path.basename and path.dirname in Node.js - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of path.basename with extension

What is the output of the following Node.js code using path.basename?

Node.js

import path from 'path';
const filePath = '/home/user/docs/letter.txt';
console.log(path.basename(filePath, '.txt'));

A 'letter'

B '/home/user/docs/letter.txt'

C 'docs'

D 'letter.txt'

💡 Hint

The second argument to path.basename removes the file extension if it matches.

The path.basename function returns the last part of a path. When you provide a second argument, it removes that extension from the result if it matches. Here, '.txt' is removed from 'letter.txt', so the output is 'letter'.

❓ Predict Output

intermediate

Output of path.dirname with nested path

What does the following code print using path.dirname?

Node.js

import path from 'path';
const filePath = '/var/www/html/index.html';
console.log(path.dirname(filePath));

A '/var/www/html/index.html'

B 'html'

C '/var/www'

D '/var/www/html'

💡 Hint

path.dirname returns the directory part of the path, excluding the file name.

The path.dirname function returns everything before the last slash in the path. Here, it returns '/var/www/html' because 'index.html' is the file name.

❓ component_behavior

advanced

Behavior of path.basename with trailing slash

What is the output of this code snippet using path.basename on a path with a trailing slash?

Node.js

import path from 'path';
const dirPath = '/usr/local/bin/';
console.log(path.basename(dirPath));

A 'bin'

B 'local'

C '' (empty string)

D '/'

💡 Hint

path.basename returns an empty string when the path ends with a trailing slash.

The path.basename function returns the last portion of a path, ignoring trailing slashes. Here, '/usr/local/bin/' ends with a slash, but path.basename ignores it and returns 'bin'.

📝 Syntax

advanced

Identify the syntax error in path usage

Which option contains a syntax error when importing and using path.dirname in Node.js ES modules?

A import path from 'path'; console.log(path.dirname('/a/b/c.txt'));

B const path = require('path'); console.log(path.dirname('/a/b/c.txt'));

C import path from 'path'; console.log(path.dirname('/a/b/c.txt')

D import { dirname } from 'path'; console.log(dirname('/a/b/c.txt'));

💡 Hint

Check for missing parentheses or syntax mistakes in the code.

Option C is missing a closing parenthesis in the console.log call, causing a syntax error.

🔧 Debug

expert

Why does path.basename return an empty string?

Given the code below, why does path.basename return an empty string?

Node.js

import path from 'path';
const p = '/folder/subfolder/';
console.log(path.basename(p));

A Because the path is invalid and basename throws an error.

B Because the path ends with a slash, so basename returns empty string.

C Because basename always returns empty string for directories.

D Because the path is relative, basename returns empty string.

💡 Hint

Think about how trailing slashes affect basename output.

path.basename returns an empty string if the path ends with a slash (/), treating it as a directory path with no trailing filename. Here, '/folder/subfolder/' ends with a slash, so it returns an empty string.

Practice

1. What does path.basename return when given a full file path?

easy

A. The folder path only

B. The file name with extension

C. The full path unchanged

D. The file extension only

Solution

1. Step 1: Understand path.basename purpose

   This function extracts the last part of a path, which is usually the file name with its extension.

2. Step 2: Compare with other path parts

   Unlike path.dirname which returns the folder path, path.basename returns the file name part.

3. Final Answer:

   The file name with extension -> Option B

4. Quick Check:

   basename = file name [OK]

Hint: basename gives file name, dirname gives folder path [OK]

Common Mistakes:

• Confusing basename with dirname
• Expecting basename to return folder path
• Thinking basename returns file extension only

2. Which of the following is the correct syntax to get the directory name from a path using Node.js path module?

easy

A. path.getDirName('/home/user/file.txt')

B. path.getdirname('/home/user/file.txt')

C. path.dirName('/home/user/file.txt')

D. path.dirname('/home/user/file.txt')

Solution

1. Step 1: Recall correct method name in path module

   The correct method to get the directory name is dirname, all lowercase.

2. Step 2: Check method call syntax

   It is called as path.dirname(pathString), so path.dirname('/home/user/file.txt') matches exactly.

3. Final Answer:

   path.dirname('/home/user/file.txt') -> Option D

4. Quick Check:

   dirname method syntax = path.dirname('/home/user/file.txt') [OK]

Hint: Use exact method name dirname() with lowercase letters [OK]

Common Mistakes:

• Capitalizing method names incorrectly
• Using getDirName or similar incorrect names
• Misspelling dirname as dirName

3. What will be the output of the following code?

const path = require('path');
const fullPath = '/var/www/html/index.html';
console.log(path.basename(fullPath));
console.log(path.dirname(fullPath));

medium

A. index.html/var/www/html

B. /var/www/html/index.htmlindex.html

C. index/var/www/html/index.html

D. /var/www/htmlindex.html

Solution

1. Step 1: Evaluate path.basename(fullPath)

   This returns the file name with extension, which is index.html.

2. Step 2: Evaluate path.dirname(fullPath)

   This returns the folder path containing the file, which is /var/www/html.

3. Final Answer:

   index.html
   /var/www/html -> Option A

4. Quick Check:

   basename = file name, dirname = folder path [OK]

Hint: basename prints file, dirname prints folder path [OK]

Common Mistakes:

• Swapping basename and dirname outputs
• Expecting basename to return folder path
• Confusing output order

4. Identify the error in this code snippet:

const path = require('path');
const filePath = '/usr/local/bin/node';
console.log(path.baseName(filePath));
console.log(path.dirname(filePath));

medium

A. Incorrect method name 'baseName' should be 'basename'

B. Missing import of 'path' module

C. Wrong argument type passed to dirname

D. No error, code runs fine

Solution

1. Step 1: Check method names used

   The method path.baseName is incorrect because the correct method is all lowercase basename.

2. Step 2: Verify other parts

   The path module is imported correctly and dirname usage is correct, so no other errors.

3. Final Answer:

   Incorrect method name 'baseName' should be 'basename' -> Option A

4. Quick Check:

   Method names are case-sensitive [OK]

Hint: Check method name spelling and case carefully [OK]

Common Mistakes:

• Using wrong case in method names
• Assuming method names are case-insensitive
• Ignoring error messages about undefined functions

5. Given the path /home/user/docs/letter.txt, how can you use path.basename and path.dirname together to print:
Folder: /home/user/docs
File: letter.txt
Which code snippet achieves this?

hard

A. console.log(`Folder: ${path.dirname(path.basename(filePath))}`);
console.log(`File: ${path.basename(path.dirname(filePath))}`);

B. console.log(`Folder: ${path.basename(filePath)}`);
console.log(`File: ${path.dirname(filePath)}`);

C. console.log(`Folder: ${path.dirname(filePath)}`);
console.log(`File: ${path.basename(filePath)}`);

D. console.log(`Folder: ${filePath.dirname()}`);
console.log(`File: ${filePath.basename()}`);

Solution

1. Step 1: Use path.dirname to get folder path

   Calling path.dirname(filePath) returns the folder path /home/user/docs.

2. Step 2: Use path.basename to get file name

   Calling path.basename(filePath) returns the file name letter.txt.

3. Step 3: Combine in template strings for output

   Using template literals with these calls prints the desired output lines.

4. Final Answer:

   console.log(`Folder: ${path.dirname(filePath)}`); console.log(`File: ${path.basename(filePath)}`); -> Option C

5. Quick Check:

   dirname = folder, basename = file [OK]

Hint: dirname for folder, basename for file name [OK]

Common Mistakes:

• Swapping basename and dirname calls
• Trying to call basename/dirname on strings directly
• Using incorrect method chaining