zlib.crc32

zlib.crc32(data, value?): integer

Computes a 32-bit Cyclic Redundancy Check checksum of data. If value is specified, it is used as the starting value of the checksum, otherwise, 0 is used as the starting value.

The CRC algorithm is designed to compute checksums and to detect error in data transmission. It's not suitable for cryptographic authentication.

To be consistent with other APIs, if the data is a string, it will be encoded with UTF-8 before being used for computation. If users only use Node.js to compute and match the checksums, this works well with other APIs that uses the UTF-8 encoding by default.

Some third-party JavaScript libraries compute the checksum on a string based on str.charCodeAt() so that it can be run in browsers. If users want to match the checksum computed with this kind of library in the browser, it's better to use the same library in Node.js if it also runs in Node.js. If users have to use zlib.crc32() to match the checksum produced by such a third-party library:

1. If the library accepts Uint8Array as input, use TextEncoder in the browser to encode the string into a Uint8Array with UTF-8 encoding, and compute the checksum based on the UTF-8 encoded string in the browser.
2. If the library only takes a string and compute the data based on str.charCodeAt(), on the Node.js side, convert the string into a buffer using Buffer.from(str, 'utf16le').

import zlib from 'node:zlib';
import { Buffer } from 'node:buffer';

let crc = zlib.crc32('hello');  // 907060870
crc = zlib.crc32('world', crc);  // 4192936109

crc = zlib.crc32(Buffer.from('hello', 'utf16le'));  // 1427272415
crc = zlib.crc32(Buffer.from('world', 'utf16le'), crc);  // 4150509955

const zlib = require('node:zlib');
const { Buffer } = require('node:buffer');

let crc = zlib.crc32('hello');  // 907060870
crc = zlib.crc32('world', crc);  // 4192936109

crc = zlib.crc32(Buffer.from('hello', 'utf16le'));  // 1427272415
crc = zlib.crc32(Buffer.from('world', 'utf16le'), crc);  // 4150509955