Node.js fs.readdir() Method

The fs.readdir() method is used to asynchronously read the contents of a given directory. The callback of this method returns an array of all the file names in the directory. The options argument can be used to change the format in which the files are returned from the method.

Syntax:

fs.readdir( path, options, callback )

Parameters:

This method accept three parameters as mentioned above and described below:

• path: It holds the path of the directory from where the contents have to be read. It can be a String, Buffer or URL.
• options: It is an object that can be used to specify optional parameters that will affect the method. It has two optional parameters:
  • encoding: It is a string value which specifies which encoding would be used for the filenames given to the callback argument. The default value is 'utf8'.
  • withFileTypes: It is a boolean value which specifies whether the files would be returned as fs.Dirent objects. The default value is 'false'.
• callback: It is the function that would be called when the method is executed.
  • err: It is an error that would be thrown if the operation fails.
  • files: It is an array of String, Buffer or fs.Dirent objects that contain the files in the directory.

Below examples illustrate the fs.readdir() method in Node.js:

Example 1: Basic Usage of fs.readdir()

This example demonstrates how to use the fs.readdir() method to return filenames in a directory.

Output:

Current directory filenames:
index.js
package.json
text_file_a.txt
text_file_b.txt

Current directory files:
Dirent { name: 'index.js', [Symbol(type)]: 1 }
Dirent { name: 'package.json', [Symbol(type)]: 1 }
Dirent { name: 'text_file_a.txt', [Symbol(type)]: 1 }
Dirent { name: 'text_file_b.txt', [Symbol(type)]: 1 }

Example 2: Using withFileTypes Option

Here’s an example where the withFileTypes option is set to true, and the results are returned as fs.Dirent objects.

Output:

Filenames with the .txt extension:
text_file_a.txt
text_file_b.txt

Handling Errors in fs.readdir()

When using fs.readdir(), various issues can arise, such as incorrect paths or insufficient permissions. Here's how to handle errors gracefully:

Example 1: Handling Invalid Directory Path

Output:

Error reading directory: ENOENT: no such file or directory, scandir 'C:\invalid\path'

Example 2: Handling Permission Issues

If the application doesn't have permission to read a directory, it will throw a permission error::

Output:

Permission error: ENOENT: no such file or directory, scandir 'C:\restricted\path'

Conclusion

The fs.readdir() method in Node.js is an efficient, non-blocking way to read the contents of a directory. It provides flexibility with options like withFileTypes to return file objects. Proper error handling is essential to avoid issues with invalid paths or permissions. It’s a straightforward method for managing file system operations in Node.js.