Routing is one of the most important concepts in Express.js. It defines how your application responds to client requests made to specific endpoints (URLs).

In this tutorial, you’ll learn:

• Introduction to Routing in Express.js
• HTTP Methods & Route Handling
• CRUD Operations in Express
• Route Parameters
• Query Parameters
• Template Routes

Introduction to Routing in Express.js

Routing refers to determining how an application responds to a client request to a specific endpoint.

Basic syntax:

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Welcome to Express Routing!');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

Here:

• app.get() → Handles GET request
• '/' → Route path
• (req, res) → Request & Response objects

HTTP Methods in Express

Express supports different HTTP methods:

MethodPurposeGET | Retrieve data
POST | Create data
PUT | Update data
DELETE | Delete data

Example:

app.post('/users', (req, res) => {
  res.send('User Created');
});

app.put('/users/:id', (req, res) => {
  res.send('User Updated');
});

app.delete('/users/:id', (req, res) => {
  res.send('User Deleted');
});

CRUD in Express.js

CRUD stands for:

• C → Create
• R → Read
• U → Update
• D → Delete

Example with dummy array:

let users = [];

// CREATE
app.post('/users', (req, res) => {
  users.push(req.body);
  res.send('User Added');
});

// READ
app.get('/users', (req, res) => {
  res.json(users);
});

// UPDATE
app.put('/users/:id', (req, res) => {
  users[req.params.id] = req.body;
  res.send('User Updated');
});

// DELETE
app.delete('/users/:id', (req, res) => {
  users.splice(req.params.id, 1);
  res.send('User Deleted');
});

Route Parameters in Express

Route parameters are used to capture values from the URL.

Example:

app.get('/users/:id', (req, res) => {
  res.send(`User ID is ${req.params.id}`);
});

If user visits:

http://localhost:3000/users/5

Output:

User ID is 5

👉 req.params is used to access route parameters.

Query Parameters in Express

Query parameters are optional values passed in the URL after ?.

Example URL:

http://localhost:3000/search?name=John&age=25

Code:

app.get('/search', (req, res) => {
  const name = req.query.name;
  const age = req.query.age;
  res.send(`Name: ${name}, Age: ${age}`);
});

👉 req.query is used to access query parameters.

Template Routes in Express

Template routes allow dynamic URL matching using parameters.

Example:

app.get('/products/:category/:id', (req, res) => {
  res.send(`Category: ${req.params.category}, Product ID: ${req.params.id}`);
});

URL:

/products/electronics/101

Output:

Category: electronics, Product ID: 101

Using Express Router (Modular Routing)

For larger applications, we use Router:

const express = require('express');
const router = express.Router();

router.get('/', (req, res) => {
  res.send('User Home');
});

module.exports = router;

Then in main file:

const userRoutes = require('./routes/users');
app.use('/users', userRoutes);