WebAssembly on Node.js

index.js

const { readFileSync } = require("fs");

async function instantiate(source, config) {
  const compiled = await WebAssembly.compile(source);
  return new WebAssembly.Instance(compiled, config);
}

const config = {
  env: {
    __memory_base: 0,
    __table_base: 0,
    memory: new WebAssembly.Memory({
      initial: 256,
      maximum: 256
    }),
    table: new WebAssembly.Table({
      initial: 0,
      element: "anyfunc"
    })
  }
};

async function main() {
  const source = readFileSync("./test.wasm");
  const instance = await instantiate(source, config);
  console.log(instance.exports._add(9, 9));
  console.log(instance.exports._add(9, 19));
  console.log(instance.exports._add(9, 29));
  console.log(instance.exports._add(9, 39));
}

main();

Makefile

build:
	emcc test.c -O3 -s WASM=1 -s EXPORTED_FUNCTIONS='["_add"]' -s SIDE_MODULE=1 -o test.wasm
run:
	node index.js

test.c

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