My-Weekly-ToDo-List/.opencode/skills/react-best-practices/rules/js-set-map-lookups.md
mARTin d92a8c7210 feat: add task actions (notes/delete) and refine animation logic
- Added 'onDelete' and 'onNotes' support to TaskItem.
- Implemented hover actions (Delete and Notes icons) for tasks.
- Added Notes Modal for editing task markdown content.
- Simplified navigation animation to remove blank flash (single-phase slide-in).
- Fixed syntax error in updateTask function.
- Updated styles for modal and task actions.
2026-02-01 12:25:53 +01:00

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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))
```