Adding Route Handlers to a Vanilla TypeScript HTTP Server

Use this skill whenever you need to add a new route to a TypeScript project that uses Node's built-in http module and a switch/case pathname router without Express or Next.js.

---

Step 0 — Confirm the routing style

Before writing any code, inspect server/index.ts (or whichever file starts the HTTP server). Look for:

http.createServer((req, res) => {
  const { pathname } = new URL(req.url!, `http://${req.headers.host}`);
  switch (pathname) {
    case '/api/foo': ...
  }
});

If you see this pattern, follow the steps below.
Do NOT use express.Router, next/server, or any framework-specific handler signature — even if other files in server/routes/ happen to use those patterns.

---

Step 1 — Create the route file

Create server/routes/<feature>.ts.
Use only the native Node types: http.IncomingMessage and http.ServerResponse.

// server/routes/health.ts
import http from 'http';

export async function handleHealth(
  req: http.IncomingMessage,
  res: http.ServerResponse
): Promise<void> {
  // Parse body for POST/PUT if needed
  const body = await readBody(req);   // helper shown in Step 3

  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({ status: 'ok' }));
}

Rules for the route file:

• Export the handler as a named async function (handle<Feature>).
• Accept exactly (req: http.IncomingMessage, res: http.ServerResponse).
• Return Promise<void>.
• Do not call next() or return a Response object.
• Handle errors internally and write an appropriate HTTP status + JSON body.

---

Step 2 — Import the handler in server/index.ts

Add a named import at the top of the file alongside any existing imports:

import { handleHealth } from './routes/health';

---

Step 3 — Add a case entry to the switch block

Locate the existing switch (pathname) block and add a new case:

switch (pathname) {
  case '/api/health':
    await handleHealth(req, res);
    break;

  // … existing cases …

  default:
    res.writeHead(404, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify({ error: 'Not found' }));
}

• Match the exact pathname string used by the client.
• Always break (or return) after calling the handler.
• Keep the default case last.

---

Step 4 — Optional: shared body-reading helper

If multiple routes need to parse a JSON request body, add a small utility rather than duplicating the logic:

// server/utils/readBody.ts
import http from 'http';

export function readBody(req: http.IncomingMessage): Promise<unknown> {
  return new Promise((resolve, reject) => {
    let data = '';
    req.on('data', (chunk) => (data += chunk));
    req.on('end', () => {
      try {
        resolve(data ? JSON.parse(data) : {});
      } catch {
        reject(new Error('Invalid JSON'));
      }
    });
    req.on('error', reject);
  });
}

Import and use it inside any route handler that needs it.

---

Checklist

• server/routes/<feature>.ts exists and exports a named async handler.
• Handler signature is (req: http.IncomingMessage, res: http.ServerResponse): Promise<void>.
• Handler always calls res.writeHead(...) and res.end(...) on every code path.
• Handler is imported in server/index.ts.
• A matching case entry is present in the switch (pathname) block.
• No Express / Next.js / Koa types or patterns were introduced.

---

Anti-patterns to avoid

❌ Wrong	✅ Correct
import { Router } from 'express'	import http from 'http'
export default function handler(req: NextApiRequest, ...)	export async function handleFoo(req: http.IncomingMessage, ...)
router.get('/foo', ...)	case '/api/foo': await handleFoo(req, res); break;
Returning a value from the handler	Calling res.end(...) and returning void