What is the preferred way to publish a wasm library on npm?

Publishing a WebAssembly (WASM) library to npm requires following several key steps to package your WASM code and any necessary JavaScript bridge code. Here is a simplified step-by-step guide:

1. Compile your code to WebAssembly:

   • If your code is written in C/C++ or Rust, you must use tools like Emscripten, wasm-pack, or others to compile it into WASM format.

2. Create an npm package:

   • Initialize your project by running npm init in the project root directory and providing the necessary details to generate a package.json file.

3. Write JavaScript bridge code:

   • Prepare JavaScript code so that users can easily import and use your WASM library. This may include writing a loader to asynchronously load the WASM module.

4. Prepare your package files:

   • Ensure that the WASM files and JavaScript bridge code are included in your npm package.
   • Create a README.md file to explain how to install and use your library.
   • Add a .npmignore file (if needed) to exclude unnecessary files from your package.

5. Write and run tests:

   • Before publishing, make sure to write tests to verify your library's functionality. You can utilize testing frameworks such as Jest or Mocha.

6. Log in to npm:

   • Use the npm login command to log in to your npm account.

7. Publish the package:

   • Use the npm publish command to publish your package to npm.

Here is an example package.json file for publishing an npm package that includes WASM files:

json
{
  "name": "your-wasm-library",
  "version": "1.0.0",
  "description": "A simple WASM library",
  "main": "index.js",
  "files": [
    "your_wasm_module.wasm",
    "index.js"
  ],
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [
    "wasm",
    "webassembly",
    "example"
  ],
  "author": "Your Name",
  "license": "ISC"
}

In your index.js file, you might have code similar to the following to asynchronously load the WASM file:

javascript
const path = require('path');
const fs = require('fs');

let wasmModule;

const loadWASM = async () => {
  if (!wasmModule) {
    const wasmPath = path.resolve(__dirname, 'your_wasm_module.wasm');
    const buffer = fs.readFileSync(wasmPath);
    const module = await WebAssembly.compile(buffer);
    const instance = await WebAssembly.instantiate(module);
    wasmModule = instance.exports;
  }
  return wasmModule;
};

module.exports = {
  loadWASM,
  // export other functions that use wasmModule
};

Remember to replace the placeholders in the above code and configuration (e.g., your-wasm-library, your_wasm_module.wasm, Your Name) with your actual library name, module name, and author name, respectively.

Make sure to adhere to npm's versioning conventions for updating your package version and managing it properly. Before publishing, thoroughly review npm's documentation and best practices.