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
33 lines
753 B
Markdown
33 lines
753 B
Markdown
---
|
|
title: Combine Multiple Array Iterations
|
|
impact: LOW-MEDIUM
|
|
impactDescription: reduces iterations
|
|
tags: javascript, arrays, loops, performance
|
|
---
|
|
|
|
## Combine Multiple Array Iterations
|
|
|
|
Multiple `.filter()` or `.map()` calls iterate the array multiple times. Combine into one loop.
|
|
|
|
**Incorrect (3 iterations):**
|
|
|
|
```typescript
|
|
const admins = users.filter(u => u.isAdmin)
|
|
const testers = users.filter(u => u.isTester)
|
|
const inactive = users.filter(u => !u.isActive)
|
|
```
|
|
|
|
**Correct (1 iteration):**
|
|
|
|
```typescript
|
|
const admins: User[] = []
|
|
const testers: User[] = []
|
|
const inactive: User[] = []
|
|
|
|
for (const user of users) {
|
|
if (user.isAdmin) admins.push(user)
|
|
if (user.isTester) testers.push(user)
|
|
if (!user.isActive) inactive.push(user)
|
|
}
|
|
```
|