@lichtblick/wasm-zstd

https://github.com/facebook/zstd compiled to WebAssembly and exposed as a high-level TypeScript/JavaScript API . PRs welcome!

API

@lichtblick/wasm-zstd exports:

export const isLoaded: Promise<boolean>;
export function compressBound(size: number): number;
export function compress(buffer: Uint8Array, compressionLevel?: number): Buffer;
export function decompress(buffer: Uint8Array, size: number): Buffer;

Here is an example of compressing then decompressing with this library:

import fs from "fs/promises";
import zstd from "@lichtblick/wasm-zstd";

async function main() {
  const inputData = await fs.readFile("input.txt");

  // Wait for the wasm module to load
  await zstd.isLoaded;

  // Compress and save to a file with zstd compression level 3
  const compressedBytes = zstd.compress(inputData, 3);
  await fs.writeFile("compressed.zst", compressedBytes);

  // Currently you need to know the size of the output buffer so the wasm runtime
  // can allocate enough bytes to decompress into
  const outputSize = inputData.byteLength;

  // Decompress
  const decompressedBytes = zstd.decompress(compressedBytes, inputData.byteLength);
  assert(decompressedBytes.byteLength === inputData.byteLength);
}

Using the module in a browser

Emscripten compiled WebAssembly modules are built in 2 parts: a .js side and a .wasm side. In the browser the .js side needs to download the .wasm side from the server so it can compile it. There is more information available in the emscripten documentation.

Developing locally

1. Run yarn install to install dependencies.
2. Run yarn build to invoke emcc inside a Docker container and compile the code in wasm-zstd.c as well as the required zstd source files. The output will be in dist/ on the host machine.
3. Run yarn test to run the tests.

License

@lichtblick/wasm-zstd is licensed under the MIT License.

Releasing

1. Run yarn version --[major|minor|patch] to bump version
2. Run git push && git push --tags to push new tag
3. GitHub Actions will take care of the rest

Stay in touch

Join our Slack channel to ask questions, share feedback, and stay up to date on what our team is working on.