crc-32

What is crc-32?

The crc-32 npm package is a JavaScript library for calculating CRC32 checksums. CRC32 is a checksum algorithm that generates a 32-bit hash of data, which can be used to verify the integrity of data during transmission or storage. This package provides functions to compute CRC32 checksums for strings and byte arrays.

What are crc-32's main functionalities?

CRC32 checksum from a string

This feature allows you to compute the CRC32 checksum of a given string. The 'crc32.str' function takes a string as input and returns the checksum as a signed 32-bit integer.

"use strict";
var crc32 = require('crc-32');
var str = 'Hello World';
var checksum = crc32.str(str);
console.log('Checksum for string:', checksum);

CRC32 checksum from a byte array

This feature allows you to compute the CRC32 checksum of a byte array. The 'crc32.buf' function takes a byte array (Uint8Array) as input and returns the checksum as a signed 32-bit integer.

"use strict";
var crc32 = require('crc-32');
var buf = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);
var checksum = crc32.buf(buf);
console.log('Checksum for byte array:', checksum);

Other packages similar to crc-32

crc

The 'crc' npm package is similar to 'crc-32' and provides CRC checksum calculation for multiple CRC algorithms, including CRC32. It offers a wider range of CRC algorithms compared to 'crc-32', which is focused solely on CRC32.

buffer-crc32

The 'buffer-crc32' npm package is another alternative that provides CRC32 checksum calculation. It is designed to work with Node.js buffers and can be used to append the checksum to the buffer. It is similar to 'crc-32' but with a focus on Node.js buffer compatibility.

README

crc32

Standard CRC-32 algorithm implementation in JS (for the browser and nodejs). Emphasis on correctness and performance.

Installation

With npm:

$ npm install crc-32

In the browser:

<script src="crc32.js"></script>

The script will manipulate module.exports if available (e.g. in a CommonJS require context). This is not always desirable. To prevent the behavior, define DO_NOT_EXPORT_CRC

Usage

In all cases, the relevant function takes a single argument representing data.

The return value is a signed 32-bit integer.

• CRC32.buf(byte array or buffer) assumes the argument is a set of 8-bit unsigned integers (e.g. nodejs Buffer or simple array of ints).

• CRC32.bstr(binary string) interprets the argument as a binary string where the i-th byte is the low byte of the UCS-2 char: str.charCodeAt(i) & 0xFF

• CRC32.str(string) interprets the argument as a standard JS string

For example:

> // var CRC32 = require('crc-32'); // uncomment this line if in node
> CRC32.str("SheetJS")                          // -1647298270
> CRC32.bstr("SheetJS")                         // -1647298270
> CRC32.buf([ 83, 104, 101, 101, 116, 74, 83 ]) // -1647298270

> [CRC32.str("\u2603"),  CRC32.str("\u0003")]   // [ -1743909036,  1259060791 ]
> [CRC32.bstr("\u2603"), CRC32.bstr("\u0003")]  // [  1259060791,  1259060791 ]
> [CRC32.buf([0x2603]),  CRC32.buf([0x0003])]   // [  1259060791,  1259060791 ]

Testing

make test will run the node-based tests.

To run the in-browser tests, run a local server and go to the ctest directory. To update the browser artifacts, run make ctest.

License

Please consult the attached LICENSE file for details. All rights not explicitly granted by the Apache 2.0 license are reserved by the Original Author.

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