3ac66feba2
gitignore 의 *.md / .claude/ 차단을 풀어 다음 파일을 git 으로 추적. - /CLAUDE.md, /AGENTS.md (루트 에이전트 가이드) - .agents/**/*.md (skills 문서 95개) - .claude/settings.json (Claude Code 프로젝트 설정) .claude/worktrees/ 는 git worktree 메타이므로 신규 ignore 라인으로 제외. Co-Authored-By: Claude Opus 4.7 (1M context) <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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