Modern Event System: Add support for internal FB Primer

Author: trueadm

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

@@ -56,6 +56,9 @@ import {
   TOP_PROGRESS,
   TOP_PLAYING,
 } from './DOMTopLevelEventTypes';
+import {DOCUMENT_NODE} from '../shared/HTMLNodeType';
+
+import {enableLegacyFBPrimerSupport} from 'shared/ReactFeatureFlags';
 
 const capturePhaseEvents = new Set([
   TOP_FOCUS,
@@ -165,6 +168,40 @@ export function listenToEvent(
   }
 }
 
+const validFBLegacyPrimerRels = new Set([
+  'dialog',
+  'dialog-post',
+  'async',
+  'async-post',
+  'theater',
+  'toggle',
+]);
+
+function willDeferLaterForFBLegacyPrimer(nativeEvent: any): boolean {
+  let node = nativeEvent.target;
+
+  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;
+      trapEventForPluginEventSystem(
+        document,
+        nativeEvent.type,
+        false,
+        legacyFBSupport,
+      );
+      return true;
+    }
+    node = node.parentNode;
+  }
+  return false;
+}
+
 export function dispatchEventForPluginEventSystem(
   topLevelType: DOMTopLevelEventType,
   eventSystemFlags: EventSystemFlags,
@@ -173,6 +210,17 @@ export function dispatchEventForPluginEventSystem(
   rootContainer: Document | Element,
 ): void {
   let ancestorInst = targetInst;
+  if (rootContainer.nodeType !== DOCUMENT_NODE) {
+    // If we detect the FB legacy primer system, we
+    // defer the event to the "document" with a one
+    // time event listener so we can defer the event.
+    if (
+      enableLegacyFBPrimerSupport &&
+      willDeferLaterForFBLegacyPrimer(nativeEvent)
+    ) {
+      return;
+    }
+  }
 
   batchedEventUpdates(() =>
     dispatchEventsForPlugins(

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

@@ -56,6 +56,7 @@ import {passiveBrowserEventsSupported} from './checkPassiveEvents';
 import {
   enableDeprecatedFlareAPI,
   enableModernEventSystem,
+  enableLegacyFBPrimerSupport,
 } from 'shared/ReactFeatureFlags';
 import {
   UserBlockingEvent,
@@ -143,6 +144,7 @@ export function trapEventForPluginEventSystem(
   container: Document | Element,
   topLevelType: DOMTopLevelEventType,
   capture: boolean,
+  legacyFBSupport?: boolean,
 ): void {
   let listener;
   let listenerWrapper;
@@ -166,10 +168,40 @@ export function trapEventForPluginEventSystem(
   );
 
   const rawEventName = getRawEventName(topLevelType);
+  let fbListener;
+
+  // 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
+  // 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
+  // also attempt to use the {once: true} param on
+  // addEventListener, but that requires support and some
+  // 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) {
+    const originalListener = listener;
+    listener = function(...p) {
+      try {
+        return originalListener.apply(this, p);
+      } finally {
+        if (fbListener) {
+          fbListener.remove();
+        } else {
+          container.removeEventListener(
+            ((rawEventName: any): string),
+            (listener: any),
+          );
+        }
+      }
+    };
+  }
   if (capture) {
-    addEventCaptureListener(container, rawEventName, listener);
+    fbListener = addEventCaptureListener(container, rawEventName, listener);
   } else {
-    addEventBubbleListener(container, rawEventName, listener);
+    fbListener = addEventBubbleListener(container, rawEventName, listener);
   }
 }
 

packages/react-dom/src/events/__tests__/DOMModernPluginEventSystem-test.internal.js

@@ -119,4 +119,35 @@ describe('DOMModernPluginEventSystem', () => {
     expect(log[4]).toEqual(['bubble', divElement]);
     expect(log[5]).toEqual(['bubble', buttonElement]);
   });
+
+  it('handle propagation of click events correctly with primer', () => {
+    const aRef = React.createRef();
+    const log = [];
+    // Stop propagation throught the React system
+    const onClick = jest.fn(e => e.stopPropagation());
+
+    function Test() {
+      return (
+        <a ref={aRef} href="#" onClick={onClick} rel="dialog">
+          Click me
+        </a>
+      );
+    }
+
+    ReactDOM.render(<Test />, container);
+
+    // Fake primer
+    document.addEventListener('click', e => {
+      if (e.target.rel === 'dialog') {
+        log.push('primer');
+      }
+    });
+
+    ReactFeatureFlags.enableLegacyFBPrimerSupport = true;
+    let aElement = aRef.current;
+    dispatchClickEvent(aElement);
+    expect(onClick).toHaveBeenCalledTimes(1);
+    expect(log).toEqual(['primer']);
+    ReactFeatureFlags.enableLegacyFBPrimerSupport = false;
+  });
 });

packages/shared/ReactFeatureFlags.js

@@ -128,3 +128,6 @@ export const warnUnstableRenderSubtreeIntoContainer = false;
 
 // Modern event system where events get registered at roots
 export const enableModernEventSystem = false;
+
+// Support legacy Primer support on internal FB www
+export const enableLegacyFBPrimerSupport = false;

packages/shared/forks/ReactFeatureFlags.native-fb.js

@@ -44,6 +44,7 @@ export const deferPassiveEffectCleanupDuringUnmount = false;
 export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
+export const enableLegacyFBPrimerSupport = false;
 
 // Internal-only attempt to debug a React Native issue. See D20130868.
 export const throwEarlyForMysteriousError = true;

packages/shared/forks/ReactFeatureFlags.native-oss.js

@@ -43,6 +43,7 @@ export const deferPassiveEffectCleanupDuringUnmount = false;
 export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
+export const enableLegacyFBPrimerSupport = false;
 
 // Internal-only attempt to debug a React Native issue. See D20130868.
 export const throwEarlyForMysteriousError = false;

packages/shared/forks/ReactFeatureFlags.persistent.js

@@ -43,6 +43,7 @@ export const deferPassiveEffectCleanupDuringUnmount = false;
 export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
+export const enableLegacyFBPrimerSupport = false;
 
 // Internal-only attempt to debug a React Native issue. See D20130868.
 export const throwEarlyForMysteriousError = false;

packages/shared/forks/ReactFeatureFlags.test-renderer.js

@@ -43,6 +43,7 @@ export const deferPassiveEffectCleanupDuringUnmount = false;
 export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
+export const enableLegacyFBPrimerSupport = false;
 
 // Internal-only attempt to debug a React Native issue. See D20130868.
 export const throwEarlyForMysteriousError = false;

packages/shared/forks/ReactFeatureFlags.test-renderer.www.js

@@ -43,6 +43,7 @@ export const deferPassiveEffectCleanupDuringUnmount = false;
 export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
+export const enableLegacyFBPrimerSupport = false;
 
 // Internal-only attempt to debug a React Native issue. See D20130868.
 export const throwEarlyForMysteriousError = false;

packages/shared/forks/ReactFeatureFlags.testing.js

@@ -43,6 +43,7 @@ export const deferPassiveEffectCleanupDuringUnmount = false;
 export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
+export const enableLegacyFBPrimerSupport = false;
 
 // Internal-only attempt to debug a React Native issue. See D20130868.
 export const throwEarlyForMysteriousError = false;