JL Kruger
5422131782
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837 B
837 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.