d9bcdc4a8d
Skills included: - pr-reviewer: Adapted for Gitea/GitHub via platform-aware scripts (dropped fetch_pr_data.py and add_inline_comment.py, kept generate_review_files.py) - code-review-excellence: Methodology and checklists (React, TS, Python, etc.) - vercel-react-best-practices: 57 rules for React/Next.js performance - tailwind-design-system: Tailwind CSS v4 patterns, CVA, design tokens New shell scripts added to ~/.claude/scripts/git/: - pr-diff.sh: Get PR diff (GitHub gh / Gitea API) - pr-metadata.sh: Get PR metadata as normalized JSON Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
30 lines
728 B
Markdown
30 lines
728 B
Markdown
---
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title: Subscribe to Derived State
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impact: MEDIUM
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impactDescription: reduces re-render frequency
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tags: rerender, derived-state, media-query, optimization
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---
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## Subscribe to Derived State
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Subscribe to derived boolean state instead of continuous values to reduce re-render frequency.
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**Incorrect (re-renders on every pixel change):**
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```tsx
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function Sidebar() {
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const width = useWindowWidth() // updates continuously
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const isMobile = width < 768
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return <nav className={isMobile ? 'mobile' : 'desktop'} />
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}
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```
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**Correct (re-renders only when boolean changes):**
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```tsx
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function Sidebar() {
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const isMobile = useMediaQuery('(max-width: 767px)')
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return <nav className={isMobile ? 'mobile' : 'desktop'} />
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}
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```
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