Node.js path.extname() Method

Last Updated : 4 Aug, 2026

The path.extname() method in Node.js is used to retrieve the extension of a file from a given path. It helps developers identify file formats and perform extension-based operations when working with files and directories.

  • Commonly used to validate or filter files based on their type.
  • Useful when handling uploads, file processing, or generating file-specific logic.
  • It helps in file validation, filtering, and path handling tasks.

Syntax:

path.extname(path)

where,

  • path: The file path from which the extension needs to be extracted.

Return Value: Returns an empty string if the specified path does not contain a file extension.

Example 1:

javascript 
// Node.js program to demonstrate the   
// path.extname() method

// Import the path module
const path = require('path');
 
path1 = path.extname("hello.txt");
console.log(path1)
 
path2 = path.extname("readme.md");
console.log(path2)
 
// File with no extension
// Returns empty string
path3 = path.extname("fileDump")
console.log(path3)
 
// File with blank extension
// Return only the period
path4 = path.extname("example.")
console.log(path4)
 
path5 = path.extname("readme.md.txt")
console.log(path5)
 
// Extension name of the current script
path6 = path.extname(__filename)
console.log(path6)

Output:

.txt
.md

.
.txt
.js

Example 2:

javascript 
// Node.js program to demonstrate the   
// path.extname() method

// Import the path module
const path = require('path');
 
// Comparing extensions from a
// list of file paths
paths_array = [
    "/home/user/website/index.html",
    "/home/user/website/style.css",
    "/home/user/website/bootstrap.css",
    "/home/user/website/main.js",
    "/home/user/website/contact_us.html",
    "/home/user/website/services.html",
]
 
paths_array.forEach(filePath => {
    if (path.extname(filePath) == ".html")
        console.log(filePath);
});

Output:

/home/user/website/index.html
/home/user/website/contact_us.html
/home/user/website/services.html

Use Cases of path.extname() Method

Use Cases of path.extname() Method

  • File Type Validation: Check whether a file has an allowed extension before processing or uploading it.
  • File Filtering: Display or process only specific file types, such as .jpg, .png, or .pdf.
  • Conditional File Handling: Apply different operations based on the file extension, such as opening images, documents, or videos with different logic.
Comment

Explore