AgentSkillsCN

js_set_map_lookups

从Vercel导入技能：js_set_map_lookups

SKILL.md
--- frontmatter
description: Imported skill js_set_map_lookups from vercel
name: js_set_map_lookups
signature: a7fd781a6ba9ad49065961b6f9a90ef486bf6b648390e1a08704025f98e1642b
source: /a0/tmp/skills_research/vercel/skills/react-best-practices/rules/js-set-map-lookups.md

title: Use Set/Map for O(1) Lookups impact: LOW-MEDIUM impactDescription: O(n) to O(1) tags: javascript, set, map, data-structures, performance

Use Set/Map for O(1) Lookups

Convert arrays to Set/Map for repeated membership checks.

Incorrect (O(n) per check):

typescript
const allowedIds = ['a', 'b', 'c', ...]
items.filter(item => allowedIds.includes(item.id))

Correct (O(1) per check):

typescript
const allowedIds = new Set(['a', 'b', 'c', ...])
items.filter(item => allowedIds.has(item.id))