dcaaef1011
Format: YYYY-MM-DD-description.md - 2026-01-19-infrastructure-deployment.md - 2026-01-19-backend-api-implementation.md (in progress) Co-Authored-By: Claude Sonnet 4.5 (1M context) <noreply@anthropic.com>
74 lines
2.0 KiB
Markdown
74 lines
2.0 KiB
Markdown
---
|
|
title: Use after() for Non-Blocking Operations
|
|
impact: MEDIUM
|
|
impactDescription: faster response times
|
|
tags: server, async, logging, analytics, side-effects
|
|
---
|
|
|
|
## Use after() for Non-Blocking Operations
|
|
|
|
Use Next.js's `after()` to schedule work that should execute after a response is sent. This prevents logging, analytics, and other side effects from blocking the response.
|
|
|
|
**Incorrect (blocks response):**
|
|
|
|
```tsx
|
|
import { logUserAction } from '@/app/utils'
|
|
|
|
export async function POST(request: Request) {
|
|
// Perform mutation
|
|
await updateDatabase(request)
|
|
|
|
// Logging blocks the response
|
|
const userAgent = request.headers.get('user-agent') || 'unknown'
|
|
await logUserAction({ userAgent })
|
|
|
|
return new Response(JSON.stringify({ status: 'success' }), {
|
|
status: 200,
|
|
headers: { 'Content-Type': 'application/json' }
|
|
})
|
|
}
|
|
```
|
|
|
|
**Correct (non-blocking):**
|
|
|
|
```tsx
|
|
import { after } from 'next/server'
|
|
import { headers, cookies } from 'next/headers'
|
|
import { logUserAction } from '@/app/utils'
|
|
|
|
export async function POST(request: Request) {
|
|
// Perform mutation
|
|
await updateDatabase(request)
|
|
|
|
// Log after response is sent
|
|
after(async () => {
|
|
const userAgent = (await headers()).get('user-agent') || 'unknown'
|
|
const sessionCookie = (await cookies()).get('session-id')?.value || 'anonymous'
|
|
|
|
logUserAction({ sessionCookie, userAgent })
|
|
})
|
|
|
|
return new Response(JSON.stringify({ status: 'success' }), {
|
|
status: 200,
|
|
headers: { 'Content-Type': 'application/json' }
|
|
})
|
|
}
|
|
```
|
|
|
|
The response is sent immediately while logging happens in the background.
|
|
|
|
**Common use cases:**
|
|
|
|
- Analytics tracking
|
|
- Audit logging
|
|
- Sending notifications
|
|
- Cache invalidation
|
|
- Cleanup tasks
|
|
|
|
**Important notes:**
|
|
|
|
- `after()` runs even if the response fails or redirects
|
|
- Works in Server Actions, Route Handlers, and Server Components
|
|
|
|
Reference: [https://nextjs.org/docs/app/api-reference/functions/after](https://nextjs.org/docs/app/api-reference/functions/after)
|