@bokuweb/zstd-wasm

zstd-wasm

Zstandard for browser, Node.js and Deno. For now support only simple API.

installation

npm install @bokuweb/zstd-wasm

examples

Node.js

Playground: https://runkit.com/bokuweb/60f1172a58aae5001aea2418

const { init, compress, decompress } = require('@bokuweb/zstd-wasm');

(async () => {
  await init();
  const compressed = compress(Buffer.from('Hello zstd!!'), 10);
  const res = decompress(compressed);
  Buffer.from(res).toString(); // Hello zstd!!
})();

Deno

See also, https://github.com/bokuweb/zstd-wasm/tree/master/examples/deno

import { init, decompress, compress } from 'https://deno.land/x/zstd_wasm/deno/zstd.ts';

await init();
const encoder = new TextEncoder();
const buffer = encoder.encode('Hello World');
const compressed = compress(buffer, 10);
const decompressed = decompress(compressed);
const decoder = new TextDecoder();
console.log(decoder.decode(decompressed));

without bundlers

import { init, compress, decompress } from '@bokuweb/zstd-wasm';

(async () => {
  await init('./zstd.wasm'); // Please deploy `node_modules/@bokuweb/zstd-wasm/lib/wasm/zstd.wasm` to your hosting server.
  const compressed = compress(Buffer.from('Hello zstd!!'), 10);
  const res = decompress(compressed);
  Buffer.from(res).toString(); // Hello zstd!!
})();

---

with webpack4

We need to use file-loader with webpack4. This is because, webpack doesn’t work well with wasm modules created with Emscripten. See, https://github.com/webpack/webpack/issues/7352

import { init, compress, decompress } from '@bokuweb/zstd-wasm';

(async () => {
  await init();
  const compressed = compress(Buffer.from('Hello zstd!!'), 10);
  const res = decompress(compressed);
  Buffer.from(res).toString(); // Hello zstd!!
})();

In this case, please install file-loader by yourself.

• webpack.config.js

{
  // ...snipped
  module: {
    rules: [
      {
        test: /zstd\.wasm$/,
        type: 'javascript/auto',
        loader: 'file-loader', // Please use file loader
      },
    ],
  },
}

---

with webpack5

We need to use Asset Modules with webpack5. This is because, webpack doesn’t work well with wasm modules created with Emscripten. See, https://github.com/webpack/webpack/issues/7352

import { init, compress, decompress } from '@bokuweb/zstd-wasm';

(async () => {
  await init();
  const compressed = compress(Buffer.from('Hello zstd!!'), 10);
  const res = decompress(compressed);
  Buffer.from(res).toString(); // Hello zstd!!
})();

• webpack.config.js

{
  // ...snipped
  module: {
    rules: [
      {
        test: /zstd\.wasm/,
        type: 'asset/resource',
      },
    ],
  },
  // ...snipped
}

Using dictionary

1. Create the dictionary

zstd --train FullPathToTrainingSet/* -o dictionaryName

2. Compress with dictionary

const dict = readFileSync('./dict');
const compressed = compressUsingDict(createCCtx(), buffer, dict, 10);

3. Decompress with dictionary

const dict = readFileSync('./dict');
const decompressed = decompressUsingDict(createDCtx(), buffer, dict);

See also example

API

async init(path?: string): Promise

Initialize module. Please specify path to zstd.wasm without bunders on browser.

compress(buffer: ArrayBuffer, compressionLevel?: number): ArrayBuffer

• buffer: data to compress.
• compressionLevel: (optional) compression level, default value is 3

Example:

const compressed = compress(buffer, 10);

decompress(buffer: ArrayBuffer): ArrayBuffer

• buffer: data to decompress.

Example:

const decompressed = decompress(buffer);

compressUsingDict(cctx: number, buffer: ArrayBuffer, dict: ArrayBuffer, compressionLevel?: number): ArrayBuffer

• cctx: a pointer to compress context. please create cctx with createCCtx.
• buffer: data to compress.
• dict: dictionary data.
• compressionLevel: (optional) compression level, default value is 3

Example:

const dict = readFileSync('./dict');
const compressed = compressUsingDict(createCCtx(), buffer, dict, 10);

createCCtx(): number

• create a pointer to compress context.

decompressUsingDict(dctx: number, dict: ArrayBuffer): ArrayBuffer

• dctx: a pointer to decompress context. please create cctx with createDCtx.
• buffer: data to decompress.
• dict: dictionary data.

Example:

const dict = readFileSync('./dict');
const decompressed = decompressUsingDict(createDCtx(), buffer, dict);

createDCtx(): number

• create a pointer to decompress context.

License

TypeScript glue is provided under the MIT License, and the zstd is provided by Facebook under the BSD 3-Clause License.