# @wasmer/wasi
> Isomorphic Javascript library for interacting with WASI Modules in Node.js and the Browser.
Latest version **1.2.2** (published 2022-12-01) · MIT license · 0 weekly downloads
## Install
```sh
npm install @wasmer/wasi
pnpm add @wasmer/wasi
yarn add @wasmer/wasi
bun add @wasmer/wasi
```
## Health
**Score 45/100 (D)** — status: abandoned.
Positive: has types; esm support; no vulnerabilities; high maintenance score; high quality score.
Warnings: low downloads.
Negative: abandoned.
## Facts
| | |
|---|---|
| Version | 1.2.2 |
| Published | 2022-12-01 |
| First published | 2019-09-30 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM + CommonJS |
| Dependencies | 0 |
| Unpacked size | 6.5 MB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 1223 |
| Author | Wasmer Engineering Team |
| Maintainers | michael-f-bryan, syrusakbary |
| Keywords | webassembly, wasm, wasi |
## Links
- npm: https://www.npmjs.com/package/@wasmer/wasi
- Repository: https://github.com/wasmerio/wasmer-js
- Issues: https://github.com/wasmerio/wasmer-js/issues
- npm.io page: https://npm.io/package/@wasmer/wasi
## Recent versions
- 1.2.2 (latest) — 2022-12-01
- 1.2.1 — 2022-12-01
- 1.2.0 — 2022-11-21
- 1.1.2 — 2022-09-01
- 1.1.1 — 2022-08-31
- 1.1.0 — 2022-08-30
- 1.0.2 — 2021-12-14
- 1.0.0 — 2021-12-07
- 0.12.0 — 2020-09-16
- 0.11.2 — 2020-05-14
- 0.11.1 — 2020-05-14
- 0.11.0 — 2020-05-13
- 0.10.2 — 2020-03-18
- 0.10.1 — 2020-03-10
- 0.10.0 — 2020-03-05
- … 29 more at https://npm.io/package/@wasmer/wasi/versions
## README
# 
Wasmer JS [](https://slack.wasmer.io)
This repository consists of multiple packages:
* [Wasmer WASI](#wasmer-wasi)
# Wasmer WASI
Isomorphic Javascript library for interacting with WASI Modules in Node.js, the Browser and [Deno](https://deno.land/x/wasm).
The Javascript Package supports:
* [X] WASI (with command args, envs and stdio)
* [X] In-Memory filesystem (MemFS)
### NPM
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
### Deno
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
### Typescript API
```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](https://webassembly.org/):
> 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](https://webassembly.org/docs/portability/#assumptions-for-efficient-execution)
> available on a wide range of platforms.
About safety:
> WebAssembly describes a memory-safe, sandboxed [execution
> environment](https://webassembly.org/docs/semantics/#linear-memory) […].
# 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
---
_Source: https://npm.io/package/@wasmer/wasi · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._