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>
46 lines
1.0 KiB
Markdown
46 lines
1.0 KiB
Markdown
---
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title: Hoist RegExp Creation
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impact: LOW-MEDIUM
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impactDescription: avoids recreation
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tags: javascript, regexp, optimization, memoization
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---
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## Hoist RegExp Creation
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Don't create RegExp inside render. Hoist to module scope or memoize with `useMemo()`.
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**Incorrect (new RegExp every render):**
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```tsx
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function Highlighter({ text, query }: Props) {
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const regex = new RegExp(`(${query})`, 'gi')
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const parts = text.split(regex)
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return <>{parts.map((part, i) => ...)}</>
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}
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```
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**Correct (memoize or hoist):**
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```tsx
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const EMAIL_REGEX = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
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function Highlighter({ text, query }: Props) {
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const regex = useMemo(
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() => new RegExp(`(${escapeRegex(query)})`, 'gi'),
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[query]
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)
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const parts = text.split(regex)
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return <>{parts.map((part, i) => ...)}</>
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}
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```
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**Warning (global regex has mutable state):**
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Global regex (`/g`) has mutable `lastIndex` state:
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```typescript
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const regex = /foo/g
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regex.test('foo') // true, lastIndex = 3
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regex.test('foo') // false, lastIndex = 0
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```
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