pako
==========================================
[](https://github.com/nodeca/pako/actions)
[](https://www.npmjs.org/package/pako)
> zlib port to javascript, very fast!
__Why pako is cool:__
- Results are binary equal to well known [zlib](http://www.zlib.net/) (now contains ported zlib v1.3.2).
- Almost as fast in modern JS engines as C implementation (see benchmarks).
- Works in browsers, you can browserify any separate component.
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!
__Benchmarks:__
node v24, 1mb input sample:
```
deflate-pako x 14.27 ops/sec ±3.41% (37 runs sampled)
deflate-pako-zlib-hash x 10.60 ops/sec ±0.50% (29 runs sampled)
deflate-zlib x 30.30 ops/sec ±0.61% (51 runs sampled)
gzip-pako x 13.48 ops/sec ±0.50% (36 runs sampled)
inflate-pako x 138 ops/sec ±1.26% (75 runs sampled)
inflate-zlib x 397 ops/sec ±1.37% (81 runs sampled)
ungzip-pako x 125 ops/sec ±1.46% (73 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:__
```
npm install pako
```
Examples / API
--------------
Full docs - http://nodeca.github.io/pako/
```javascript
const pako = require('pako');
// Deflate
//
const input = new Uint8Array();
//... fill input data here
const output = pako.deflate(input);
// Inflate (simple wrapper can throw exception on broken stream)
//
const compressed = new Uint8Array();
//... fill data to uncompress here
try {
const result = pako.inflate(compressed);
// ... continue processing
} catch (err) {
console.log(err);
}
//
// Alternate interface for chunking & without exceptions
//
const deflator = new pako.Deflate();
deflator.push(chunk1, false);
deflator.push(chunk2); // second param is false by default.
...
deflator.push(chunk_last, true); // `true` says this chunk is last
if (deflator.err) {
console.log(deflator.msg);
}
const output = deflator.result;
const inflator = new pako.Inflate();
inflator.push(chunk1);
inflator.push(chunk2);
...
inflator.push(chunk_last); // no second param because end is auto-detected
if (inflator.err) {
console.log(inflator.msg);
}
const output = inflator.result;
```
Sometime you can wish to work with strings. For example, to send
stringified objects to server. Pako's deflate detects input data type, and
automatically recode strings to utf-8 prior to compress. Inflate has special
option, to say compressed data has utf-8 encoding and should be recoded to
javascript's utf-16.
```javascript
const pako = require('pako');
const test = { my: 'super', puper: [456, 567], awesome: 'pako' };
const compressed = pako.deflate(JSON.stringify(test));
const restored = JSON.parse(pako.inflate(compressed, { 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.
Authors
-------
- Andrey Tupitsin [@anrd83](https://github.com/andr83)
- Vitaly Puzrin [@puzrin](https://github.com/puzrin)
Personal thanks to:
- Vyacheslav Egorov ([@mraleph](https://github.com/mraleph)) for his awesome
tutorials about optimising JS code for v8, [IRHydra](http://mrale.ph/irhydra/)
tool and his advices.
- David Duponchel ([@dduponchel](https://github.com/dduponchel)) for help with
testing.
Original implementation (in C):
- [zlib](http://zlib.net/) by Jean-loup Gailly and Mark Adler.
License
-------
- MIT - all files, except `/lib/zlib` folder
- ZLIB - `/lib/zlib` content