判定是否是有效的容器

import { disableCommentsAsDOMContainers } from 'shared/ReactFeatureFlags';

import {
  ELEMENT_NODE,
  COMMENT_NODE,
  DOCUMENT_NODE,
  DOCUMENT_FRAGMENT_NODE,
} from './HTMLNodeType';

export function isValidContainer(node: any): boolean {
  return !!(
    node &&
    (node.nodeType === ELEMENT_NODE ||
      node.nodeType === DOCUMENT_NODE ||
      node.nodeType === DOCUMENT_FRAGMENT_NODE ||
      (!disableCommentsAsDOMContainers &&
        node.nodeType === COMMENT_NODE &&
        (node as any).nodeValue === ' react-mount-point-unstable '))
  );
}