Request object properties in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the HTTP method from the request object.

Node.js

const method = req.[1];

Drag options to blanks, or click blank then click option'

Amethod

Burl

Cbody

Dheaders

Attempts:

3 left

💡 Hint

Common Mistakes

Using req.url instead of req.method

Trying to access req.body for the method

Using req.headers which holds headers, not method

The method property of the request object holds the HTTP method (GET, POST, etc.) used by the client.

2fill in blank

medium

Complete the code to get the URL path from the request object.

Node.js

const path = req.[1];

Drag options to blanks, or click blank then click option'

Amethod

Bpath

Curl

Dquery

Attempts:

3 left

💡 Hint

Common Mistakes

Using req.path which may not exist in plain Node.js

Using req.method which is the HTTP method

Using req.query which holds parsed query parameters

The url property contains the full URL path and query string sent by the client.

3fill in blank

hard

Fix the error in accessing the request headers property.

Node.js

const headers = req.[1];

Drag options to blanks, or click blank then click option'

Aheader

Bheaders

Chead

DheaderList

Attempts:

3 left

💡 Hint

Common Mistakes

Using singular 'header' instead of 'headers'

Trying to access 'head' or 'headerList' which do not exist

The correct property name is headers, which holds all HTTP headers as an object.

4fill in blank

hard

Fill both blanks to extract the query string parameters from the request URL.

Node.js

const url = require('url');
const queryObject = url.[1](req.[2], true).query;

Drag options to blanks, or click blank then click option'

Aparse

Burl

Cmethod

Dheaders

Attempts:

3 left

💡 Hint

Common Mistakes

Using req.method instead of req.url

Using url.method or url.headers which do not exist

Use url.parse to parse the request URL string and get the query parameters object.

5fill in blank

hard

Fill all three blanks to read JSON data sent in the request body using streams.

Node.js

let body = '';
req.on('[1]', chunk => {
  body += chunk.toString();
});
req.on('[2]', () => {
  const data = JSON.[3](body);
  console.log(data);
});

Drag options to blanks, or click blank then click option'

Adata

Bend

Cparse

Dstringify

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'end' event to collect chunks instead of 'data'

Using JSON.stringify instead of JSON.parse

Mixing event names or JSON methods

Listen for the 'data' event to collect chunks, 'end' event to finish, then parse the JSON string.

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