gum_query.html

<html>
<meta charset=utf-8>
<video id="video" width="320" height="240" autoplay muted></video><br>
<button id="button">Go!</button>
<div id="div"></div>
<script>
const console = {log: msg => div.innerHTML += `${msg}<br>`};
const wait = ms => new Promise(r => setTimeout(r, ms));

(async () => {
  try {
    await dumpState("Before: ");
  } catch(e) {
    console.log(e);
  }
})();

button.onclick = async () => {
  try {
    const stream = await navigator.mediaDevices.getUserMedia({video: true, audio: true});
    video.srcObject = stream;
    await dumpState("After: ");
  } catch(e) {
    console.log(e);
  }
};

async function dumpState(header = "") {
  const [cam, mic] = await Promise.all([
    navigator.permissions.query({name: "camera"}),
    navigator.permissions.query({name: "microphone"})
  ]);
  console.log(`${header}camera = "${cam.state}", microphone = "${mic.state}"`)
}

</script>
</html>