Function createFiberRoot

packages/react-reconciler/src/ReactFiberRoot.js:158–237

(
  containerInfo: Container,
  tag: RootTag,
  hydrate: boolean,
  initialChildren: ReactNodeList,
  hydrationCallbacks: null | SuspenseHydrationCallbacks,
  isStrictMode: boolean,
  // TODO: We have several of these arguments that are conceptually part of the
  // host config, but because they are passed in at runtime, we have to thread
  // them through the root constructor. Perhaps we should put them all into a
  // single type, like a DynamicHostConfig that is defined by the renderer.
  identifierPrefix: string,
  formState: ReactFormState<any, any> | null,
  onUncaughtError: (
    error: mixed,
    errorInfo: {+componentStack?: ?string},
  ) => void,
  onCaughtError: (
    error: mixed,
    errorInfo: {
      +componentStack?: ?string,
      +errorBoundary?: ?component(...props: any),
    },
  ) => void,
  onRecoverableError: (
    error: mixed,
    errorInfo: {+componentStack?: ?string},
  ) => void,
  onDefaultTransitionIndicator: () => void | (() => void),
  transitionCallbacks: null | TransitionTracingCallbacks,
)

}

export function createFiberRoot(
  containerInfo: Container,
  tag: RootTag,
  hydrate: boolean,
  initialChildren: ReactNodeList,
  hydrationCallbacks: null | SuspenseHydrationCallbacks,
  isStrictMode: boolean,
  // TODO: We have several of these arguments that are conceptually part of the
  // host config, but because they are passed in at runtime, we have to thread
  // them through the root constructor. Perhaps we should put them all into a
  // single type, like a DynamicHostConfig that is defined by the renderer.
  identifierPrefix: string,
  formState: ReactFormState<any, any> | null,
  onUncaughtError: (
    error: mixed,
    errorInfo: {+componentStack?: ?string},
  ) => void,
  onCaughtError: (
    error: mixed,
    errorInfo: {
      +componentStack?: ?string,
      +errorBoundary?: ?component(...props: any),
    },
  ) => void,
  onRecoverableError: (
    error: mixed,
    errorInfo: {+componentStack?: ?string},
  ) => void,
  onDefaultTransitionIndicator: () => void | (() => void),
  transitionCallbacks: null | TransitionTracingCallbacks,
): FiberRoot {
  // $FlowFixMe[invalid-constructor] Flow no longer supports calling new on functions
  const root: FiberRoot = (new FiberRootNode(
    containerInfo,
    tag,
    hydrate,
    identifierPrefix,
    onUncaughtError,
    onCaughtError,
    onRecoverableError,
    onDefaultTransitionIndicator,
    formState,
  ): any);
  if (enableSuspenseCallback) {
    root.hydrationCallbacks = hydrationCallbacks;
  }

  if (enableTransitionTracing) {
    root.transitionCallbacks = transitionCallbacks;
  }

  // Cyclic construction. This cheats the type system right now because
  // stateNode is any.
  const uninitializedFiber = createHostRootFiber(tag, isStrictMode);
  root.current = uninitializedFiber;
  uninitializedFiber.stateNode = root;

  const initialCache = createCache();