Function legacyCreateRootFromDOMContainer

code/styling/public/app.js:17798–17823

(container, forceHydrate)

var warnedAboutHydrateAPI = false;

function legacyCreateRootFromDOMContainer(container, forceHydrate) {
  var shouldHydrate = forceHydrate || shouldHydrateDueToLegacyHeuristic(container);
  // First clear any existing content.
  if (!shouldHydrate) {
    var warned = false;
    var rootSibling = void 0;
    while (rootSibling = container.lastChild) {
      {
        if (!warned && rootSibling.nodeType === ELEMENT_NODE && rootSibling.hasAttribute(ROOT_ATTRIBUTE_NAME)) {
          warned = true;
          warning(false, 'render(): Target node has markup rendered by React, but there ' + 'are unrelated nodes as well. This is most commonly caused by ' + 'white-space inserted around server-rendered markup.');
        }
      }
      container.removeChild(rootSibling);
    }
  }
  {
    if (shouldHydrate && !forceHydrate && !warnedAboutHydrateAPI) {
      warnedAboutHydrateAPI = true;
      lowPriorityWarning$1(false, 'render(): Calling ReactDOM.render() to hydrate server-rendered markup ' + 'will stop working in React v17. Replace the ReactDOM.render() call ' + 'with ReactDOM.hydrate() if you want React to attach to the server HTML.');
    }
  }
  // Legacy roots are not async by default.
  var isAsync = false;
  return new ReactRoot(container, isAsync, shouldHydrate);
}

function legacyRenderSubtreeIntoContainer(parentComponent, children, container, forceHydrate, callback) {
  // TODO: Ensure all entry points contain this check