File System in Node.js

The fs (file system) module provides a set of methods to interact with the file system.

It allows us to perform various file-related operations, such as reading from and writing to files, creating directories, and more.

Here are file system operations using the "fs" module:

Reading from a File using "fs" module:

Reading the contents of a file asynchronously using "fs.readFile()".

Example:

const fs = require('fs');

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

  console.log(`File Contents: ${data}`);
});

Writing to a File:

Writing data to a file asynchronously using "fs.writeFile()".

Example:

const fs = require('fs');

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

fs.writeFile('output.txt', content, 'utf8', (err) => {
  if (err) {
    console.error(`Error writing to file: ${err.message}`);
    return;
  }

  console.log('Data written to the file successfully.');
});

Reading from a File Synchronously:

Reading the contents of a file synchronously using "fs.readFileSync()". readFileSync() method is a synchronous method. Node.js uses a single-threaded approach, this function will block the main thread until the function executes successfully. Node.js Server will not take any new request from the client until `fs.readFileSync` executes completely.

Example:

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.message}`);
}

The Better approach is to use an asynchronous function in node.js, so it wouldn't block the main thread from taking new requests from client.

Writing to a File Synchronously:

Writing data to a file synchronously using "fs.writeFileSync()". fs.writeFileSync() method is a synchronous method. Node.js uses a single-threaded approach, this function will block the main thread until the function executes successfully. Node.js Server will not take any new request from the client until `fs.writeFileSync` executes completely.

Example:

const fs = require('fs');

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

try {
  fs.writeFileSync('output.txt', content, 'utf8');
  console.log('Data written to file successfully.');
} catch (err) {
  console.error(`Error writing to file: ${err.message}`);
}

The Better approach is to use an asynchronous function in node.js, so it wouldn't block the main thread from taking new requests from client.

Checking if a File or Directory Exists:

Checking if a file or directory exists using "fs.existsSync()".

Example:

const fs = require('fs');

const filePath = 'example.txt';

if (fs.existsSync(filePath)) {
  console.log(`${filePath} exists.`);
} else {
  console.log(`${filePath} does not exist.`);
}

Creating a Directory:

Creating a directory asynchronously using "fs.mkdir()".

Example:

const fs = require('fs');

fs.mkdir('new_directory', (err) => {
  if (err) {
    console.error(`Error creating directory: ${err.message}`);
    return;
  }

  console.log('Directory created successfully.');
});

Listing Files in a Directory:

Listing files in a directory asynchronously using "fs.readdir()".

Example:

const fs = require('fs');

const directoryPath = './';

fs.readdir(directoryPath, (err, files) => {
  if (err) {
    console.error(`Error reading directory: ${err.message}`);
    return;
  }

  console.log('Files in the directory:');
  files.forEach((file) => {
    console.log(file);
  });
});

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