My WASI runtime wrapper template in Node.js (v20+)

run.mjs

import { readFile } from 'node:fs/promises'
import { WASI } from 'wasi'
import { argv, env } from 'node:process'
import * as path from 'node:path'

const wasmPath = path.resolve('/path/to/wasm/here.wasm')

const args = [path.basename(wasmPath), ...argv.slice(2)]

const wasi = new WASI({
  version: 'preview1',
  args,
  env,
  preopens: {
    '/': '/',
  },
  returnOnExit: true,
})

console.log('Compiling...', wasmPath, args)
const wasm = await WebAssembly.compile(
  await readFile(wasmPath),
)

const importObject = wasi.getImportObject()
if (importObject.wasi_unstable) {
  importObject.wasi_snapshot_preview1 = importObject.wasi_unstable
}

console.log('Instantiating...')
const instance = await WebAssembly.instantiate(wasm, importObject)

console.log('Starting...')
const ret = wasi.start(instance)

console.log('Exited with code', ret)
process.exit(ret)