Function isFiberMounted

docs/external/js/react-dom.development.js:3040–3042

(fiber)

    return fiber.tag === HostRoot ? fiber.stateNode.containerInfo : null;
  }
  function isFiberMounted(fiber) {
    return getNearestMountedFiber(fiber) === fiber;
  }
  function isMounted(component) {
    {
      var owner = ReactCurrentOwner.current;