ReactDOM.useEvent: add support for beforeblur/afterblur (#18370)

* ReactDOM.useEvent: add support for beforeblur/afterblur

package.json

@@ -113,6 +113,7 @@
     "test-persistent": "cross-env NODE_ENV=development jest --config ./scripts/jest/config.source-persistent.js",
     "debug-test-persistent": "cross-env NODE_ENV=development node --inspect-brk node_modules/jest/bin/jest.js --config ./scripts/jest/config.source-persistent.js --runInBand",
     "test-prod": "cross-env NODE_ENV=production jest --config ./scripts/jest/config.source.js",
+    "debug-test-prod": "cross-env NODE_ENV=production node --inspect-brk node_modules/jest/bin/jest.js --config ./scripts/jest/config.source.js --runInBand",
     "test-prod-build": "yarn test-build-prod",
     "test-build": "cross-env NODE_ENV=development jest --config ./scripts/jest/config.build.js",
     "test-build-prod": "cross-env NODE_ENV=production jest --config ./scripts/jest/config.build.js",

packages/react-dom/src/client/ReactDOMHostConfig.js

@@ -7,6 +7,7 @@
  * @flow
  */
 
+import type {TopLevelType} from 'legacy-events/TopLevelEventTypes';
 import type {RootType} from './ReactDOMRoot';
 
 import {
@@ -84,6 +85,7 @@ import {
   attachTargetEventListener,
 } from '../events/DOMModernPluginEventSystem';
 import {getListenerMapForElement} from '../events/DOMEventListenerMap';
+import {TOP_BEFORE_BLUR, TOP_AFTER_BLUR} from '../events/DOMTopLevelEventTypes';
 
 export type ReactListenerEvent = ReactDOMListenerEvent;
 export type ReactListenerMap = ReactDOMListenerMap;
@@ -238,11 +240,11 @@ export function resetAfterCommit(containerInfo: Container): void {
   restoreSelection(selectionInformation);
   ReactBrowserEventEmitterSetEnabled(eventsEnabled);
   eventsEnabled = null;
-  if (enableDeprecatedFlareAPI) {
+  if (enableDeprecatedFlareAPI || enableUseEventAPI) {
     const activeElementDetached = (selectionInformation: any)
       .activeElementDetached;
     if (activeElementDetached !== null) {
-      dispatchDetachedBlur(activeElementDetached);
+      dispatchAfterDetachedBlur(activeElementDetached);
     }
   }
   selectionInformation = null;
@@ -490,34 +492,66 @@ export function insertInContainerBefore(
   }
 }
 
+function createEvent(type: TopLevelType): Event {
+  const event = document.createEvent('Event');
+  event.initEvent(((type: any): string), false, false);
+  return event;
+}
+
 function dispatchBeforeDetachedBlur(target: HTMLElement): void {
   const targetInstance = getClosestInstanceFromNode(target);
   ((selectionInformation: any): SelectionInformation).activeElementDetached = target;
 
-  DEPRECATED_dispatchEventForResponderEventSystem(
-    'beforeblur',
-    targetInstance,
-    ({
+  if (enableDeprecatedFlareAPI) {
+    DEPRECATED_dispatchEventForResponderEventSystem(
+      'beforeblur',
+      targetInstance,
+      ({
+        target,
+        timeStamp: Date.now(),
+      }: any),
       target,
-      timeStamp: Date.now(),
-    }: any),
-    target,
-    RESPONDER_EVENT_SYSTEM | IS_PASSIVE,
-  );
+      RESPONDER_EVENT_SYSTEM | IS_PASSIVE,
+    );
+  }
+  if (enableUseEventAPI) {
+    try {
+      // We need to temporarily enable the event system
+      // to dispatch the "beforeblur" event.
+      ReactBrowserEventEmitterSetEnabled(true);
+      const event = createEvent(TOP_BEFORE_BLUR);
+      // Dispatch "beforeblur" directly on the target,
+      // so it gets picked up by the event system and
+      // can propagate through the React internal tree.
+      target.dispatchEvent(event);
+    } finally {
+      ReactBrowserEventEmitterSetEnabled(false);
+    }
+  }
 }
 
-function dispatchDetachedBlur(target: HTMLElement): void {
-  DEPRECATED_dispatchEventForResponderEventSystem(
-    'blur',
-    null,
-    ({
-      isTargetAttached: false,
+function dispatchAfterDetachedBlur(target: HTMLElement): void {
+  if (enableDeprecatedFlareAPI) {
+    DEPRECATED_dispatchEventForResponderEventSystem(
+      'blur',
+      null,
+      ({
+        isTargetAttached: false,
+        target,
+        timeStamp: Date.now(),
+      }: any),
       target,
-      timeStamp: Date.now(),
-    }: any),
-    target,
-    RESPONDER_EVENT_SYSTEM | IS_PASSIVE,
-  );
+      RESPONDER_EVENT_SYSTEM | IS_PASSIVE,
+    );
+  }
+  if (enableUseEventAPI) {
+    const event = createEvent(TOP_AFTER_BLUR);
+    // So we know what was detached, make the relatedTarget the
+    // detached target on the "afterblur" event.
+    (event: any).relatedTarget = target;
+    // Dispatch the event on the document.
+    document.dispatchEvent(event);
+  }
 }
 
 // This is a specific event for the React Flare
@@ -528,7 +562,7 @@ export function beforeRemoveInstance(
   instance: Instance | TextInstance | SuspenseInstance,
 ): void {
   if (
-    enableDeprecatedFlareAPI &&
+    (enableDeprecatedFlareAPI || enableUseEventAPI) &&
     selectionInformation &&
     instance === selectionInformation.focusedElem
   ) {
@@ -639,7 +673,7 @@ export function hideInstance(instance: Instance): void {
   // is ether the instance of a child or the instance. We need
   // to traverse the Fiber tree here rather than use node.contains()
   // as the child node might be inside a Portal.
-  if (enableDeprecatedFlareAPI && selectionInformation) {
+  if ((enableDeprecatedFlareAPI || enableUseEventAPI) && selectionInformation) {
     const focusedElem = selectionInformation.focusedElem;
     if (focusedElem !== null && instanceContainsElem(instance, focusedElem)) {
       dispatchBeforeDetachedBlur(((focusedElem: any): HTMLElement));

packages/react-dom/src/events/DOMEventProperties.js

@@ -23,6 +23,7 @@ import {
   UserBlockingEvent,
   ContinuousEvent,
 } from 'shared/ReactTypes';
+import {enableUseEventAPI} from 'shared/ReactFeatureFlags';
 
 // Needed for SimpleEventPlugin, rather than
 // do it in two places, which duplicates logic
@@ -95,6 +96,13 @@ const otherDiscreteEvents = [
   DOMTopLevelEventTypes.TOP_COMPOSITION_UPDATE,
 ];
 
+if (enableUseEventAPI) {
+  otherDiscreteEvents.push(
+    DOMTopLevelEventTypes.TOP_BEFORE_BLUR,
+    DOMTopLevelEventTypes.TOP_AFTER_BLUR,
+  );
+}
+
 // prettier-ignore
 const userBlockingPairsForSimpleEventPlugin = [
   DOMTopLevelEventTypes.TOP_DRAG, 'drag',

packages/react-dom/src/events/DOMModernPluginEventSystem.js

@@ -75,6 +75,8 @@ import {
   TOP_PROGRESS,
   TOP_PLAYING,
   TOP_CLICK,
+  TOP_BEFORE_BLUR,
+  TOP_AFTER_BLUR,
 } from './DOMTopLevelEventTypes';
 import {
   getClosestInstanceFromNode,
@@ -84,7 +86,10 @@ import {
 import {COMMENT_NODE} from '../shared/HTMLNodeType';
 import {topLevelEventsToDispatchConfig} from './DOMEventProperties';
 
-import {enableLegacyFBSupport} from 'shared/ReactFeatureFlags';
+import {
+  enableLegacyFBSupport,
+  enableUseEventAPI,
+} from 'shared/ReactFeatureFlags';
 
 const capturePhaseEvents = new Set([
   TOP_FOCUS,
@@ -122,6 +127,11 @@ const capturePhaseEvents = new Set([
   TOP_WAITING,
 ]);
 
+if (enableUseEventAPI) {
+  capturePhaseEvents.add(TOP_BEFORE_BLUR);
+  capturePhaseEvents.add(TOP_AFTER_BLUR);
+}
+
 const emptyDispatchConfigForCustomEvents: CustomDispatchConfig = {
   customEvent: true,
   phasedRegistrationNames: {

packages/react-dom/src/events/DOMTopLevelEventTypes.js

@@ -149,6 +149,9 @@ export const TOP_VOLUME_CHANGE = unsafeCastStringToDOMTopLevelType(
 export const TOP_WAITING = unsafeCastStringToDOMTopLevelType('waiting');
 export const TOP_WHEEL = unsafeCastStringToDOMTopLevelType('wheel');
 
+export const TOP_AFTER_BLUR = unsafeCastStringToDOMTopLevelType('afterblur');
+export const TOP_BEFORE_BLUR = unsafeCastStringToDOMTopLevelType('beforeblur');
+
 // List of events that need to be individually attached to media elements.
 // Note that events in this list will *not* be listened to at the top level
 // unless they're explicitly whitelisted in `ReactBrowserEventEmitter.listenTo`.

packages/react-dom/src/events/SimpleEventPlugin.js

@@ -105,6 +105,8 @@ const SimpleEventPlugin: PluginModule<MouseEvent> = {
         break;
       case DOMTopLevelEventTypes.TOP_BLUR:
       case DOMTopLevelEventTypes.TOP_FOCUS:
+      case DOMTopLevelEventTypes.TOP_BEFORE_BLUR:
+      case DOMTopLevelEventTypes.TOP_AFTER_BLUR:
         EventConstructor = SyntheticFocusEvent;
         break;
       case DOMTopLevelEventTypes.TOP_CLICK: