path.basename and path.dirname in Node.js - Mini Project: Build & Apply

Using path.basename and path.dirname in Node.js

📖 Scenario: You are working on a Node.js script that processes file paths. You want to extract the file name and the directory name from a given file path.

🎯 Goal: Build a simple Node.js script that uses path.basename to get the file name and path.dirname to get the directory name from a file path string.

📋 What You'll Learn

Import the built-in path module

Create a variable with a specific file path string

Use path.basename to get the file name

Use path.dirname to get the directory name

💡 Why This Matters

🌍 Real World

File path manipulation is common in scripts that organize, move, or analyze files on your computer or server.

💼 Career

Understanding how to extract parts of file paths is useful for backend developers, DevOps engineers, and anyone working with file systems in Node.js.

1

Import the path module and create a file path variable

Write code to import the built-in path module using require('path'). Then create a variable called filePath and set it to the string "/home/user/docs/letter.txt".

Node.js

# Import the path module and create filePath variable
# Your code here

Hint

Use const path = require('path') to import the module. Then assign the exact string "/home/user/docs/letter.txt" to filePath.

2

Create variables for base name and directory name

Create two variables: baseName and dirName. Set baseName to the result of path.basename(filePath). Set dirName to the result of path.dirname(filePath).

Node.js

const path = require('path');
const filePath = "/home/user/docs/letter.txt";
# Create baseName and dirName variables using path.basename and path.dirname
# Your code here

Hint

Use path.basename(filePath) to get the file name and path.dirname(filePath) to get the directory path.

3

Add a variable for file extension

Create a variable called extName and set it to the result of path.extname(filePath) to get the file extension.

Node.js

const path = require('path');
const filePath = "/home/user/docs/letter.txt";
const baseName = path.basename(filePath);
const dirName = path.dirname(filePath);
# Create extName variable using path.extname
# Your code here

Hint

Use path.extname(filePath) to get the file extension like '.txt'.

4

Export the variables as a module

Add a module.exports statement to export an object with baseName, dirName, and extName properties.

Node.js

const path = require('path');
const filePath = "/home/user/docs/letter.txt";
const baseName = path.basename(filePath);
const dirName = path.dirname(filePath);
const extName = path.extname(filePath);
# Export baseName, dirName, and extName
# Your code here

Hint

Use module.exports = { baseName, dirName, extName } to export the variables.

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