Detect User Media Devices and Permission (Async/Await)

user_media_detector.js

class UserMediaDetector {

  // Returns info on all user media devices.
  async devices() {
    if (!navigator.mediaDevices || !navigator.mediaDevices.enumerateDevices) {
      throw(Error("UserMediaDetector getDevices failed: enumerateDevices is not supported"));
    }

    const mediaDevices = await navigator.mediaDevices.enumerateDevices();

    return mediaDevices.map(
      ({ deviceId, groupId, kind, label }) => ({ deviceId, groupId, kind, label })
    );
  }

  // Returns permitted status of given user media.
  async permitted(kind) {
    if (!kind || !Object.values(UserMediaDetector.Kinds).includes(kind)) {
      throw(Error(`UserMediaDetector permitted failed: kind ${kind} is not supported`));
    }

    const devices = await this.devices();

    // Note: The presence of a `label` on a device indicates that it
    //   the device is active or persistent permissions are granted.
    const permitted = !!devices.find(
      device => device.kind === kind && !!device.label
    );

    return permitted;
  }

  // Returns boolean value designating if all given media kinds are permitted.
  async permittedAll(kinds = Object.values(UserMediaDetector.Kinds)) {
    const kindsArray = Array.isArray(kinds) ? kinds : Array.of(kinds);
    const permissionStates = await Promise.all(kindsArray.map(kind => this.permitted(kind)));

    return permissionStates.every(isPermitted => isPermitted);
  }
}

UserMediaDetector.Kinds = {
  VideoInput: "videoinput",
  AudioInput: "audioinput",
  AudioOutput: "audioinput"
};

export default UserMediaDetector;

Example usage:

const detector = new UserMediaDetector();
const weHaveCameraPermission = await detector.permitted(UserMediaDetector.Kinds.VideoInput);
console.log(weHaveCameraPermission);