Express.js Basics Routing

Routing in Express.js refers to the way that requests are handled and directed to specific routes based on the URL and HTTP method. Express provides a simple and flexible routing mechanism to define various endpoints for your application. In this guide, you will learn how to work with basic routes and HTTP methods.

 

Key Features of Routing in Express.js

• Route Definition: Routes are defined using HTTP methods like GET, POST, PUT, DELETE, etc.
• Dynamic Routes: You can create dynamic routes with parameters to handle variable parts in URLs.
• Middleware Support: Routes can use middleware for request processing, validation, and more.

 

Steps to Define Basic Routes in Express.js

Set up a Basic Express Application
If you haven't already, initialize a Node.js project and install Express:

npm init -y
npm install express --save

Create a Basic Express Application
Create an app.js file and define a few routes:

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

// Define a simple route for the home page
app.get('/', (req, res) => {
    res.send('Hello, Express!');
});

// Define a route for the "about" page
app.get('/about', (req, res) => {
    res.send('This is the About page');
});

// Define a route with a dynamic parameter
app.get('/user/:id', (req, res) => {
    const userId = req.params.id;
    res.send(`User ID: ${userId}`);
});

// Define a POST route for form submission
app.post('/submit', (req, res) => {
    res.send('Form Submitted!');
});

// Start the server
app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

Run the Application
To start the server, run the following command in your terminal:

node app.js

Test the Routes
Open your browser or use tools like Postman to test the following routes:

• http://localhost:3000/ – Displays "Hello, Express!"
• http://localhost:3000/about – Displays "This is the About page"
• http://localhost:3000/user/123 – Displays "User ID: 123" (dynamic route)
• Use Postman or another tool to send a POST request to http://localhost:3000/submit to see "Form Submitted!" as the response.

Route Handling for Multiple Methods
Express allows you to define different routes for various HTTP methods. For example:

app.route('/product')
    .get((req, res) => {
        res.send('GET request to /product');
    })
    .post((req, res) => {
        res.send('POST request to /product');
    })
    .put((req, res) => {
        res.send('PUT request to /product');
    });

Using Query Parameters
You can access query parameters using req.query:

app.get('/search', (req, res) => {
    const searchTerm = req.query.q;
    res.send(`Search results for: ${searchTerm}`);
});

For a request like http://localhost:3000/search?q=express, the response will be: Search results for: express.

 

Summary

Express.js routing is a powerful feature that allows you to define how your application responds to different HTTP methods (GET, POST, PUT, DELETE) and routes. You can easily create static, dynamic, and parameterized routes. Express's routing capabilities also support query parameters, middleware, and multiple HTTP methods for a single route.