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What is swap32() in Node.js Buffer Module?

Hammad Nasir

Grokking Modern System Design Interview for Engineers & Managers

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The swap32 function in Node.js Buffer Module

The swap32 function is a member function of Buffer class in the Node.js Buffer Module. The swap32 function is used to swap the byte order in place of a Buffer instance by considering it a 32-bit (or 4 bytes) array. The syntax of the swap32 function is as follows:

buf.swap32()

Parameters

swap32 takes no parameters.

Return value

  • Returns a reference to buf of type Buffer.

Description

The swap32 function reverses every 4-byte group present in the buffer buf by treating the buf as a 32-bit (or 4 bytes) array.

Example usage of the swap32 function

The following code snippet provides an example of how to use the swap32 function:

const b = Buffer.from([0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7]);
console.log("Buffer before swap32:")
console.log(b);

b.swap32()
console.log("Buffer after swap32:")
console.log(b);

In the example above, the first group of 4 bytes (00, 01, 02, 03) is reversed, resulting in the order 03, 02, 01, 00. For the second group of 4 bytes (04, 05, 06, 07) swapping results in the order 07, 06, 05, 04.

If the number of bytes is not enough to form 4-byte groups, then ERR_INVALID_BUFFER_SIZE error is thrown. Below is an example:

const b = Buffer.from([0x0, 0x1, 0x2, 0x3, 0x4, 0x5]);
console.log("Buffer before swap32:")
console.log(b);

b.swap32()
console.log("Buffer after swap32:")
console.log(b);

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Hammad Nasir
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Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

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