bbb2f41591
- Created `openspec-ff-change` skill for fast-forward artifact creation. - Introduced `openspec-new-change` skill for structured change creation. - Developed `openspec-onboard` skill for guided onboarding through OpenSpec workflow. - Added `openspec-sync-specs` skill for syncing delta specs to main specs. - Implemented `openspec-verify-change` skill for verifying implementation against change artifacts. - Updated `.gitignore` to exclude OpenSpec generated files. - Added `skills-lock.json` to manage skill dependencies.
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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