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Jeferson Eiji
Jeferson Eiji

Posted on • Originally published at dev.to

Understanding Buffers in Node.js: When and Why to Use Them

What Are Buffers in Node.js?

  • Buffers are a built-in class in Node.js designed to handle raw binary data.
  • They are similar to arrays of integers but store raw binary data instead of regular JavaScript numbers.
  • Buffers are especially important in Node.js because many operations involve dealing with streams of binary data (like files, network streams, etc.).

Why Not Use Regular JS Arrays?

  • JavaScript strings and arrays are not suitable for handling raw binary data because they use UTF-16 encoding and may not support arbitrary byte sequences reliably.

When Would You Use Buffers?

  • When working directly with TCP streams (e.g., implementing network protocols)
  • Reading or writing files in binary mode (like images, videos, or other non-text files)
  • Processing incoming HTTP requests containing binary data (e.g., file uploads)
  • Manipulating data from hardware devices or binary communication.

Example: Reading a File into a Buffer

const fs = require('fs');
const buffer = fs.readFileSync('image.png');
console.log(buffer); // Prints raw bytes of the image file
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Key Buffer Methods

  • Buffer.from(array) – Create a buffer from an array
  • buffer.toString([encoding]) – Convert buffer into a string
  • buffer.slice(start, end) – Extract part of the buffer
  • buffer.length – Get length in bytes

Use buffers when you need precise, efficient manipulation of binary data in Node.js applications.

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