Claude-skill-registry js-set-map-lookups
Use Set and Map for O(1) membership lookups instead of array.includes(). Apply when checking membership repeatedly or performing frequent lookups against a collection.
install
source · Clone the upstream repo
git clone https://github.com/majiayu000/claude-skill-registry
Claude Code · Install into ~/.claude/skills/
T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/data/js-set-map-lookups" ~/.claude/skills/majiayu000-claude-skill-registry-js-set-map-lookups && rm -rf "$T"
manifest:
skills/data/js-set-map-lookups/SKILL.mdsource content
Use Set/Map for O(1) Lookups
Convert arrays to Set/Map for repeated membership checks.
Incorrect (O(n) per check):
const allowedIds = ['a', 'b', 'c', ...] items.filter(item => allowedIds.includes(item.id))
Correct (O(1) per check):
const allowedIds = new Set(['a', 'b', 'c', ...]) items.filter(item => allowedIds.has(item.id))