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963 markdown files reformatted with the repository's pinned prettier so pnpm format:check covers the folded tree like every other repo file. The formatter's embedded-language pass also normalized code fences (TS semicolons, closed HTML tags in examples, lowercased CSS hex colors, one renumbered list that skipped an index). Alphanumeric token deltas vs the fold commit were audited file-by-file; all are formatter-equivalent markup normalizations plus the four sanitized skills.
850 B
850 B
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Build Index Maps for Repeated Lookups | LOW-MEDIUM | 1M ops to 2K ops | javascript, map, indexing, optimization, performance |
Build Index Maps for Repeated Lookups
Multiple .find() calls by the same key should use a Map.
Incorrect (O(n) per lookup):
function processOrders(orders: Order[], users: User[]) {
return orders.map((order) => ({
...order,
user: users.find((u) => u.id === order.userId),
}));
}
Correct (O(1) per lookup):
function processOrders(orders: Order[], users: User[]) {
const userById = new Map(users.map((u) => [u.id, u]));
return orders.map((order) => ({
...order,
user: userById.get(order.userId),
}));
}
Build map once (O(n)), then all lookups are O(1). For 1000 orders × 1000 users: 1M ops → 2K ops.