What is File System Module in Node.js ?

Last Updated : 10 Jul, 2024

Node.js is a powerful platform for building server-side applications, and one of its key features is its ability to interact with the file system. The File System (fs) module in Node.js provides an extensive API to work with files and directories, allowing developers to perform operations such as reading, writing, updating, and deleting files and directories. This article provides a comprehensive overview of the fs module, its features, and how to use it effectively in your applications.

File System (fs) Module in Node

The File System module, abbreviated as fs, is a core module in Node.js that allows you to interact with the file system in a way modeled on standard POSIX functions. It provides both synchronous and asynchronous methods for various file operations. The asynchronous methods are non-blocking, which means the file operations are executed in the background, allowing the application to continue running other tasks.

Key Features of the `fs` Module

File Reading and Writing: Easily read from and write to files, supporting both text and binary data.
File Manipulation: Create, delete, rename, and move files and directories.
File Statistics: Retrieve detailed information about files, such as size, creation date, and permissions.
Stream Handling: Efficiently handle large files and data streams.

Importing the `fs` Module

To use the fs module in your Node.js application, you first need to import it using the require function:

const fs = require('fs');

Common Operations with the `fs` Module

The basic operations performed using the fs module are:

Table of Content

Reading Files

Asynchronous Reading

Use fs.readFile to read the contents of a file asynchronously. The function takes the file path, encoding, and a callback function to handle the result.

const fs = require('fs');

fs.readFile('example.txt', 'utf8', (err, data) => {
  if (err) {
    console.error('Error reading file:', err);
    return;
  }
  console.log('File content:', data);
});

Synchronous Reading

Use fs.readFileSync for synchronous file reading. This method blocks the execution until the file is completely read.

const fs = require('fs');

try {
  const data = fs.readFileSync('example.txt', 'utf8');
  console.log('File content:', data);
} catch (err) {
  console.error('Error reading file:', err);
}

Writing Files

Asynchronous Writing

Use fs.writeFile to write data to a file asynchronously. If the file does not exist, it will be created.

const fs = require('fs');

const content = 'Hello, Node.js!';

fs.writeFile('example.txt', content, 'utf8', (err) => {
  if (err) {
    console.error('Error writing file:', err);
    return;
  }
  console.log('File written successfully!');
});

Synchronous Writing

Use fs.writeFileSync to write data to a file synchronously.

const fs = require('fs');

const content = 'Hello, Node.js!';

try {
  fs.writeFileSync('example.txt', content, 'utf8');
  console.log('File written successfully!');
} catch (err) {
  console.error('Error writing file:', err);
}

Appending to Files

Asynchronous Appending

Use fs.appendFile to add data to the end of a file asynchronously.

const fs = require('fs');

const additionalContent = '\nAppended content.';

fs.appendFile('example.txt', additionalContent, 'utf8', (err) => {
  if (err) {
    console.error('Error appending to file:', err);
    return;
  }
  console.log('Content appended successfully!');
});

Synchronous Appending

Use fs.appendFileSync to append data to a file synchronously.

const fs = require('fs');

const additionalContent = '\nAppended content.';

try {
  fs.appendFileSync('example.txt', additionalContent, 'utf8');
  console.log('Content appended successfully!');
} catch (err) {
  console.error('Error appending to file:', err);
}

Reading Directory Contents

Asynchronous Directory Reading

Use fs.readdir to read the contents of a directory asynchronously.

const fs = require('fs');

fs.readdir('new_directory', (err, files) => {
  if (err) {
    console.error('Error reading directory:', err);
    return;
  }
  console.log('Directory contents:', files);
});

Synchronous Directory Reading

Use fs.readdirSync to read the contents of a directory synchronously.

const fs = require('fs');

try {
  const files = fs.readdirSync('new_directory');
  console.log('Directory contents:', files);
} catch (err) {
  console.error('Error reading directory:', err);
}

Conclusion

The File System module in Node.js provides a comprehensive API for working with the file system. Whether you need to read, write, manipulate files, or get detailed information about them, the fs module has you covered. It supports both synchronous and asynchronous operations, allowing you to choose the best method for your application based on performance and complexity needs.

What are Modules in Node.js ?

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