c86c93582e
- Add 8 new skills (62 total, up from 58) - Official Anthropic skills: docx, pdf, pptx, xlsx, brand-guidelines, internal-comms - Vercel Labs skills: react-best-practices, web-design-guidelines - Implement dual-versioning: -official/-anthropic and -community suffixes - Update README with new skill registry and credits - Regenerate skills_index.json (62 skills validated) - Add comprehensive walkthrough.md BREAKING CHANGE: Document skills (docx/pdf/pptx/xlsx) renamed with version suffixes
30 lines
724 B
Markdown
30 lines
724 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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