A standalone JavaScript implementation of the Lempel-Ziv-Markov chain (LZMA) compression algorithm
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LZMA in a Browser

LZMA.JS is a JavaScript implementation of the Lempel-Ziv-Markov chain (LZMA) compression algorithm. The JavaScript, CSS, and HTML is licensed under the MIT license. See LICENSE for more details.

It is based on gwt-lzma, which is a port of the LZMA SDK from Java into JavaScript. The original Java code is licensed under the Apache License 2.0 license.

Because it is based on a GWT module, the code is unfortunately very difficult to read. Help cleaning up the code and making it readable would be appreciated. It could also be optimized quite a bit.

Live demos can be found here.

How to Use

First, load the bootstraping code.

/// In a browser:
<script src="../src/lzma.js"></script>

/// In node:
var LZMA = require("../src/lzma.js").LZMA;

Create the LZMA object.

/// LZMA([optional path])
/// If lzma_worker.js is in the same director, you don't need to set the path.
/// You should be able to do the first two steps simultaneously in Node.js: var my_lzma = require("../src/lzma.js").LZMA();
var my_lzma = new LZMA("../src/lzma_worker.js");

(De)Compress stuff.

/// To compress:
///NOTE: mode can be 1-9 (1 is fast but not as good; 9 will probably make your browser crash).
my_lzma.compress(string, mode, on_finish(result) {}, on_progress (percent) {});

/// To decompress:
my_lzma.decompress(byte_array, on_finish(result) {}, on_progress (percent) {});

Node.js Installation

LZMA.JS is available in the npm repository. If you have npm installed, you can install it by running

$ npm install lzma

and load it with the following code:

var my_lzma = require("lzma").LZMA();


The calls to compress() and decompress() are asynchronous, so you need to supply a callback function if you want to use the (de)compressed data. There was a synchronous version, which you can find in the archives, but it is no longer maintained.

LZMA.JS will use web workers if they are available. If the environment does not support web workers, it will create a few global functions (Worker(), onmessage(), and postMessage()) to mimic the functionality.