for AI coding agents. No runtime testing required - review the markdown files to verify the example code snippets are correct.

## Checklist for human review

- [ ] Verify example code snippets in the skill files are syntactically correct
- [ ] Confirm the fixes don't introduce new issues in the documentation examples
- [ ] Check that `.claude` and `.cursor` directories have consistent content

---

Link to Devin run: https://app.devin.ai/sessions/f7f7e67fdeea4b22a4817d63ed9e1759
Requested by: unknown ()
2026-01-16 17:19:34 +05:30

1.1 KiB

title, impact, impactDescription, tags
title impact impactDescription tags
Extract to Memoized Components MEDIUM enables early returns rerender, memo, useMemo, optimization

Extract to Memoized Components

Extract expensive work into memoized components to enable early returns before computation.

Incorrect (computes avatar even when loading):

function Profile({ user, loading }: Props) {
  const avatar = useMemo(() => {
    const id = computeAvatarId(user)
    return <Avatar id={id} />
  }, [user])

  if (loading) return <Skeleton />
  return <div>{avatar}</div>
}

Correct (skips computation when loading):

const UserAvatar = memo(function UserAvatar({ user }: { user: User }) {
  const id = useMemo(() => computeAvatarId(user), [user])
  return <Avatar id={id} />
})

function Profile({ user, loading }: Props) {
  if (loading) return <Skeleton />
  return (
    <div>
      <UserAvatar user={user} />
    </div>
  )
}

Note: If your project has React Compiler enabled, manual memoization with memo() and useMemo() is not necessary. The compiler automatically optimizes re-renders.