How to use WebAssembly from node.js?

Question

I am currently working on a personal Node.js (>=8.0.0) project which requires me to call C subroutines (to improve execution time). I am trying to use WebAssembly to do this

Answer 1

Thanks @sven. ( translate only )

test.c:

#include 

int EMSCRIPTEN_KEEPALIVE add(int a, int b) {
    return a + b;
}

compiling:

emcc test.c -O2 -s WASM=1 -s SIDE_MODULE=1 -o test.wasm

test.js:

const util = require('util');
const fs = require('fs');
var source = fs.readFileSync('./test.wasm');
const env = {
  __memory_base: 0,
  tableBase: 0,
  memory: new WebAssembly.Memory({
    initial: 256
  }),
  table: new WebAssembly.Table({
    initial: 0,
    element: 'anyfunc'
  })
}

var typedArray = new Uint8Array(source);

WebAssembly.instantiate(typedArray, {
  env: env
}).then(result => {
  console.log(util.inspect(result, true, 0));
  console.log(result.instance.exports._add(10, 9));
}).catch(e => {
  // error caught
  console.log(e);
});