1. Introduction

In this tutorial, we will explore the concept of file streams and buffers in Node.js. File streams allow us to work with large files by breaking them into smaller, manageable pieces. Buffers, on the other hand, provide us with a way to store and manipulate binary data.

By the end of this tutorial, you will learn how to read and write files efficiently using streams and manipulate data using buffers.

Prerequisites

You should have a basic understanding of JavaScript and Node.js. It would be beneficial if you are familiar with ES6 syntax and asynchronous programming in JavaScript.

2. Step-by-Step Guide

Understanding Streams and Buffers

A stream in Node.js is an abstract interface for working with streaming data. Streams can be readable, writable, or both. They allow you to work with large amounts of data efficiently because they divide the data into chunks.

A buffer, on the other hand, is a temporary storage spot for data being moved from one place to another. It's specifically designed to handle binary data.

Reading Files using Streams

To read files using streams, we use the createReadStream method of the fs module. It creates a readable stream to the file.

const fs = require('fs');

const readStream = fs.createReadStream('./largefile.txt');

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

In this example, we are listening for data events on the read stream. When a chunk of data is available, it's logged to the console.

Writing Files using Streams

To write files using streams, we use the createWriteStream method of the fs module.

const fs = require('fs');

const readStream = fs.createReadStream('./largefile.txt');
const writeStream = fs.createWriteStream('./output.txt');

readStream.on('data', (chunk) => {
    writeStream.write(chunk);
});

In this example, we are reading a large file in chunks and writing those chunks to another file.

3. Code Examples

Working with Buffers

Buffers are used to store binary data. Here's how you can create a buffer and manipulate data.

// Create a buffer of size 10 bytes
const buffer = Buffer.alloc(10);

// Write data to the buffer
buffer.write('Hello');

console.log(buffer.toString());
// Output: Hello

In this example, we first allocate a new buffer of size 10 bytes. Then we write the string 'Hello' to the buffer. Finally, we convert the buffer back to a string and log it to the console.

4. Summary

In this tutorial, we've covered the basics of working with file streams and buffers in Node.js. We've learned how to read and write large files efficiently using streams and how to store and manipulate binary data using buffers.

You should now try to work with different file types and manipulate different kinds of data using buffers. You can also explore other types of streams like duplex and transform streams.

5. Practice Exercises

1. Write a script to copy a large image file using streams.
2. Write a script to convert a buffer containing the string 'Hello World' to upper case.
3. Write a script to read a CSV file using streams and print each line to the console.

Remember, the key to mastering these concepts is practice. Keep experimenting with different scenarios and try to solve more complex problems as you progress. Good luck!