JS from WASM

<!doctype html>
  <title>WASM Test</title>
  <script>
    function fetchAndInstantiateWasm (url, imports) {
      return fetch(url)
      .then(res => {
        if (res.ok)
          return res.arrayBuffer();
        throw new Error(`Unable to fetch Web Assembly file ${url}.`);
      })
      .then(bytes => WebAssembly.compile(bytes))
      .then(module => WebAssembly.instantiate(module, imports || {}))
      .then(instance => instance.exports);
    }

    fetchAndInstantiateWasm('https://cdn.rawgit.com/guybedford/wasm-intro/f61eb0d0/3-calling-js-from-wasm/program.wasm', {
      env: {
        consoleLog: num => console.log(num)
      }
    })
    .then(m => {
      console.log(m.getSqrt(5));
    });
  </script>

#include <math.h>

void consoleLog (float num);

float getSqrt (float num) {
  consoleLog(num);
  return sqrt(num);
}