Function hydrateRoot

packages/react-dom/src/client/ReactDOMRoot.js:274–358

(
  container: Document | Element,
  initialChildren: ReactNodeList,
  options?: HydrateRootOptions,
)

ReactDOMHydrationRoot.prototype.unstable_scheduleHydration = scheduleHydration;

export function hydrateRoot(
  container: Document | Element,
  initialChildren: ReactNodeList,
  options?: HydrateRootOptions,
): RootType {
  if (!isValidContainer(container)) {
    throw new Error('Target container is not a DOM element.');
  }

  warnIfReactDOMContainerInDEV(container);

  if (__DEV__) {
    if (initialChildren === undefined) {
      console.error(
        'Must provide initial children as second argument to hydrateRoot. ' +
          'Example usage: hydrateRoot(domContainer, <App />)',
      );
    }
  }

  // For now we reuse the whole bag of options since they contain
  // the hydration callbacks.
  const hydrationCallbacks = options != null ? options : null;

  const concurrentUpdatesByDefaultOverride = false;
  let isStrictMode = false;
  let identifierPrefix = '';
  let onUncaughtError = defaultOnUncaughtError;
  let onCaughtError = defaultOnCaughtError;
  let onRecoverableError = defaultOnRecoverableError;
  let onDefaultTransitionIndicator = defaultOnDefaultTransitionIndicator;
  let transitionCallbacks = null;
  let formState = null;
  if (options !== null && options !== undefined) {
    if (options.unstable_strictMode === true) {
      isStrictMode = true;
    }
    if (options.identifierPrefix !== undefined) {
      identifierPrefix = options.identifierPrefix;
    }
    if (options.onUncaughtError !== undefined) {
      onUncaughtError = options.onUncaughtError;
    }
    if (options.onCaughtError !== undefined) {
      onCaughtError = options.onCaughtError;
    }
    if (options.onRecoverableError !== undefined) {
      onRecoverableError = options.onRecoverableError;
    }
    if (enableDefaultTransitionIndicator) {
      if (options.onDefaultTransitionIndicator !== undefined) {
        onDefaultTransitionIndicator = options.onDefaultTransitionIndicator;
      }
    }
    if (options.unstable_transitionCallbacks !== undefined) {
      transitionCallbacks = options.unstable_transitionCallbacks;
    }
    if (options.formState !== undefined) {