File System

The fs (File System) module in Node.js provides an API to interact with the file system, allowing developers to read, write, and manipulate files and directories on the system. It is a core module in Node.js, meaning it doesn’t need to be installed separately.

Reading and Writing Files with the fs Module

1. Reading Files

• Asynchronously: This method is non-blocking, so it doesn’t prevent other code from executing while it reads the file.

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

• Synchronously: This method is blocking, so it waits until the file is read completely before moving to the next line.

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

2. Writing Files

• Asynchronously:

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

• Synchronously:

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

Summary

• Use fs.readFile and fs.writeFile for non-blocking I/O operations.
• Use fs.readFileSync and fs.writeFileSync for simpler, blocking operations when the file size is small or when synchronous operation is necessary.

This module is versatile for handling file-related tasks, including creating, reading, updating, and deleting files.