pako

What is pako?

The pako npm package is a high-speed zlib port to JavaScript which works in the browser and node.js. It provides compression and decompression functionalities using the zlib library, which is widely used for data compression.

What are pako's main functionalities?

Compression

This feature allows you to compress a string or binary data using pako's deflate method.

const pako = require('pako');
const input = 'String to compress';
const compressed = pako.deflate(input);

Decompression

This feature allows you to decompress data that was compressed using pako's deflate method or compatible zlib compression.

const pako = require('pako');
const compressed = new Uint8Array([]); // Use a previously compressed Uint8Array
const decompressed = pako.inflate(compressed);

Gzip Compression

This feature allows you to compress data using gzip, which is a file format and a software application used for file compression and decompression.

const pako = require('pako');
const input = 'String to compress';
const compressed = pako.gzip(input);

Gzip Decompression

This feature allows you to decompress data that was compressed using pako's gzip method.

const pako = require('pako');
const compressed = new Uint8Array([]); // Use a previously gzip compressed Uint8Array
const decompressed = pako.ungzip(compressed);

Other packages similar to pako

zlib

The zlib package is a core module in Node.js for compression/decompression. It is similar to pako but is built into Node.js and does not work in the browser without additional bundling or shimming.

jszip

JSZip is a library for creating, reading, and editing .zip files with JavaScript, with a lovely and simple API. While pako focuses on zlib compression, JSZip provides additional functionalities to handle zip files.

compressjs

Compressjs is a pure JavaScript implementation of various data compression algorithms, such as Huffman coding and Burrows-Wheeler transform. It offers a wider range of algorithms than pako, but it might not be as optimized for speed.

fflate

fflate is a high-performance, low-level deflate/inflate compression library that is faster than pako on most benchmarks. It is a newer library that focuses on performance and efficiency.

README

pako

zlib port to javascript, very fast!

Why pako is cool:

• Almost as fast in modern JS engines as C implementation (see benchmarks).
• Works in browsers, you can browserify any separate component.
• Chunking support for big blobs.
• Results are binary equal to well known zlib (now contains ported zlib v1.2.8).

This project was done to understand how fast JS can be and is it necessary to develop native C modules for CPU-intensive tasks. Enjoy the result!

Famous projects, using pako:

• browserify (via browserify-zlib)
• JSZip
• mincer
• JS-Git and Tedit by @creationix

Benchmarks:

node v0.10.26, 1mb sample:

   deflate-dankogai x 4.73 ops/sec ±0.82% (15 runs sampled)
   deflate-gildas x 4.58 ops/sec ±2.33% (15 runs sampled)
   deflate-imaya x 3.22 ops/sec ±3.95% (12 runs sampled)
 ! deflate-pako x 6.99 ops/sec ±0.51% (21 runs sampled)
   deflate-pako-string x 5.89 ops/sec ±0.77% (18 runs sampled)
   deflate-pako-untyped x 4.39 ops/sec ±1.58% (14 runs sampled)
 * deflate-zlib x 14.71 ops/sec ±4.23% (59 runs sampled)
   inflate-dankogai x 32.16 ops/sec ±0.13% (56 runs sampled)
   inflate-imaya x 30.35 ops/sec ±0.92% (53 runs sampled)
 ! inflate-pako x 69.89 ops/sec ±1.46% (71 runs sampled)
   inflate-pako-string x 19.22 ops/sec ±1.86% (49 runs sampled)
   inflate-pako-untyped x 17.19 ops/sec ±0.85% (32 runs sampled)
 * inflate-zlib x 70.03 ops/sec ±1.64% (81 runs sampled)

node v0.11.12, 1mb sample:

   deflate-dankogai x 5.60 ops/sec ±0.49% (17 runs sampled)
   deflate-gildas x 5.06 ops/sec ±6.00% (16 runs sampled)
   deflate-imaya x 3.52 ops/sec ±3.71% (13 runs sampled)
 ! deflate-pako x 11.52 ops/sec ±0.22% (32 runs sampled)
   deflate-pako-string x 9.53 ops/sec ±1.12% (27 runs sampled)
   deflate-pako-untyped x 5.44 ops/sec ±0.72% (17 runs sampled)
 * deflate-zlib x 14.05 ops/sec ±3.34% (63 runs sampled)
   inflate-dankogai x 42.19 ops/sec ±0.09% (56 runs sampled)
   inflate-imaya x 79.68 ops/sec ±1.07% (68 runs sampled)
 ! inflate-pako x 97.52 ops/sec ±0.83% (80 runs sampled)
   inflate-pako-string x 45.19 ops/sec ±1.69% (57 runs sampled)
   inflate-pako-untyped x 24.35 ops/sec ±2.59% (40 runs sampled)
 * inflate-zlib x 60.32 ops/sec ±1.36% (69 runs sampled)

zlib's test is partially affected by marshalling (that make sense for inflate only). You can change deflate level to 0 in benchmark source, to investigate details. For deflate level 6 results can be considered as correct.

Install:

node.js:

npm install pako

browser:

bower install pako

Example & API

Full docs - http://nodeca.github.io/pako/

var pako = require('pako');

// Deflate
//
var input = new Uint8Array();
//... fill input data here
var output = pako.deflate(input);

// Inflate (simple wrapper can throw exception on broken stream)
//
var compressed = new Uint8Array();
//... fill data to uncompress here
try {
  var result = pako.inflate(compressed);
} catch (err) {
  console.log(err);
}

//
// Alternate interface for chunking & without exceptions
//

var inflator = new pako.Inflate();

inflator.push(chunk1, false);
inflator.push(chunk2, false);
...
inflator.push(chunkN, true); // true -> last chunk

if (inflator.err) {
  console.log(inflator.msg);
}

var output = inflator.result;

Sometime you can wish to work with strings. For example, to send big objects as json to server. Pako detects input data type. You can force output to be string with option { to: 'string' }.

var pako = require('pako');

var test = { my: 'super', puper: [456, 567], awesome: 'pako' };

var binaryString = pako.deflate(JSON.stringify(test), { to: 'string' });

//
// Here you can do base64 encode, make xhr requests and so on.
//

var restored = JSON.parse(pako.inflate(binaryString, { to: 'string' }));

Notes

Pako does not contain some specific zlib functions:

• deflate - methods deflateCopy, deflateBound, deflateParams, deflatePending, deflatePrime, deflateTune.
• inflate - methods inflateCopy, inflateMark, inflatePrime, inflateGetDictionary, inflateSync, inflateSyncPoint, inflateUndermine.
• High level inflate/deflate wrappers (classes) may not support some flush modes. Those should work: Z_NO_FLUSH, Z_FINISH, Z_SYNC_FLUSH.

Authors

• Andrey Tupitsin @anrd83
• Vitaly Puzrin @puzrin

Personal thanks to:

• Vyacheslav Egorov (@mraleph) for his awesome tutorials about optimising JS code for v8, IRHydra tool and his advices.
• David Duponchel (@dduponchel) for help with testing.

Original implementation (in C):

• zlib by Jean-loup Gailly and Mark Adler.

License

• MIT - all files, except /lib/zlib folder
• ZLIB - /lib/zlib content