WebAssembly compile and run example

wasm.js

/* global WebAssembly */
import wast2wasm from 'wast2wasm';

// Run with: babel-node --expose-wasm ./wasm.js

const wast = `(module
  (func $fac (param i32) (result i32)
    get_local 0
    i32.eqz
    if i32
      i32.const 1
    else
      get_local 0
      get_local 0
      i32.const 1
      i32.sub
      call 0
      i32.mul
    end
  )
  (export "main" (func $fac))
)`;

const wasmImports = {};

const compile = async (source) => {
  const result = await wast2wasm(source);
  const wasm = new Buffer(result.buffer);
  console.log(`0x${wasm.toString('hex')}`);
  console.log(wasm.toString('ascii'));
  const module = new WebAssembly.Module(wasm);
  const instance = new WebAssembly.Instance(module, wasmImports);
  return instance.exports;
};                                                                                                                                                             
                                                                                                                                                               
const asyncMain = async () => {                                                                                                                                
  const { main } = await compile(wast);                                                                                                                        
  for (let i = 0; i < 30; ++i) {                                                                                                                               
    console.log(i, main(i));                                                                                                                                   
  }
};

asyncMain();