C to 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/f61eb0d0/2-c-wasm/program.wasm')
    .then(m => {
      window.getSqrt = m.getSqrt;
    });
  </script>

#include <math.h>

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