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.
The Javascript Package supports:
* [X] WASI (with command args, envs and stdio)
* [X] In-Memory filesystem (MemFS)

$3

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

``bash
npm install --save @wasmer/wasi
`

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

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

> Check the Node usage examples in https://github.com/wasmerio/wasmer-js/tree/main/examples/node

$3

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

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

> Check the Deno usage Examples in https://github.com/wasmerio/wasmer-js/tree/main/examples/deno

Usage

`js
// 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}));
`

API Docs

$3

`typescript
export class WASI {
constructor(config: any);
readonly fs: MemFS;

instantiate(module: any, imports: object): WebAssembly.Instance;
// Start the WASI Instance, it returns the status code when calling the start
// function
start(instance: WebAssembly.Instance): number;
// Get the stdout buffer
// Note: this method flushes the stdout
getStdoutBuffer(): Uint8Array;
// Get the stdout data as a string
// Note: this method flushes the stdout
getStdoutString(): string;
// Get the stderr buffer
// Note: this method flushes the stderr
getStderrBuffer(): Uint8Array;
// Get the stderr data as a string
// Note: this method flushes the stderr
getStderrString(): string;
// Set the stdin buffer
setStdinBuffer(buf: Uint8Array): void;
// Set the stdin data as a string
setStdinString(input: string): void;
}

export class MemFS {
constructor();
readDir(path: string): Array;
createDir(path: string): void;
removeDir(path: string): void;
removeFile(path: string): void;
rename(path: string, to: string): void;
metadata(path: string): object;
open(path: string, options: any): JSVirtualFile;
}

export class JSVirtualFile {
lastAccessed(): BigInt;
lastModified(): BigInt;
createdTime(): BigInt;
size(): BigInt;
setLength(new_size: BigInt): void;
read(): Uint8Array;
readString(): string;
write(buf: Uint8Array): number;
writeString(buf: string): number;
flush(): void;
seek(position: number): number;
}
`

Building

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

* Node.JS
* [Rust][Rust]
* [wasm-pack][wasm-pack]
* [wabt][wabt] (for wasm-strip)
* [binaryen][binaryen] (for wasm-opt)

`sh
npm i
npm run build
`

Testing

Build the pkg and run the tests:

`sh
npm run build
npm run test
`

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][license].

[license]: https://github.com/wasmerio/wasmer/blob/master/LICENSE
[Rust]: https://www.rust-lang.org/
[wasm-pack]: https://rustwasm.github.io/wasm-pack/
[wabt]: https://github.com/WebAssembly/wabt
[binaryen]: https://github.com/WebAssembly/binaryen