<!DOCTYPE html>
<meta charset="utf8">
<script>
window.onload = async () => {
  parent.postMessage("ready", "*");
}

window.addEventListener("message", async function listener(event) {
  if (event.data[0] == "gimme") {
    var s = `<html><script>
      let result = {
        hardwareConcurrency : navigator.hardwareConcurrency
      };
      window.parent.document.querySelector('#result').textContent = JSON.stringify(result);
      window.parent.postMessage(["frame_response"], "*");`;
    // eslint-disable-next-line
    s += `</` + `script></html>`;

  	var iframe = document.createElement("iframe");
    iframe.srcdoc = s;
    document.body.append(iframe);

  } else if (event.data[0] == "frame_response") {
    let result = document.querySelector("#result").textContent;
    parent.postMessage(JSON.parse(result), "*");
  }
});
</script>
<output id="result"></output>
