code: function (cameraEl) {
      var cameraData;
      var sceneEl = this.el.sceneEl;
      this.numUserCamerasChecked++;
  
      // Already found one.
      if (this.initialCameraFound) { return; }
  
      // Check if camera is appropriate for being the initial camera.
      cameraData = cameraEl.getAttribute('camera');
      if (!cameraData.active || cameraData.spectator) {
        // No user cameras eligible, create default camera.
        if (this.numUserCamerasChecked === this.numUserCameras) {
          this.createDefaultCamera();
        }
        return;
      }
  
      this.initialCameraFound = true;
      sceneEl.camera = cameraEl.getObject3D('camera');
      sceneEl.emit('cameraready', {cameraEl: cameraEl});
    }
docs: Check if a user-defined camera entity is appropriate to be initial camera.
  (active + non-spectator).
  
  Keep track of the number of cameras we checked and whether we found one.