Routing requests manually in Node.js - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output when a GET request is made to '/'?

Consider this Node.js server code that manually routes requests. What will the server respond with when a GET request is made to the root path '/'?

Node.js

import http from 'http';

const server = http.createServer((req, res) => {
  if (req.method === 'GET' && req.url === '/') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Home Page');
  } else if (req.method === 'GET' && req.url === '/about') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('About Page');
  } else {
    res.writeHead(404, { 'Content-Type': 'text/plain' });
    res.end('Not Found');
  }
});

server.listen(3000);

A The server responds with 'Not Found' and status 404.

B The server responds with 'About Page' and status 200.

C The server responds with 'Home Page' and status 200.

D The server throws an error and crashes.

💡 Hint

Check the condition that matches the request method and URL.

The code checks if the request method is GET and the URL is '/'. If so, it responds with 'Home Page' and status 200. Other paths or methods get different responses.

📝 Syntax

intermediate

Which option causes a syntax error in manual routing?

Look at these code snippets for routing requests manually in Node.js. Which one will cause a syntax error?

A if (req.method === 'GET' && req.url === '/') { res.end('OK'); }

B if (req.method === 'GET' && req.url === '/about') { res.end('About'); }

C if (req.method === 'POST' && req.url === '/submit') { res.end('Submitted'); }

D if req.method === 'GET' && req.url === '/' { res.end('OK'); }

💡 Hint

Check the syntax of the if statement.

Option D is missing parentheses around the condition in the if statement, causing a syntax error.

🔧 Debug

advanced

Why does this manual routing code always respond with 'Not Found'?

This Node.js server code is supposed to respond with 'Hello' on GET '/' requests, but it always responds with 'Not Found'. What is the cause?

Node.js

import http from 'http';

const server = http.createServer((req, res) => {
  if (req.method = 'GET' && req.url === '/') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Hello');
  } else {
    res.writeHead(404, { 'Content-Type': 'text/plain' });
    res.end('Not Found');
  }
});

server.listen(3000);

A The single '=' assigns 'GET' to req.method, but the condition is always false, so 'Not Found' is sent.

B The single '=' assigns 'GET' to req.method, so the condition is always true and 'Hello' is sent.

C The code throws a runtime error because req.method is read-only.

D The server never starts because of a syntax error.

💡 Hint

Check the operator used in the if condition.

Using '=' assigns 'GET' to req.method, which is truthy, so the condition is always true and 'Hello' is sent. This is a bug because it should use '===' to compare.

❓ state_output

advanced

What is the response when a POST request is made to '/submit'?

Given this manual routing code, what will the server respond with when a POST request is made to '/submit'?

Node.js

import http from 'http';

const server = http.createServer((req, res) => {
  if (req.method === 'GET' && req.url === '/') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Home');
  } else if (req.method === 'POST' && req.url === '/submit') {
    res.writeHead(201, { 'Content-Type': 'text/plain' });
    res.end('Submitted');
  } else {
    res.writeHead(404, { 'Content-Type': 'text/plain' });
    res.end('Not Found');
  }
});

server.listen(3000);

A The server responds with 'Submitted' and status 201.

B The server responds with 'Home' and status 200.

C The server responds with 'Not Found' and status 404.

D The server throws an error because POST is not handled.

💡 Hint

Check the condition that matches POST requests to '/submit'.

The code explicitly checks for POST requests to '/submit' and responds with status 201 and 'Submitted'.

🧠 Conceptual

expert

What is a key limitation of manual routing in Node.js HTTP servers?

When manually routing requests in Node.js using the http module, what is a main limitation compared to using a routing framework?

A Manual routing requires writing repetitive code for each route, making it hard to scale and maintain.

B Manual routing automatically handles query parameters and middleware, which can cause unexpected behavior.

C Manual routing prevents the server from handling concurrent requests efficiently.

D Manual routing forces the use of synchronous code, blocking the event loop.

💡 Hint

Think about code complexity and maintenance.

Manual routing requires explicit if-else checks for each route, leading to repetitive and hard-to-maintain code as the app grows. Frameworks provide cleaner abstractions.