What is Buffer in Node.js ?

Last Updated : 16 Oct, 2024

In Node, Buffer is used to store and manage binary data. Pure JavaScript is great with Unicode-encoded strings, but it does not handle binary data very well. It is not problematic when we perform an operation on data at the browser level but at the time of dealing with TCP stream and performing a read-write operation on the file system is required to deal with pure binary data.

To satisfy this need Node.js uses Buffer to handle the binary data. So in this article, we are going to know about buffer in Node.js.

What is Buffer in Node?

Buffer in Node is a built-in object used to perform operations on raw binary data. The buffer class allows us to handle the binary data directly.

Syntax:

const buf = Buffer.alloc(10); // Allocates a buffer of 10 bytes.

Generally, Buffer refers to the particular memory location in memory. Buffer and array have some similarities, but the difference is array can be any type, and it can be resizable. Buffers only deal with binary data, and it can not be resizable. Each integer in a buffer represents a byte. console.log() function is used to print the Buffer instance.

Buffer Methods:

No	Method	Description
1	Buffer.alloc(size)	It creates a buffer and allocates size to it.
2	Buffer.from(initialization)	It initializes the buffer with given data.
3	Buffer.write(data)	It writes the data on the buffer.
4	toString()	It read data from the buffer and returned it.
5	Buffer.isBuffer(object)	It checks whether the object is a buffer or not.
6	Buffer.length	It returns the length of the buffer.
7	Buffer.copy(buffer,subsection size)	It copies data from one buffer to another.
8	Buffer.slice(start, end=buffer.length)	It returns the subsection of data stored in a buffer.
9	Buffer.concat([buffer,buffer])	It concatenates two buffers.

Example: Basic Implementation of Node.js Buffers

Node

// Filename: index.js  // Different Method to create Buffer const buffer1 = Buffer.alloc(100); const buffer2 = new Buffer('GFG'); const buffer3 = Buffer.from([1, 2, 3, 4]);  // Writing data to Buffer buffer1.write("Happy Learning");  // Reading data from Buffer const a = buffer1.toString('utf-8'); console.log(a);  // Check object is buffer or not console.log(Buffer.isBuffer(buffer1));  // Check length of Buffer console.log(buffer1.length);  // Copy buffer const bufferSrc = new Buffer('ABC'); const bufferDest = Buffer.alloc(3); bufferSrc.copy(bufferDest);  const Data = bufferDest.toString('utf-8'); console.log(Data);  // Slicing data const bufferOld = new Buffer('GeeksForGeeks'); const bufferNew = bufferOld.slice(0, 4); console.log(bufferNew.toString());  // concatenate two buffer const bufferOne = new Buffer('Happy Learning '); const bufferTwo = new Buffer('With GFG'); const bufferThree = Buffer.concat([bufferOne, bufferTwo]); console.log(bufferThree.toString());

Run the index.js file using the following command:

node index.js

Output:

Happy Learning
true
100
ABC
Geek
Happy Learning With GFG

Buffers are highly efficient when dealing with large amounts of binary data or when performance is critical, as they bypass the overhead of encoding/decoding data into JavaScript's native string format.

Reference: https://nodejs.org/api/buffer.html