Edge Functions

Edge Functions allow you to run server-side code closer to your users than ever before. Unlike traditional serverless functions that run in a single region (like Finland-1), Edge Functions are deployed globally and execute in the region closest to the request.

Example

Here is a simple Edge Function that returns a personalized greeting based on the user's location.

// api/hello.ts
import type { NextRequest } from 'next/server';

export const config = {
  runtime: 'edge',
};

export default function handler(req: NextRequest) {
  const { searchParams } = new URL(req.url);
  const name = searchParams.get('name') || 'World';
  const country = req.geo?.country || 'the internet';

  return new Response(
    JSON.stringify({
      message: `Hello ${name} from ${country}!`,
      timestamp: Date.now(),
    }),
    {
      status: 200,
      headers: {
        'content-type': 'application/json',
      },
    }
  );
}

Runtime Environment

Nept Edge Functions run on the V8 engine, similar to Cloudflare Workers or Vercel Edge. This means:

• Fast Startup: No cold starts typical of Node.js containers.
• Web Standards: Uses standard Web APIs like Request, Response, fetch, and Streams.
• Limitations: Native Node.js APIs (like fs, child_process) are not available. You must use polyfills or alternative strategies.

Use Cases

• Authentication & Authorization: Verify JWTs at the edge before the request hits your origin.
• A/B Testing: Bucket users into different variants using cookies without client-side flicker.
• Geolocation Routing: Redirect users to localized content based on their IP address.
• Custom Headers: Add security headers or CORS policies dynamically.

Performance Limits

| Metric | Limit | | :--- | :--- | | Execution Time (Wall Clock) | 30s | | CPU Time | 50ms (Soft limit) | | Memory | 128 MB | | Deployment Size | 1 MB (Compressed) |