Wasmer JS

This repository consists of multiple packages:

• Wasmer WASI

Wasmer WASI

Isomorphic Javascript library for interacting with WASI Modules in Node.js, the Browser and Deno

NPM

For instaling @wasmer/wasi run this command in your shell:

npm install --save @wasmer/wasi

And then import it in your server or client-side code with:

import { init, WASI } from '@wasmer/wasi';

Deno

This package is published in Deno in the wasm package, you can import it direclty with:

import { init, WASI } from 'https://deno.land/x/wasm/wasi.ts';

Usage

// This is needed to load the WASI library first (since is a Wasm module)
await init();

let wasi = new WASI({
  env: {
      // 'ENVVAR1': '1',
      // 'ENVVAR2': '2'
  },
  args: [
      // 'command', 'arg1', 'arg2'
  ],
});

const moduleBytes = fetch("https://deno.land/x/wasm/tests/demo.wasm");
const module = await WebAssembly.compileStreaming(moduleBytes);
// Instantiate the WASI module
await wasi.instantiate(module, {});

// Run the start function
let exitCode = wasi.start();
let stdout = wasi.getStdoutString();

 // This should print "hello world (exit code: 0)"
console.log(`${stdout}(exit code: ${exitCode})`);

Building

To build this library you will need to have installed in your system:

• Node.JS
• Rust
• wasm-pack
• wabt (for wasm-opt)
• binaryen (for wasm-strip)

npm i
npm run build

Testing

Build the pkg and run the tests:

npm run build
npm run test

Pending things to implement

Currently, the Wasmer WASI implementation is only able to execute WASI packages and read the stdout.

• API to interact with the in-memory filesystem

What is WebAssembly?

Quoting the WebAssembly site:

WebAssembly (abbreviated Wasm) is a binary instruction format for a stack-based virtual machine. Wasm is designed as a portable target for compilation of high-level languages like C/C++/Rust, enabling deployment on the web for client and server applications.

About speed:

WebAssembly aims to execute at native speed by taking advantage of common hardware capabilities available on a wide range of platforms.

About safety:

WebAssembly describes a memory-safe, sandboxed execution environment […].

License

The entire project is under the MIT License. Please read the LICENSE file.