Modern Event System: refactor legacy FB support logic (#18336)

Author: trueadm

packages/legacy-events/EventSystemFlags.js

@@ -16,3 +16,4 @@ export const IS_ACTIVE = 1 << 3;
 export const PASSIVE_NOT_SUPPORTED = 1 << 4;
 export const IS_REPLAYED = 1 << 5;
 export const IS_FIRST_ANCESTOR = 1 << 6;
+export const LEGACY_FB_SUPPORT = 1 << 7;

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

@@ -1365,7 +1365,6 @@ export function listenToEventResponderEventTypes(
               (targetEventType: any),
               true,
               passiveItem.listener,
-              true,
             );
             listenerMap.delete(passiveKey);
           }

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

@@ -24,6 +24,7 @@ import {registrationNameDependencies} from 'legacy-events/EventPluginRegistry';
 import {batchedEventUpdates} from 'legacy-events/ReactGenericBatching';
 import {executeDispatchesInOrder} from 'legacy-events/EventPluginUtils';
 import {plugins} from 'legacy-events/EventPluginRegistry';
+import {LEGACY_FB_SUPPORT, IS_REPLAYED} from 'legacy-events/EventSystemFlags';
 
 import {HostRoot, HostPortal} from 'shared/ReactWorkTags';
 
@@ -66,6 +67,7 @@ import {
   TOP_RATE_CHANGE,
   TOP_PROGRESS,
   TOP_PLAYING,
+  TOP_CLICK,
 } from './DOMTopLevelEventTypes';
 import {
   getClosestInstanceFromNode,
@@ -78,7 +80,7 @@ import {
   ELEMENT_NODE,
 } from '../shared/HTMLNodeType';
 
-import {enableLegacyFBPrimerSupport} from 'shared/ReactFeatureFlags';
+import {enableLegacyFBSupport} from 'shared/ReactFeatureFlags';
 
 const capturePhaseEvents = new Set([
   TOP_FOCUS,
@@ -197,7 +199,6 @@ export function listenToTopLevelEvent(
         topLevelType,
         isCapturePhase,
         ((listenerEntry: any): ElementListenerMapEntry).listener,
-        ((listenerEntry: any): ElementListenerMapEntry).passive,
       );
     }
     const listener = addTrappedEventListener(
@@ -225,42 +226,24 @@ export function listenToEvent(
   }
 }
 
-const validFBLegacyPrimerRels = new Set([
-  'dialog',
-  'dialog-post',
-  'async',
-  'async-post',
-  'theater',
-  'toggle',
-]);
-
-function willDeferLaterForFBLegacyPrimer(nativeEvent: any): boolean {
-  let node = nativeEvent.target;
-  const type = nativeEvent.type;
-  if (type !== 'click') {
+function willDeferLaterForLegacyFBSupport(
+  topLevelType: DOMTopLevelEventType,
+  targetContainer: EventTarget,
+): boolean {
+  if (topLevelType !== TOP_CLICK) {
     return false;
   }
-  while (node !== null) {
-    // Primer works by intercepting a click event on an <a> element
-    // that has a "rel" attribute that matches one of the valid ones
-    // in the Set above. If we intercept this before Primer does, we
-    // will need to defer the current event till later and discontinue
-    // execution of the current event. To do this we can add a document
-    // event listener and continue again later after propagation.
-    if (node.tagName === 'A' && validFBLegacyPrimerRels.has(node.rel)) {
-      const legacyFBSupport = true;
-      const isCapture = nativeEvent.eventPhase === 1;
-      addTrappedEventListener(
-        null,
-        ((type: any): DOMTopLevelEventType),
-        isCapture,
-        legacyFBSupport,
-      );
-      return true;
-    }
-    node = node.parentNode;
-  }
-  return false;
+  // We defer all click events with legacy FB support mode on.
+  // This means we add a one time event listener to trigger
+  // after the FB delegated listeners fire.
+  const isDeferredListenerForLegacyFBSupport = true;
+  addTrappedEventListener(
+    targetContainer,
+    topLevelType,
+    false,
+    isDeferredListenerForLegacyFBSupport,
+  );
+  return true;
 }
 
 function isMatchingRootContainer(
@@ -303,12 +286,19 @@ export function dispatchEventForPluginEventSystem(
       // TODO: useEvent for document and window
       return;
     }
-    // If we detect the FB legacy primer system, we
+    // If we are using the legacy FB support flag, we
     // defer the event to the null with a one
     // time event listener so we can defer the event.
     if (
-      enableLegacyFBPrimerSupport &&
-      willDeferLaterForFBLegacyPrimer(nativeEvent)
+      enableLegacyFBSupport &&
+      // We do not want to defer if the event system has already been
+      // set to LEGACY_FB_SUPPORT. LEGACY_FB_SUPPORT only gets set when
+      // we call willDeferLaterForLegacyFBSupport, thus not bailing out
+      // will result in endless cycles like an infinite loop.
+      (eventSystemFlags & LEGACY_FB_SUPPORT) === 0 &&
+      // We also don't want to defer during event replaying.
+      (eventSystemFlags & IS_REPLAYED) === 0 &&
+      willDeferLaterForLegacyFBSupport(topLevelType, targetContainer)
     ) {
       return;
     }

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

@@ -42,6 +42,7 @@ import {
   IS_PASSIVE,
   IS_ACTIVE,
   PASSIVE_NOT_SUPPORTED,
+  LEGACY_FB_SUPPORT,
 } from 'legacy-events/EventSystemFlags';
 
 import {
@@ -59,7 +60,7 @@ import {passiveBrowserEventsSupported} from './checkPassiveEvents';
 import {
   enableDeprecatedFlareAPI,
   enableModernEventSystem,
-  enableLegacyFBPrimerSupport,
+  enableLegacyFBSupport,
   enableUseEventAPI,
 } from 'shared/ReactFeatureFlags';
 import {
@@ -129,10 +130,10 @@ export function addResponderEventSystemEvent(
 }
 
 export function addTrappedEventListener(
-  targetContainer: null | EventTarget,
+  targetContainer: EventTarget,
   topLevelType: DOMTopLevelEventType,
   capture: boolean,
-  legacyFBSupport?: boolean,
+  isDeferredListenerForLegacyFBSupport?: boolean,
   passive?: boolean,
   priority?: EventPriority,
 ): any => void {
@@ -159,11 +160,15 @@ export function addTrappedEventListener(
   if (passive === true && !passiveBrowserEventsSupported) {
     passive = false;
   }
+  const eventSystemFlags =
+    enableLegacyFBSupport && isDeferredListenerForLegacyFBSupport
+      ? PLUGIN_EVENT_SYSTEM | LEGACY_FB_SUPPORT
+      : PLUGIN_EVENT_SYSTEM;
 
   listener = listenerWrapper.bind(
     null,
     topLevelType,
-    PLUGIN_EVENT_SYSTEM,
+    eventSystemFlags,
     targetContainer,
   );
 
@@ -177,14 +182,17 @@ export function addTrappedEventListener(
     targetContainer = document;
   }
 
-  const validTargetContainer = ((targetContainer: any): EventTarget);
+  targetContainer =
+    enableLegacyFBSupport && isDeferredListenerForLegacyFBSupport
+      ? (targetContainer: any).ownerDocument
+      : targetContainer;
 
   const rawEventName = getRawEventName(topLevelType);
 
   let unsubscribeListener;
   // When legacyFBSupport is enabled, it's for when we
   // want to add a one time event listener to a container.
-  // This should only be used with enableLegacyFBPrimerSupport
+  // This should only be used with enableLegacyFBSupport
   // due to requirement to provide compatibility with
   // internal FB www event tooling. This works by removing
   // the event listener as soon as it is invoked. We could
@@ -193,14 +201,14 @@ export function addTrappedEventListener(
   // browsers do not support this today, and given this is
   // to support legacy code patterns, it's likely they'll
   // need support for such browsers.
-  if (enableLegacyFBPrimerSupport && legacyFBSupport) {
+  if (enableLegacyFBSupport && isDeferredListenerForLegacyFBSupport) {
     const originalListener = listener;
     listener = function(...p) {
       try {
         return originalListener.apply(this, p);
       } finally {
         removeEventListener(
-          validTargetContainer,
+          targetContainer,
           rawEventName,
           unsubscribeListener,
           capture,
@@ -212,14 +220,14 @@ export function addTrappedEventListener(
     if (enableUseEventAPI && passive !== undefined) {
       // This is only used with passive is either true or false.
       unsubscribeListener = addEventCaptureListenerWithPassiveFlag(
-        validTargetContainer,
+        targetContainer,
         rawEventName,
         listener,
         passive,
       );
     } else {
       unsubscribeListener = addEventCaptureListener(
-        validTargetContainer,
+        targetContainer,
         rawEventName,
         listener,
       );
@@ -228,14 +236,14 @@ export function addTrappedEventListener(
     if (enableUseEventAPI && passive !== undefined) {
       // This is only used with passive is either true or false.
       unsubscribeListener = addEventBubbleListenerWithPassiveFlag(
-        validTargetContainer,
+        targetContainer,
         rawEventName,
         listener,
         passive,
       );
     } else {
       unsubscribeListener = addEventBubbleListener(
-        validTargetContainer,
+        targetContainer,
         rawEventName,
         listener,
       );
@@ -249,7 +257,6 @@ export function removeTrappedEventListener(
   topLevelType: DOMTopLevelEventType,
   capture: boolean,
   listener: any => void,
-  passive: void | boolean,
 ): void {
   const rawEventName = getRawEventName(topLevelType);
   removeEventListener(targetContainer, rawEventName, listener, capture);