File System Basics in Node.js

Node.js provides a built-in fs module that allows you to interact with the file system. To get started, you need to require the module:

const fs = require("fs");

1. Reading Files

Synchronous File Reading

const data = fs.readFileSync("file.txt", "utf8");
console.log(data);

Asynchronous File Reading

fs.readFile("file.txt", "utf8", (err, data) => {
  if (err) throw err;
  console.log(data);
});

2. Writing Files

Synchronous File Writing

fs.writeFileSync("newfile.txt", "Hello, Node.js!", "utf8");

Asynchronous File Writing

fs.writeFile("newfile.txt", "Hello, Node.js!", "utf8", (err) => {
  if (err) throw err;
  console.log("File written successfully.");
});

3. Checking if a File Exists

fs.access("file.txt", fs.constants.F_OK, (err) => {
  if (err) {
    console.error("File does not exist.");
    return;
  }
  console.log("File exists.");
});

4. Renaming and Moving Files

fs.rename("oldfile.txt", "newfile.txt", (err) => {
  if (err) throw err;
  console.log("File renamed successfully.");
});

5. Deleting Files

fs.unlink("file.txt", (err) => {
  if (err) throw err;
  console.log("File deleted successfully.");
});

6. Working with Directories

Creating a Directory

fs.mkdir("myfolder", (err) => {
  if (err) throw err;
  console.log("Directory created successfully.");
});

Removing a Directory

fs.rmdir("myfolder", (err) => {
  if (err) throw err;
  console.log("Directory deleted successfully.");
});

7. Listing Files in a Directory

fs.readdir("myfolder", (err, files) => {
  if (err) throw err;
  console.log("Files in directory:", files);
});

File System Cheatsheet

Here's a quick reference cheatsheet for common file system operations in Node.js:

Reading Files:

• Synchronous: fs.readFileSync(path, encoding)
• Asynchronous: fs.readFile(path, encoding, callback)

Writing Files:

• Synchronous: fs.writeFileSync(path, data, encoding)
• Asynchronous: fs.writeFile(path, data, encoding, callback)

Checking File Existence:

• fs.access(path, fs.constants.F_OK, callback)

Renaming and Moving Files:

• fs.rename(oldPath, newPath, callback)

Deleting Files:

• fs.unlink(path, callback)

Working with Directories:

• Creating a Directory: fs.mkdir(path, callback)
• Removing a Directory: fs.rmdir(path, callback)
• Listing Files in a Directory: fs.readdir(path, callback)

Conclusion

Node.js's fs module provides a wide range of file system operations, making it a powerful tool for handling files and directories in your applications. With this guide and cheatsheet, you now have a solid understanding of the basics of file system operations in Node.js. Whether you're building a file uploader, a file manager, or simply reading and writing data, Node.js makes it straightforward and efficient.