path.extname for file extensions in Node.js - Mini Project: Build & Apply

Using path.extname to Extract File Extensions in Node.js

📖 Scenario: You are building a simple Node.js script to help organize files by their extensions. To do this, you need to extract the file extension from each filename.

🎯 Goal: Create a Node.js script that uses path.extname to get the file extension from a list of filenames.

📋 What You'll Learn

Create an array called files with the exact filenames: 'report.pdf', 'photo.jpg', 'archive.zip', 'notes.txt'

Create a variable called extToFind and set it to '.jpg'

Use a for loop with the variable file to iterate over files and create an array extensions that stores the extension of each file using path.extname(file)

Add a final line that exports the extensions array using module.exports = extensions

💡 Why This Matters

🌍 Real World

Extracting file extensions is useful when organizing files, validating uploads, or processing files differently based on type.

💼 Career

Understanding how to use Node.js built-in modules like path and how to manipulate arrays is essential for backend JavaScript development.

1

Create the list of filenames

Create an array called files with these exact filenames: 'report.pdf', 'photo.jpg', 'archive.zip', 'notes.txt'

Node.js

// Your code here

Need a hint?

Use square brackets [] to create an array and separate items with commas.

2

Add a variable for the extension to find

Create a variable called extToFind and set it to the string '.jpg'

Node.js

const files = ['report.pdf', 'photo.jpg', 'archive.zip', 'notes.txt'];
// Your code here

Need a hint?

Use const to declare a variable and assign the string '.jpg'.

3

Extract extensions using path.extname in a loop

Use a for loop with the variable file to iterate over files. Inside the loop, use path.extname(file) to get the extension and store all extensions in an array called extensions.

Node.js

const files = ['report.pdf', 'photo.jpg', 'archive.zip', 'notes.txt'];
const extToFind = '.jpg';

// Your code here

Need a hint?

Remember to require('path') at the top. Use extensions.push(path.extname(file)) inside the loop.

4

Export the extensions array

Add a final line that exports the extensions array using module.exports = extensions

Node.js

const path = require('path');
const files = ['report.pdf', 'photo.jpg', 'archive.zip', 'notes.txt'];
const extToFind = '.jpg';

const extensions = [];
for (const file of files) {
    extensions.push(path.extname(file));
}

// Your code here

Need a hint?

Use module.exports = extensions to make the array available outside this file.