Add infrastructure for passive/non-passive event support for future A…

…PI exploration (#15036)

* Add infrastructure for passive/non-passive event support for future event API experimentation

packages/events/EventSystemFlags.js

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+export type EventSystemFlags = number;
+
+export const PLUGIN_EVENT_SYSTEM = 1;
+export const RESPONDER_EVENT_SYSTEM = 1 << 1;
+export const IS_PASSIVE = 1 << 2;
+export const IS_ACTIVE = 1 << 3;
+export const PASSIVE_NOT_SUPPORTED = 1 << 4;

packages/events/ReactGenericBatching.js

@@ -20,8 +20,8 @@ import {
 let _batchedUpdatesImpl = function(fn, bookkeeping) {
   return fn(bookkeeping);
 };
-let _interactiveUpdatesImpl = function(fn, a, b) {
-  return fn(a, b);
+let _interactiveUpdatesImpl = function(fn, a, b, c) {
+  return fn(a, b, c);
 };
 let _flushInteractiveUpdatesImpl = function() {};
 
@@ -52,8 +52,8 @@ export function batchedUpdates(fn, bookkeeping) {
   }
 }
 
-export function interactiveUpdates(fn, a, b) {
-  return _interactiveUpdatesImpl(fn, a, b);
+export function interactiveUpdates(fn, a, b, c) {
+  return _interactiveUpdatesImpl(fn, a, b, c);
 }
 
 export function flushInteractiveUpdates() {

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

@@ -253,7 +253,10 @@ if (__DEV__) {
   };
 }
 
-function ensureListeningTo(rootContainerElement, registrationName) {
+function ensureListeningTo(
+  rootContainerElement: Element | Node,
+  registrationName: string,
+): void {
   const isDocumentOrFragment =
     rootContainerElement.nodeType === DOCUMENT_NODE ||
     rootContainerElement.nodeType === DOCUMENT_FRAGMENT_NODE;

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

@@ -8,17 +8,26 @@
  */
 
 export function addEventBubbleListener(
-  element: Document | Element,
+  element: Document | Element | Node,
   eventType: string,
   listener: Function,
 ): void {
   element.addEventListener(eventType, listener, false);
 }
 
 export function addEventCaptureListener(
-  element: Document | Element,
+  element: Document | Element | Node,
   eventType: string,
   listener: Function,
 ): void {
   element.addEventListener(eventType, listener, true);
 }
+
+export function addEventListener(
+  element: Document | Element | Node,
+  eventType: string,
+  listener: Function,
+  options: {passive: boolean},
+): void {
+  element.addEventListener(eventType, listener, (options: any));
+}

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

@@ -8,6 +8,7 @@
  */
 
 import {registrationNameDependencies} from 'events/EventPluginRegistry';
+import type {DOMTopLevelEventType} from 'events/TopLevelEventTypes';
 import {
   TOP_BLUR,
   TOP_CANCEL,
@@ -84,22 +85,23 @@ import isEventSupported from './isEventSupported';
  *    React Core     .  General Purpose Event Plugin System
  */
 
-const alreadyListeningTo = {};
-let reactTopListenersCounter = 0;
+const PossiblyWeakMap = typeof WeakMap === 'function' ? WeakMap : Map;
+const elementListeningSets:
+  | WeakMap
+  | Map<
+      Document | Element | Node,
+      Set<DOMTopLevelEventType>,
+    > = new PossiblyWeakMap();
 
-/**
- * To ensure no conflicts with other potential React instances on the page
- */
-const topListenersIDKey = '_reactListenersID' + ('' + Math.random()).slice(2);
-
-function getListeningForDocument(mountAt: any) {
-  // In IE8, `mountAt` is a host object and doesn't have `hasOwnProperty`
-  // directly.
-  if (!Object.prototype.hasOwnProperty.call(mountAt, topListenersIDKey)) {
-    mountAt[topListenersIDKey] = reactTopListenersCounter++;
-    alreadyListeningTo[mountAt[topListenersIDKey]] = {};
+function getListeningSetForElement(
+  element: Document | Element | Node,
+): Set<DOMTopLevelEventType> {
+  let listeningSet = elementListeningSets.get(element);
+  if (listeningSet === undefined) {
+    listeningSet = new Set();
+    elementListeningSets.set(element, listeningSet);
   }
-  return alreadyListeningTo[mountAt[topListenersIDKey]];
+  return listeningSet;
 }
 
 /**
@@ -125,14 +127,14 @@ function getListeningForDocument(mountAt: any) {
  */
 export function listenTo(
   registrationName: string,
-  mountAt: Document | Element,
-) {
-  const isListening = getListeningForDocument(mountAt);
+  mountAt: Document | Element | Node,
+): void {
+  const listeningSet = getListeningSetForElement(mountAt);
   const dependencies = registrationNameDependencies[registrationName];
 
   for (let i = 0; i < dependencies.length; i++) {
     const dependency = dependencies[i];
-    if (!(isListening.hasOwnProperty(dependency) && isListening[dependency])) {
+    if (!listeningSet.has(dependency)) {
       switch (dependency) {
         case TOP_SCROLL:
           trapCapturedEvent(TOP_SCROLL, mountAt);
@@ -143,8 +145,8 @@ export function listenTo(
           trapCapturedEvent(TOP_BLUR, mountAt);
           // We set the flag for a single dependency later in this function,
           // but this ensures we mark both as attached rather than just one.
-          isListening[TOP_BLUR] = true;
-          isListening[TOP_FOCUS] = true;
+          listeningSet.add(TOP_BLUR);
+          listeningSet.add(TOP_FOCUS);
           break;
         case TOP_CANCEL:
         case TOP_CLOSE:
@@ -167,20 +169,21 @@ export function listenTo(
           }
           break;
       }
-      isListening[dependency] = true;
+      listeningSet.add(dependency);
     }
   }
 }
 
 export function isListeningToAllDependencies(
   registrationName: string,
   mountAt: Document | Element,
-) {
-  const isListening = getListeningForDocument(mountAt);
+): boolean {
+  const listeningSet = getListeningSetForElement(mountAt);
   const dependencies = registrationNameDependencies[registrationName];
+
   for (let i = 0; i < dependencies.length; i++) {
     const dependency = dependencies[i];
-    if (!(isListening.hasOwnProperty(dependency) && isListening[dependency])) {
+    if (!listeningSet.has(dependency)) {
       return false;
     }
   }