res.set for response headers in Express - Mini Project: Build & Apply

Setting Response Headers with res.set in Express

📖 Scenario: You are building a simple Express server that sends back a greeting message. To make your response more informative and secure, you want to add custom HTTP headers.

🎯 Goal: Learn how to use res.set in Express to add custom response headers before sending the response.

📋 What You'll Learn

Create an Express app with a single GET route at '/'

Use res.set to add a custom header 'X-Custom-Header' with value 'HelloHeader'

Add another header 'Content-Type' with value 'text/plain'

Send a plain text response 'Welcome to the header demo!'

💡 Why This Matters

🌍 Real World

Web servers often need to send custom headers for security, caching, or metadata. Using <code>res.set</code> in Express helps control these headers easily.

💼 Career

Backend developers use Express to build APIs and web servers. Knowing how to set response headers is essential for controlling client-server communication.

1

Create the Express app and basic route

Create a variable called express that requires the 'express' module. Then create a variable called app by calling express(). Finally, add a GET route at path '/' with a callback function that takes req and res as parameters.

Express

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

// Your code here

Need a hint?

Use require('express') to import Express and express() to create the app. Use app.get to define the route.

2

Add custom headers using res.set

Inside the GET route callback, use res.set to add a header 'X-Custom-Header' with value 'HelloHeader'. Also add a header 'Content-Type' with value 'text/plain'.

Express

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

app.get('/', (req, res) => {
  // Use res.set to add headers here
});

Need a hint?

Call res.set twice with the exact header names and values.

3

Send the plain text response

After setting the headers, use res.send to send the text 'Welcome to the header demo!' as the response body.

Express

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

app.get('/', (req, res) => {
  res.set('X-Custom-Header', 'HelloHeader');
  res.set('Content-Type', 'text/plain');
  // Send response here
});

Need a hint?

Use res.send with the exact string to send the response.

4

Start the Express server

Add a line to start the server by calling app.listen on port 3000 with a callback function that logs 'Server running on port 3000'.

Express

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

app.get('/', (req, res) => {
  res.set('X-Custom-Header', 'HelloHeader');
  res.set('Content-Type', 'text/plain');
  res.send('Welcome to the header demo!');
});

// Start the server here

Need a hint?

Use app.listen with port 3000 and a callback that logs the message.