adler32-umd

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adler32-umd is a pure-JavaScript UMD implementation of the Adler-32 checksum algorithm. This library utilizes the UMD pattern so that it works in Node.js, AMD, and browser globals.

Installation

Downloading

For Node.js,

npm install git://github.com/hajimes/adler32-umd.git

For client-side,

bower install git://github.com/hajimes/adler32-umd.git

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For Node.js,

var adler32 = require('adler32-umd');

For AMD,

require.config({
  paths: {
    adler32: 'path/to/adler32-umd'
  }
});

require(['adler32'], function(adler32) {
  /* ... */
});

In a brower,

<!-- The following snippet publishes a global function adler32 -->
<script src="path/to/adler32-umd/adler32-umd.min.js"></script>

API

adler32([buffer], [checksum=1])

Returns the Adler-32 checksum value.

Usage:

var buffer = [0, 1, 2, 3, 4];

// simple
console.log(adler32(buffer));

// progressively
var checksum = adler32();
for (var i = 0; i < buffer.length; i++) {
  checksum = adler32(buffer.slice(i, i + 1), checksum);
}
console.log(checksum);

The first argument buffer can be any Array-like object (e.g., built-in arrays, typed arrays in modern browers, and Buffer in Node.js) each of which element is an integer in the range of [0, 255]. If an element violates the range condition, the behavior of this function is unspecified. If buffer is undefined, the result value is the same as one when an empty buffer is given.

The second argument is an optional checksum value to be updated, which is useful for calculating the checksum of a byte stream progressively.

Parameters

[buffer]: byte[]|Uint8Array|Buffer, - byte buffer

[checksum=1]: number, - previously calculated checksum

Returns

number, Adler-32 checksum value

Other Pure-JavaScript Adler-32 Implementations

• https://github.com/BlueJeansAndRain/adler32 - with support for rolling checksums
• https://github.com/SheetJS/js-adler32 - with support for standard and binary string inputs

See Also

• [RFC 1950: ZLIB Compressed Data Format Specification version 3.3] (http://tools.ietf.org/html/rfc1950)
• zlib

License

Copyright (c) 2014 Hajime Senuma [email protected] under the MIT License.