Request object properties in Node.js - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of accessing req.method in an Express.js route?

Consider this Express.js route handler:

app.get('/test', (req, res) => { res.send(req.method); });

What will be the output when a client sends a GET request to '/test'?

Node.js

app.get('/test', (req, res) => { res.send(req.method); });

A "POST"

B "GET"

C "/test"

D undefined

💡 Hint

The req.method property holds the HTTP method used for the request.

The req.method property in Express.js contains the HTTP method of the incoming request, such as GET, POST, PUT, etc. Since the route is accessed with a GET request, req.method will be "GET".

📝 Syntax

intermediate

Which option correctly accesses the query parameter 'id' from the request object in Express.js?

You want to get the value of the query parameter 'id' from the URL '/user?id=123'. Which code correctly accesses it inside a route handler?

Node.js

app.get('/user', (req, res) => { /* access id here */ });

A const id = req.params.id;

B const id = req.body.id;

C const id = req.query.id;

D const id = req.headers.id;

💡 Hint

Query parameters are part of the URL after the '?' symbol.

Query parameters are accessed via req.query in Express.js. req.params is for route parameters, req.body is for POST data, and req.headers is for HTTP headers.

🔧 Debug

advanced

What error occurs when accessing req.body without body-parser middleware?

Given this Express.js code:

app.post('/submit', (req, res) => { res.send(req.body.name); });

What happens if the client sends JSON data but the app does not use any body parsing middleware?

Node.js

app.post('/submit', (req, res) => { res.send(req.body.name); });

A ReferenceError: req is not defined

B SyntaxError: Unexpected token in JSON

C res.send sends the correct name value

D TypeError: Cannot read property 'name' of undefined

💡 Hint

Without middleware, req.body is not automatically parsed.

Without body-parser or equivalent middleware, req.body is undefined. Trying to access req.body.name causes a TypeError because you cannot read properties of undefined.

🧠 Conceptual

advanced

Which property of the request object contains the full URL path including query string?

In Express.js, which property of the request object gives the full URL path with query parameters included?

A req.originalUrl

B req.path

C req.url

D req.baseUrl

💡 Hint

One property preserves the original request URL including the query string.

req.originalUrl contains the full URL path and query string as requested by the client. req.url may be modified by middleware. req.path excludes query string. req.baseUrl is the matched route base.

❓ state_output

expert

What is the value of req.headers['content-type'] after a JSON POST request?

A client sends a POST request with JSON data and header 'Content-Type: application/json'. Inside the Express.js route, what is the value of req.headers['content-type']?

Node.js

app.post('/data', (req, res) => { res.send(req.headers['content-type']); });

A "application/json"

B "Application/JSON"

C undefined

D "application-json"

💡 Hint

HTTP headers are case-insensitive but stored in lowercase in Node.js.

Node.js converts all header names to lowercase. The value of 'content-type' header sent as 'application/json' remains exactly that string.