Wasmer JS 
This repository consists of multiple packages:
Wasmer WASI
Isomorphic Javascript library for interacting with WASI Modules in Node.js, the Browser and Deno. The Javascript Package supports:
- WASI (with command args, envs and stdio)
- In-Memory filesystem (MemFS)
NPM
For instaling @wasmer/wasi run this command in your shell:
npm install --save @wasmer/wasiAnd then import it in your server or client-side code with:
import { init, WASI } from '@wasmer/wasi';Check the Node usage examples in https://github.com/wasmerio/wasmer-js/tree/main/examples/node
Deno
This package is published in Deno in the wasm package, you can import it directly with:
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
// 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
Typescript API
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<any>;
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:
npm i
npm run buildTesting
Build the pkg and run the tests:
npm run build
npm run testWhat 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.