ar-navigation/js/camera-select.js

const video = document.getElementById('arjs-video');
const button = document.getElementById('button');
const select = document.getElementById('select');
let currentStream;

function stopMediaTracks(stream) {
  stream.getTracks().forEach(track => {
    track.stop();
  });
}

function gotDevices(mediaDevices) {
  select.innerHTML = '';
  select.appendChild(document.createElement('option'));
  let count = 1;
  mediaDevices.forEach(mediaDevice => {
    if (mediaDevice.kind === 'videoinput') {
      const option = document.createElement('option');
      option.value = mediaDevice.deviceId;
      const label = mediaDevice.label || `Camera ${count++}`;
      const textNode = document.createTextNode(label);
      option.appendChild(textNode);
      select.appendChild(option);
    }
  });
}

button.addEventListener('click', event => {
  if (typeof currentStream !== 'undefined') {
    stopMediaTracks(currentStream);
  }
  const videoConstraints = {};
  if (select.value === '') {
    videoConstraints.facingMode = 'environment';
  } else {
    videoConstraints.deviceId = { exact: select.value };
  }
  const constraints = {
    video: videoConstraints,
    audio: false
  };

  // navigator.mediaDevices
  //   .getUserMedia(constraints)
  //   .then(stream => {
  //     currentStream = stream;
  //     video.srcObject = stream;
  //     return navigator.mediaDevices.enumerateDevices();
  //   })
  //   .then(gotDevices)
  //   .catch(error => {
  //     console.error(error);
  //   });
  navigator.mediaDevices
    .getUserMedia(constraints)
    .then((stream) => {
      currentStream = stream;

      document.getElementById('arjs-video').srcObject = stream;
      var event = new CustomEvent("camera-init", { stream: stream });
      window.dispatchEvent(event);

      document.body.addEventListener("click", function () {
          document.getElementById('arjs-video').play();
        });
      return navigator.mediaDevices.enumerateDevices();
    })
    .then(gotDevices)
    .catch((error) => {
      console.error(error);
    });

});

navigator.mediaDevices.enumerateDevices().then(gotDevices);