Express.js — Node.js Framework

mkdir my-express-app
cd my-express-app
npm init -y
npm install express

const express = require("express");
const app = express();
const PORT = process.env.PORT || 3000;

app.get("/", (req, res) => {
  res.send("Hello from Express!");
});

app.listen(PORT, () => {
  console.log("Server চালু http://localhost:" + PORT);
});

// GET route
app.get("/users", (req, res) => {
  res.json([{ id: 1, name: "রহিম" }]);
});

// POST route
app.post("/users", (req, res) => {
  res.status(201).json({ message: "Created" });
});

// Route parameters
app.get("/users/:id", (req, res) => {
  res.json({ id: req.params.id });
});

// Router ব্যবহার
const router = express.Router();
router.get("/", (req, res) => res.json({ message: "List" }));
router.get("/:id", (req, res) => res.json({ id: req.params.id }));
app.use("/api/users", router);

// Built-in middleware
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

// Custom middleware
app.use((req, res, next) => {
  console.log(req.method, req.url, Date.now());
  next();
});

// Static files
app.use(express.static("public"));

// 404 handler
app.use((req, res) => {
  res.status(404).json({ error: "Not Found" });
});

// Error handler middleware
app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).json({ error: "Internal Server Error" });
});