function anchorsSupported(sceneEl) {
  var xrManager = sceneEl.renderer.xr;
  var session = xrManager.getSession();
  return session && session.restorePersistentAnchor;
}
Anchored component.
Feature only available in browsers that implement the WebXR anchors module.
Once anchored the entity remains to a fixed position in real-world space.
If the anchor is persistent, the anchor positioned remains across sessions or until the browser data is cleared.