The FileSystem module (fs) is a core module in Node.js, providing powerful capabilities for interacting with files programmatically. This module is helpful in various tasks, including managing configurations, handling data organization, and reading and writing file content.

📖 File Reading with fs.readFile

The fs.readFile method returns a promise that resolves with the file's contents. It allows for asynchronous file reading, making it suitable for reading text and binary files.

• path - the file path to read;
• options - an optional object specifying options like the encoding.

Imagine building a dynamic blogging platform. Here, the fs.readFile method steps onto the stage, quickly retrieving blog post content from a file.

Code Example: Reading Content

Step by Step Explanation

🖋️ File Writing with fs.writeFile

The fs.writeFile method returns a promise that resolves when the file has been written. It is used to asynchronously write data to a file, which can be new or existing. It provides options for specifying the data, encoding, and file permissions.

• file - the file path to write to;
• data - the data to write, which can be a string or a buffer;
• options - an optional object specifying options like the encoding and file mode.

Imagine we need to save a new user to the user-db.json file. Here fs.writeFile method ensures our words find their place.

Code Example: Writing User Data

Step by Step Explanation

📄 Extending with fs.appendFile

The fs.appendFile method returns a promise that resolves when the data has been appended to the file. It is used to asynchronously append data to an existing file, preserving its prior content.

• file - the file path to which data will be appended;
• data - the data to append, which can be a string or a buffer;
• options - an optional object specifying options like the encoding and file mode.

Picture a bustling chat application recording conversations. As new messages flow, the fs.appendFile method adds new messages to the chat log while preserving the prior interactions.

Code Example: Appending Chat Messages

Step by Step Explanation

Note

• fs.writeFile is used to completely replace the content of a file or create a new file;
• fs.appendFile is used to add new data to the end of an existing file without overwriting what's already there.

🧐 Quiz Time

Let's gauge your understanding of FileSystem (fs) module concepts: