Nicholai
75168f7678
structure: state/CURRENT.md — 2-4 line session state (rewritten each session) events/ — json event bus (pull-based, optional context) persistent/ — important decisions (one doc per decision) emit — helper script for emitting events
25 lines
532 B
Markdown
25 lines
532 B
Markdown
---
|
|
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))
|
|
```
|