wasm

@rollup/plugin-wasm

🍣 A Rollup which allows importing and bundling WebAssembly modules.

WebAssembly Modules are imported asynchronous as base64 strings. Small modules can be imported synchronously.

Requirements

This plugin requires an LTS Node version (v8.0.0+) and Rollup v1.20.0+.

Install

Using npm:

npm install @rollup/plugin-wasm --save-dev

Usage

Create a rollup.config.js configuration file and import the plugin:

import wasm from '@rollup/plugin-wasm';

export default {
  input: 'src/index.js',
  output: {
    dir: 'output',
    format: 'cjs'
  },
  plugins: [wasm()]
};

Then call rollup either via the CLI or the API.

Options

sync

Type: Array[...String]
Default: null

Specifies an array of strings that each represent a WebAssembly file to load synchronously. See Synchronous Modules for a functional example.

WebAssembly Example

Given the following simple C file:

int main() {
  return 42;
}

Compile the file using emscripten, or the online WasmFiddle tool. Then import and instantiate the resulting file:

import wasm from './sample.wasm';

wasm({ ...imports }).then(({ instance }) => {
  console.log(instance.exports.main());
});

The WebAssembly is inlined as a base64 encoded string. At runtime the string is decoded and a module is returned.

Note: The base64 string that represents the WebAssembly within the bundle will be ~33% larger than the original file.

Synchronous Modules

Small modules (< 4KB) can be compiled synchronously by specifying them in the configuration.

wasm({
  sync: ['web/sample.wasm', 'web/foobar.wasm']
});

This means that the exports can be accessed immediately.

import module from './sample.wasm';

const instance = sample({ ...imports });

console.log(instance.exports.main());

Meta

CONTRIBUTING

LICENSE (MIT)