Structuring Routes with express.Router()

Structuring Routes with express.Router()

As your API grows, keeping all routes in a single file becomes unmanageable. express.Router() creates a mini-application that has its own middleware and routing, and is then mounted onto the main app at a path prefix.

// src/routes/users.ts
import { Router } from "express";

const router = Router();

router.get("/", (req, res) => {
  res.json({ message: "list users" });
});

router.post("/", (req, res) => {
  res.status(201).json({ message: "create user" });
});

router.get("/:id", (req, res) => {
  res.json({ id: req.params.id });
});

export default router;

// src/app.ts
import express from "express";
import usersRouter from "./routes/users";

const app = express();
app.use(express.json());
app.use("/users", usersRouter);

export default app;

Recommended Project Structure

• src/app.ts — create and configure the Express app
• src/index.ts — call app.listen()
• src/routes/ — one file per resource router
• src/controllers/ — handler functions imported by routers
• src/middleware/ — shared middleware (auth, validation, logging)
• src/lib/ or src/services/ — business logic and DB access