FS (File System) Module

The File System Access API provides a way to interact with the file system, allowing web applications to read and write files on the user's device. This API is particularly useful for applications that need to save user data locally or allow users to upload and download files.

Key Concepts

• File Handles: Represent a reference to a file on the user's file system. They allow you to read from and write to the file.
• Directory Handles: Represent a reference to a directory on the user's file system. They allow you to read from and write to the directory, as well as access its contents.
• File Permissions: The API requires explicit permission from the user to read or write files, ensuring privacy and security.

Synchronous Methods

Synchronous methods block the execution of code until they complete, which can be simpler but may slow down your application if used excessively, especially for I/O operations.

info

These Methods:

• Block the event loop.

• Simpler to write.

• Suitable for quick scripts or tasks where performance is not critical.

These methods have ...Sync at the end of their names and block the event loop until they complete.

import * as fs from 'fs';

try {
  const data = fs.readFileSync('path/to/file.txt', 'utf8');
  console.log(data);
} catch (err) {
  console.error(err);
}

Asynchronous Methods

Asynchronous methods do not block the execution of code. They use callbacks to handle the result of the operation, making them suitable for non-blocking, event-driven programming.

info

These Methods:

• Use callbacks to handle results.

• Non-blocking, more efficient for I/O operations.

• Can lead to callback hell if not managed properly.

import * as fs from 'fs';

fs.readFile('path/to/file.txt', 'utf8', (err, data) => {
  if (err) {
    console.error(err);
    return;
  }
  console.log(data);
});

Promise-based Methods

Promise-based methods are part of the fs.promises API, providing a modern approach to asynchronous operations using promises, making the code more readable and easier to manage, especially with async/await.

info

These Methods:

• Use promises for handling results.

• Clean and readable, especially with async/await.

• Non-blocking and modern, preferred for scalable applications.

These methods are part of the fs.promises API and return promises, making them suitable for use with async/await.

import { promises as fs } from 'fs';

async function readFile(path: string) {
  try {
    const data = await fs.readFile(path, 'utf8');
    console.log(data);
  } catch (err) {
    console.error(err);
  }
}

readFile('path/to/file.txt');

Some of Most Used Methods

Sync	Async	Promise-based	Description
fs.readFileSync	fs.readFile	fs.promises.readFileSync	Read files
fs.writeFileSync	fs.writeFile	fs.promises.writeFileSync	Write files
fs.appendFileSync	fs.appendFile	fs.promises.appendFileSync	Append to files
fs.unlinkSync	fs.unlink	fs.promises.unlinkSync	Delete files
fs.mkdirSync	fs.mkdir	fs.promises.mkdirSync	Create directories
fs.rmdirSync	fs.rmdir	fs.promises.rmdirSync	Delete directories
fs.accessSync	fs.access	fs.promises.accessSync	Check if a file or directory exists