fibonacci-wasm.js

let x = '../out/main.wasm';

let instance = null;

fetch(x).then(response =>
  response.arrayBuffer()
).then(bytes =>
  WebAssembly.instantiate(bytes, {
    env: {
      add_js: (a, b) => a + b
    }
  })
).then(results => {
  instance = results.instance;

  const arr = [];
  const start = performance.now();
  for (var i = 0; i < 1000000; i++) {
    arr.push(instance.exports.fibonacci_wasm(45));
  }

  document.getElementById("container").innerText = arr[ arr.length - 1 ] + ":" + ( performance.now() - start );
}).catch(console.error);