Node.js File System Operations:

What is File System Operations in Node.js

Doing operations on the file system is one of the most common tasks in Node.js application. File streams enable you to handle large files such as those found in reading or writing data in chunks and not loading all the contents into memory.

Reading from and Writing to Files:

Reading from a File:

                                                    
                                                    const fs = require('fs');

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

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

Writing to a File:

                                                    
                                                    const fs = require('fs');

const content = 'This is some content to write to the file.';

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

// Synchronous file writing (avoid for large files)
try {
    fs.writeFileSync('example.txt', content, 'utf8');
    console.log('File written successfully.');
} catch (err) {
    console.error('Error writing to file:', err);
}

Working with Directories:

Creating a Directory:

                                                    
                                                    const fs = require('fs');

fs.mkdir('newDirectory', err => {
    if (err) {
        console.error('Error creating directory:', err);
        return;
    }
    console.log('Directory created successfully.');
});

Removing a Directory:

                                                    
                                                    const fs = require('fs');

fs.rmdir('directoryToRemove', err => {
    if (err) {
        console.error('Error removing directory:', err);
        return;
    }
    console.log('Directory removed successfully.');
});

File Streams:

For instance, when working with big files, we can use file streams rather than loading everything into memory at once thereby facilitating more efficiency.

Reading from a File Stream:

                                                    
                                                    const fs = require('fs');

const readStream = fs.createReadStream('largeFile.txt', 'utf8');

readStream.on('data', chunk => {
    console.log('Received chunk:', chunk);
});

readStream.on('end', () => {
    console.log('File reading complete.');
});

readStream.on('error', err => {
    console.error('Error reading file:', err);
});

Writing to a File Stream:

                                                    
                                                    const fs = require('fs');

const writeStream = fs.createWriteStream('output.txt', 'utf8');

writeStream.write('Data to write\n');
writeStream.write('More data to write\n');

writeStream.end('End of data');

writeStream.on('finish', () => {
    console.log('Data written to file.');
});

writeStream.on('error', err => {
    console.error('Error writing to file:', err);
});

Node’s built-in fs module provides methods for working with the file system like reading from and writing to files, manipulating directories and managing file streams.