numcodecs.js

Buffer compression and transformation codecs for use in Zarr.js and beyond...

Installation

npm install numcodecs

Usage

import { Blosc, GZip, Zlib, LZ4, Zstd } from 'numcodecs';

const codec = new Blosc(); 
// or Blosc.fromConfig({ clevel: 5, cname: 'lz4', shuffle: Blosc.SHUFFLE, blocksize: 0 });

const size = 100000;
const arr = new Uint32Array(size);
for (let i = 0; i < size; i++) {
  arr[i] = i;
}

const bytes = new Uint8Array(arr.buffer);
console.log(bytes);
// Uint8Array(400000) [0, 0, 0, 0,  1, 0, 0, 0,  2, 0, 0, 0, ... ]

const encoded = await codec.encode(bytes);
console.log(encoded);
// Uint8Array(3744) [2, 1, 33, 4, 128, 26, 6, 0, 0, 0, 4, 0, ... ]

const decoded = await codec.decode(encoded);
console.log(new Uint32Array(decoded.buffer));
// Uint32Array(100000) [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,  ... ]

Author's note

This project is an incomplete TypeScript implementation of the buffer compression library numcodecs. The following codecs are currently supported:

• blosc
• gzip
• lz4
• zlib
• zstd

Package exports

Each compressor is bundled as the default export of separate code-split submodules. This makes it easy to import each module independently in your applications or from a ESM-friendly CDN like skypack.

// index.js
const Zlib = require('numcodecs/zlib');

// index.mjs
import Zlib from 'numcodecs/zlib';

// In the browser...
import Zlib from 'https://cdn.skypack.dev/numcodecs/zlib';

Development

$ git clone https://github.com/manzt/numcodecs.js.git 
$ cd numcodecs.js
$ npm install && npm run test

The <codec_name>.js + <codec_name>.wasm source for each WASM-based codec are generated with Docker with the following commands:

cd codecs/<codec_name>
npm run build

Publishing

$ npm version [<newversion> | major | minor | patch]
$ npm run build # bundles source & copies README.md + package.json to dist/
$ cd dist
$ npm publish