Node.js + Express — Build Your First API in 10 Minutes

Setting Up Express

npm init -y
npm install express

// server.js
const express = require('express');
const app = express();
const PORT = process.env.PORT || 3000;

app.use(express.json());

app.get('/', (req, res) => {
  res.json({ message: 'Welcome to the API' });
});

app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

Route Parameters and Query Strings

// GET /api/users/:id
app.get('/api/users/:id', (req, res) => {
  const { id } = req.params;
  res.json({ id, name: 'Alice' });
});

// GET /api/users?page=1&limit=10
app.get('/api/users', (req, res) => {
  const { page = 1, limit = 10 } = req.query;
  res.json({ page: Number(page), limit: Number(limit) });
});

Middleware

// Request logging middleware
app.use((req, res, next) => {
  console.log(`${req.method} ${req.url} - ${new Date().toISOString()}`);
  next();
});

// CORS middleware
const cors = require('cors');
app.use(cors());

Error Handling

// 404 handler
app.use((req, res) => {
  res.status(404).json({ error: 'Route not found' });
});

// Global error handler
app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(err.status || 500).json({ error: err.message });
});