Node.js Buffers

Node.js Buffers

When working with raw binary data in Node.js, the Buffer class plays a key role. Unlike arrays, Buffers represent raw memory allocations outside the V8 heap, making them essential for handling binary data in operations such as file system interactions and TCP streams.

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JavaScript on its own does not handle binary data efficiently, which is why the Buffer class was introduced. The good part is that Buffer is a global class, so you can use it directly without importing the buffer module.

Creating Buffers in Node.js

There are several ways to create a Buffer, but the following three are the most common:

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1. Creating an uninitialized buffer

var buf = new Buffer(10);

This creates a buffer of 10 octets.

2. Creating a buffer from an array

var buf = new Buffer([10, 20, 30, 40, 50]);

This initializes a buffer with the values provided in the array.

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3. Creating a buffer from a string

var buf = new Buffer("Simply Easy Learning", "utf-8");

This creates a buffer from a given string, with an optional encoding (default is UTF-8).

Writing to Buffers

To write data into a buffer, Node.js provides the write() method.

Syntax:

buf.write(string[, offset][, length][, encoding])

• string: Data to be written into the buffer.
• offset: Position to start writing. Default is 0.
• length: Number of bytes to write. Default is the buffer’s length.
• encoding: Encoding type. Default is utf8.

Return Value:
Returns the number of octets written. If the buffer doesn’t have enough space, only part of the string will be written.

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Example:
File: main.js

buf = new Buffer(256);  
len = buf.write("Simply Easy Learning");  
console.log("Octets written : " + len);

Run the file using:

node main.js

Output:

Octets written : 20

Reading from Buffers

To read data from a buffer, we use the toString() method.

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Syntax:

buf.toString([encoding][, start][, end])

• encoding: Character encoding (default is utf8).
• start: Starting index (default is 0).
• end: Ending index (default is the complete buffer).

Return Value:
Returns a decoded string from the buffer data.

Example:
File: main.js

buf = new Buffer(26);  
for (var i = 0; i < 26; i++) {  
  buf[i] = i + 97;  
}  

console.log(buf.toString('ascii'));        // abcdefghijklmnopqrstuvwxyz  
console.log(buf.toString('ascii', 0, 5));  // abcde  
console.log(buf.toString('utf8', 0, 5));   // abcde  
console.log(buf.toString(undefined, 0, 5));// defaults to utf8 -> abcde

Run the file using:

node main.js

Output:

abcdefghijklmnopqrstuvwxyz
abcde
abcde
abcde

Would you like me to also add a section on updating/deprecations (like using Buffer.alloc and Buffer.from instead of new Buffer()) since new Buffer() is deprecated in modern Node.js? That will make the article more up-to-date and professional for UpdateGadh.

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