example/dist/bundle.js
function createFiberRoot(containerInfo, isAsync, hydrate) {
  // Cyclic construction. This cheats the type system right now because
  // stateNode is any.
  var uninitializedFiber = createHostRootFiber(isAsync);

  var root = void 0;
  if (enableSchedulerTracing) {
    root = {
      current: uninitializedFiber,
      containerInfo: containerInfo,
      pendingChildren: null,

      earliestPendingTime: NoWork,
      latestPendingTime: NoWork,
      earliestSuspendedTime: NoWork,
      latestSuspendedTime: NoWork,
      latestPingedTime: NoWork,

      didError: false,

      pendingCommitExpirationTime: NoWork,
      finishedWork: null,
      timeoutHandle: noTimeout,
      context: null,
      pendingContext: null,
      hydrate: hydrate,
      nextExpirationTimeToWorkOn: NoWork,
      expirationTime: NoWork,
      firstBatch: null,
      nextScheduledRoot: null,

      interactionThreadID: tracing.unstable_getThreadID(),
      memoizedInteractions: new Set(),
      pendingInteractionMap: new Map()
    };
  } else {
    root = {
      current: uninitializedFiber,
      containerInfo: containerInfo,
      pendingChildren: null,

      earliestPendingTime: NoWork,
      latestPendingTime: NoWork,
      earliestSuspendedTime: NoWork,
      latestSuspendedTime: NoWork,
      latestPingedTime: NoWork,

      didError: false,

      pendingCommitExpirationTime: NoWork,
      finishedWork: null,
      timeoutHandle: noTimeout,
      context: null,
      pendingContext: null,
      hydrate: hydrate,
      nextExpirationTimeToWorkOn: NoWork,
      expirationTime: NoWork,
      firstBatch: null,
      nextScheduledRoot: null
    };
  }

  uninitializedFiber.stateNode = root;

  // The reason for the way the Flow types are structured in this file,
  // Is to avoid needing :any casts everywhere interaction tracing fields are used.
  // Unfortunately that requires an :any cast for non-interaction tracing capable builds.
  // $FlowFixMe Remove this :any cast and replace it with something better.
  return root;
}
function createFiberRoot(containerInfo, isAsync, hydrate) {
  // Cyclic construction. This cheats the type system right now because
  // stateNode is any.
  var uninitializedFiber = createHostRootFiber(isAsync);

  var root = void 0;
  if (enableSchedulerTracing) {
    root = {
      current: uninitializedFiber,
      containerInfo: containerInfo,
      pendingChildren: null,

      earliestPendingTime: NoWork,
      latestPendingTime: NoWork,
      earliestSuspendedTime: NoWork,
      latestSuspendedTime: NoWork,
      latestPingedTime: NoWork,

      didError: false,

      pendingCommitExpirationTime: NoWork,
      finishedWork: null,
      timeoutHandle: noTimeout,
      context: null,
      pendingContext: null,
      hydrate: hydrate,
      nextExpirationTimeToWorkOn: NoWork,
      expirationTime: NoWork,
      firstBatch: null,
      nextScheduledRoot: null,

      interactionThreadID: tracing.unstable_getThreadID(),
      memoizedInteractions: new Set(),
      pendingInteractionMap: new Map()
    };
  } else {
    root = {
      current: uninitializedFiber,
      containerInfo: containerInfo,
      pendingChildren: null,

      earliestPendingTime: NoWork,
      latestPendingTime: NoWork,
      earliestSuspendedTime: NoWork,
      latestSuspendedTime: NoWork,
      latestPingedTime: NoWork,

      didError: false,

      pendingCommitExpirationTime: NoWork,
      finishedWork: null,
      timeoutHandle: noTimeout,
      context: null,
      pendingContext: null,
      hydrate: hydrate,
      nextExpirationTimeToWorkOn: NoWork,
      expirationTime: NoWork,
      firstBatch: null,
      nextScheduledRoot: null
    };
  }

  uninitializedFiber.stateNode = root;

  // The reason for the way the Flow types are structured in this file,
  // Is to avoid needing :any casts everywhere interaction tracing fields are used.
  // Unfortunately that requires an :any cast for non-interaction tracing capable builds.
  // $FlowFixMe Remove this :any cast and replace it with something better.
  return root;
}
Exported FiberRoot type includes all properties, To avoid requiring potentially error-prone :any casts throughout the project. Profiling properties are only safe to access in profiling builds (when enableSchedulerTracing is true). The types are defined separately within this file to ensure they stay in sync. (We don't have to use an inline :any cast when enableSchedulerTracing is disabled.) /* eslint-enable no-use-before-define