Why file system access matters in Node.js - Challenge Your Understanding

Challenge - 5 Problems

🧠 Conceptual

intermediate

Why is file system access important in Node.js?

Which of the following best explains why file system access is important in Node.js applications?

A It enables Node.js to create graphical user interfaces for desktop applications.

B It lets Node.js run code faster by compiling files into machine code automatically.

C It allows Node.js to read and write files, enabling data storage and retrieval on the server.

D It allows Node.js to connect directly to databases without any drivers.

💡 Hint

Think about what servers need to do with files like logs, configs, or user uploads.

Node.js uses file system access to read and write files on the server. This is essential for storing data, configuration, and handling uploads.

❓ component_behavior

intermediate

What happens when reading a file asynchronously?

Consider this Node.js code snippet using the fs.promises.readFile method:

import { promises as fs } from 'fs';

async function readData() {
  const data = await fs.readFile('data.txt', 'utf8');
  console.log(data);
}
readData();

What will this code do when run if data.txt exists and contains the text "Hello World"?

A It will throw a syntax error because <code>await</code> cannot be used outside a function.

B It will print "Hello World" to the console after reading the file asynchronously.

C It will print an empty string because the file is read asynchronously.

D It will crash because <code>fs.promises</code> does not exist.

💡 Hint

Look at how await is used inside an async function.

The code reads the file data.txt asynchronously and waits for the content before printing it. Since the file contains "Hello World", that text is printed.

🔧 Debug

advanced

Identify the error in this file write code

What error will this Node.js code produce?

import { writeFile } from 'fs';

writeFile('output.txt', 'Test data', (err) => {
  if (err) throw err;
  console.log('File saved!');
});

A No error; the file will be saved and 'File saved!' printed.

B ReferenceError because <code>writeFile</code> is not imported correctly from 'fs'.

C TypeError because the callback function is missing.

D SyntaxError due to missing semicolon after <code>writeFile</code> call.

💡 Hint

Check how writeFile is imported from the 'fs' module in Node.js.

No error; writeFile is correctly imported as a named export from fs for the callback-based API. The file will be written asynchronously, and 'File saved!' logged if successful.

📝 Syntax

advanced

Which option correctly reads a file synchronously?

Which of the following Node.js code snippets correctly reads a file synchronously and stores its content in content?

A

import fs from 'fs';
const content = fs.readFile('file.txt', 'utf8');

B

import { readFileSync } from 'fs/promises';
const content = await readFileSync('file.txt', 'utf8');

C

import { readFile } from 'fs';
const content = readFile('file.txt', 'utf8');

D

import { readFileSync } from 'fs';
const content = readFileSync('file.txt', 'utf8');

💡 Hint

Remember synchronous functions do not use callbacks or promises.

readFileSync is the synchronous method to read files in Node.js. It returns the file content directly. The other options either use async methods incorrectly or import from wrong modules.

❓ state_output

expert

What is the output of this asynchronous file read sequence?

Given this Node.js code, what will be printed to the console?

import { promises as fs } from 'fs';

async function readFiles() {
  const file1 = fs.readFile('file1.txt', 'utf8');
  const file2 = fs.readFile('file2.txt', 'utf8');
  const content1 = await file1;
  const content2 = await file2;
  console.log(content1.trim() + ' & ' + content2.trim());
}
readFiles();

Assume file1.txt contains "Hello" and file2.txt contains "World" with trailing newlines.

A "Hello & World"

B "Hello\n & World\n"

C An error because <code>await</code> is used incorrectly.

D "HelloWorld"

💡 Hint

Consider how await works with promises and what trim() does.

The code reads both files asynchronously, waits for their content, trims whitespace including newlines, then joins them with ' & '. The output is "Hello & World".