From 1e35f2b282a20b41000e6b048fa5a16e147d930b Mon Sep 17 00:00:00 2001
From: Clement Hoang <clement.hoang24@gmail.com>
Date: Thu, 2 Nov 2017 15:21:06 -0700
Subject: [PATCH] Put createRoot export under a feature flag (#11426)

---
 .../src/ReactNativeCSFeatureFlags.js            |  1 +
 .../src/__tests__/ReactDOMRoot-test.js          |  1 +
 packages/react-dom/src/client/ReactDOM.js       | 17 +++++++++++------
 packages/shared/ReactFeatureFlags.js            |  3 +++
 4 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/packages/react-cs-renderer/src/ReactNativeCSFeatureFlags.js b/packages/react-cs-renderer/src/ReactNativeCSFeatureFlags.js
index b419fe6b0b..2e76886194 100644
--- a/packages/react-cs-renderer/src/ReactNativeCSFeatureFlags.js
+++ b/packages/react-cs-renderer/src/ReactNativeCSFeatureFlags.js
@@ -13,6 +13,7 @@ var ReactNativeCSFeatureFlags: FeatureFlags = {
   enableAsyncSubtreeAPI: true,
   enableAsyncSchedulingByDefaultInReactDOM: false,
   enableReactFragment: false,
+  enableCreateRoot: false,
   // React Native CS uses persistent reconciler.
   enableMutatingReconciler: false,
   enableNoopReconciler: false,
diff --git a/packages/react-dom/src/__tests__/ReactDOMRoot-test.js b/packages/react-dom/src/__tests__/ReactDOMRoot-test.js
index c4a327b116..7135445196 100644
--- a/packages/react-dom/src/__tests__/ReactDOMRoot-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMRoot-test.js
@@ -9,6 +9,7 @@
 
 'use strict';
 
+require('shared/ReactFeatureFlags').enableCreateRoot = true;
 var React = require('react');
 var ReactDOM = require('react-dom');
 var ReactDOMServer = require('react-dom/server');
diff --git a/packages/react-dom/src/client/ReactDOM.js b/packages/react-dom/src/client/ReactDOM.js
index aced891efa..0c113073d6 100644
--- a/packages/react-dom/src/client/ReactDOM.js
+++ b/packages/react-dom/src/client/ReactDOM.js
@@ -787,12 +787,7 @@ ReactRoot.prototype.unmount = function(callback) {
   DOMRenderer.updateContainer(null, root, null, callback);
 };
 
-var ReactDOM = {
-  createRoot(container: DOMContainer, options?: RootOptions): ReactRootNode {
-    const hydrate = options != null && options.hydrate === true;
-    return new ReactRoot(container, hydrate);
-  },
-
+var ReactDOM: Object = {
   createPortal,
 
   findDOMNode(
@@ -952,6 +947,16 @@ var ReactDOM = {
   },
 };
 
+if (ReactFeatureFlags.enableCreateRoot) {
+  ReactDOM.createRoot = function createRoot(
+    container: DOMContainer,
+    options?: RootOptions,
+  ): ReactRootNode {
+    const hydrate = options != null && options.hydrate === true;
+    return new ReactRoot(container, hydrate);
+  };
+}
+
 const foundDevTools = injectInternals({
   findFiberByHostInstance: ReactDOMComponentTree.getClosestInstanceFromNode,
   findHostInstanceByFiber: DOMRenderer.findHostInstance,
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 8d71dd0a87..b9f2d2a952 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -14,6 +14,7 @@ export type FeatureFlags = {|
   enableNoopReconciler: boolean,
   enablePersistentReconciler: boolean,
   enableReactFragment: boolean,
+  enableCreateRoot: boolean,
 |};
 
 var ReactFeatureFlags: FeatureFlags = {
@@ -27,6 +28,8 @@ var ReactFeatureFlags: FeatureFlags = {
   enablePersistentReconciler: false,
   // Exports React.Fragment
   enableReactFragment: false,
+  // Exports ReactDOM.createRoot
+  enableCreateRoot: false,
 };
 
 if (__DEV__) {