Request object properties in Node.js - Mini Project: Build & Apply

Explore Request Object Properties in Node.js

📖 Scenario: You are building a simple Node.js server that listens to HTTP requests. You want to learn how to access different properties of the request object to understand what the client is sending.

🎯 Goal: Create a Node.js HTTP server that reads and logs specific properties from the request object: the HTTP method, the URL, and the headers.

📋 What You'll Learn

Create a basic HTTP server using Node.js http module

Access the method property of the request object

Access the url property of the request object

Access the headers property of the request object

💡 Why This Matters

🌍 Real World

Web servers need to read request properties to understand what the client wants and respond correctly.

💼 Career

Knowing how to access request properties is essential for backend developers working with Node.js to build APIs and web applications.

1

Set up a basic HTTP server

Create a Node.js HTTP server using http.createServer and assign it to a variable called server. The server should have a callback function with parameters req and res. Do not add any logic inside the callback yet.

Node.js

const http = require('http');

// Your code here

Hint

Use http.createServer with a function that takes req and res as parameters.

2

Add a port number variable

Create a constant variable called port and set it to 3000. This will be the port your server listens on.

Node.js

const http = require('http');

const server = http.createServer((req, res) => {
  // Request handling will be added later
});

// Your code here

Hint

Use const port = 3000; to define the port number.

3

Access and store request properties

Inside the server callback, create three constants: method assigned to req.method, url assigned to req.url, and headers assigned to req.headers.

Node.js

const http = require('http');

const server = http.createServer((req, res) => {
  // Your code here
});

const port = 3000;

Hint

Use const method = req.method; and similarly for url and headers.

4

Start the server listening on the port

Add a line to make the server listen on the port variable using server.listen(port).

Node.js

const http = require('http');

const server = http.createServer((req, res) => {
  const method = req.method;
  const url = req.url;
  const headers = req.headers;
});

const port = 3000;

// Your code here

Hint

Use server.listen(port); to start the server.

Practice

1. Which property of the Node.js request object contains the HTTP method used by the client, such as GET or POST?

easy

A. req.method

B. req.url

C. req.headers

D. req.body

Solution

1. Step 1: Understand the request object properties

   The request object has properties like method, url, headers, and body that describe the client's request.

2. Step 2: Identify the property for HTTP method

   The HTTP method (GET, POST, etc.) is stored in req.method.

3. Final Answer:

   req.method -> Option A

4. Quick Check:

   HTTP method = req.method [OK]

Hint: HTTP method is always in req.method [OK]

Common Mistakes:

• Confusing req.url with HTTP method
• Using req.body to get method
• Trying to find method in req.headers

2. Which of the following is the correct way to access the URL path from the request object in Node.js?

easy

A. req.route

B. req.path

C. req.url

D. req.address

Solution

1. Step 1: Recall the property for URL path

   The request object stores the full URL path in req.url.

2. Step 2: Verify other options

   req.path is not standard in Node.js core, req.route is used in some frameworks but not for URL path, and req.address is invalid.

3. Final Answer:

   req.url -> Option C

4. Quick Check:

   URL path = req.url [OK]

Hint: URL path is stored in req.url [OK]

Common Mistakes:

• Using req.path which is not standard in Node.js
• Confusing req.route with URL
• Trying to access req.address which doesn't exist

3. Consider the following Node.js code snippet:

const http = require('http');
const server = http.createServer((req, res) => {
  res.end(req.headers['content-type']);
});
server.listen(3000);

If a client sends a request with header Content-Type: application/json, what will be the output?

medium

A. application/json

B. content-type

C. undefined

D. Error

Solution

1. Step 1: Understand how headers are accessed

   Headers in Node.js request object are stored in lowercase keys inside req.headers. So content-type is the correct key.

2. Step 2: Check the code output

   The code returns req.headers['content-type'], which matches the header sent by the client: application/json.

3. Final Answer:

   application/json -> Option A

4. Quick Check:

   Header content-type value = application/json [OK]

Hint: Headers keys are lowercase in req.headers [OK]

Common Mistakes:

• Using 'Content-Type' instead of 'content-type' key
• Expecting req.headers to be case-sensitive
• Assuming undefined if header not found

4. What is wrong with this Node.js code snippet that tries to read JSON data from the request body?

const http = require('http');
const server = http.createServer((req, res) => {
  const data = req.body;
  res.end(data);
});
server.listen(3000);

medium

A. res.end cannot send data

B. req.body is undefined without parsing the data

C. req.body is a function, not a property

D. Missing require for http module

Solution

1. Step 1: Understand how request body works in Node.js

   In Node.js core, req.body is not automatically populated. You must collect data chunks and parse them manually or use middleware.

2. Step 2: Identify the error in the code

   The code tries to access req.body directly, which will be undefined, causing the response to send undefined.

3. Final Answer:

   req.body is undefined without parsing the data -> Option B

4. Quick Check:

   req.body needs manual parsing [OK]

Hint: req.body is empty unless parsed manually or with middleware [OK]

Common Mistakes:

• Assuming req.body is auto-filled in Node.js core
• Trying to send undefined data without error
• Confusing res.end usage

5. You want to log the client's IP address and the requested URL path in a Node.js HTTP server. Which code snippet correctly accesses these properties from the request object?

hard

A. console.log(req.connection.remoteAddress, req.path);

B. console.log(req.ip, req.path);

C. console.log(req.address, req.route);

D. console.log(req.socket.remoteAddress, req.url);

Solution

1. Step 1: Identify how to get client IP in Node.js

   The client IP is accessible via req.socket.remoteAddress or req.connection.remoteAddress. The req.socket is the modern standard.

2. Step 2: Identify how to get URL path

   The URL path is stored in req.url. Other options like req.path or req.route are not standard in Node.js core.

3. Step 3: Compare options

   console.log(req.socket.remoteAddress, req.url); uses req.socket.remoteAddress and req.url, which is correct and modern.

4. Final Answer:

   console.log(req.socket.remoteAddress, req.url); -> Option D

5. Quick Check:

   IP = req.socket.remoteAddress, URL = req.url [OK]

Hint: Use req.socket.remoteAddress and req.url for IP and path [OK]

Common Mistakes:

• Using req.ip which is Express-specific
• Using req.path which is not in Node.js core
• Trying to access req.address or req.route which don't exist