Why Node.js for server-side JavaScript in Node.js - Challenge Your Understanding

Challenge - 5 Problems

🧠 Conceptual

intermediate

Why is Node.js considered efficient for handling many simultaneous connections?

Node.js uses a special model to handle many users at once without slowing down. What is this model called?

A Synchronous blocking calls for each request

B Using multiple processes for each user

C Event-driven, non-blocking I/O

D Multi-threading with one thread per connection

💡 Hint

Think about how Node.js avoids waiting for tasks to finish before starting new ones.

Node.js uses an event-driven, non-blocking I/O model. This means it can start tasks and move on without waiting, allowing it to handle many connections efficiently.

❓ component_behavior

intermediate

What happens when a blocking operation is used in Node.js?

Consider a Node.js server that uses a blocking function to read a large file. What is the effect on the server's ability to handle other requests?

A The server creates a new thread to handle the blocking operation

B The server pauses and waits until the blocking operation finishes, delaying other requests

C The server continues handling other requests without delay

D The server crashes immediately

💡 Hint

Think about what blocking means: does it stop the whole server or just one part?

Blocking operations stop the single thread Node.js runs on, so the server cannot handle other requests until the operation finishes.

📝 Syntax

advanced

Identify the correct way to import a built-in Node.js module in ES modules syntax

Which option correctly imports the fs module using ES modules syntax in Node.js?

A import fs from 'fs';

B import { fs } from 'fs';

C const fs = require('fs');

D const fs = import('fs');

💡 Hint

ES modules use import keyword differently than CommonJS require.

In ES modules, you import the default export with import fs from 'fs';. The require syntax is for CommonJS modules.

🔧 Debug

advanced

Why does this Node.js code cause the server to freeze?

Look at this code snippet:

const http = require('http');

http.createServer((req, res) => {
  while(true) {}
  res.end('Hello');
}).listen(3000);

Why does the server freeze and not respond?

Node.js

const http = require('http');

http.createServer((req, res) => {
  while(true) {}
  res.end('Hello');
}).listen(3000);

A The server runs out of memory and crashes

B The server port 3000 is already in use

C The res.end() is called too early

D The infinite loop blocks the event loop, preventing response

💡 Hint

Think about what happens when code never finishes running inside the request handler.

The infinite loop blocks the single-threaded event loop, so the server cannot process any other events or send responses.

❓ state_output

expert

What is the output of this asynchronous Node.js code?

Consider this code snippet:

console.log('Start');
setTimeout(() => {
  console.log('Timeout');
}, 0);
console.log('End');

What is the order of the console output?

Node.js

console.log('Start');
setTimeout(() => {
  console.log('Timeout');
}, 0);
console.log('End');

A Start\nEnd\nTimeout

B Timeout\nStart\nEnd

C Start\nTimeout\nEnd

D End\nStart\nTimeout

💡 Hint

Remember that setTimeout callbacks run after the current code finishes.

Even with 0 delay, setTimeout runs after the current synchronous code, so 'Start' and 'End' print first, then 'Timeout'.