From 8c9fc4e90f58fab25c2991ac60ddb6a6afe9271c Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Mon, 24 Aug 2020 16:10:23 +0100
Subject: [PATCH] Remove usage of PossiblyWeakSet from createEventHandle
 (#19686)

---
 .../src/client/ReactDOMComponentTree.js       | 28 ++++++++++++++++++-
 .../src/client/ReactDOMEventHandle.js         | 14 +++++-----
 2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/packages/react-dom/src/client/ReactDOMComponentTree.js b/packages/react-dom/src/client/ReactDOMComponentTree.js
index d5f09c1caf45d..d0edca73baee5 100644
--- a/packages/react-dom/src/client/ReactDOMComponentTree.js
+++ b/packages/react-dom/src/client/ReactDOMComponentTree.js
@@ -9,7 +9,10 @@
 
 import type {Fiber} from 'react-reconciler/src/ReactInternalTypes';
 import type {ReactScopeInstance} from 'shared/ReactTypes';
-import type {ReactDOMEventHandleListener} from '../shared/ReactDOMTypes';
+import type {
+  ReactDOMEventHandle,
+  ReactDOMEventHandleListener,
+} from '../shared/ReactDOMTypes';
 import type {
   Container,
   TextInstance,
@@ -39,6 +42,7 @@ const internalPropsKey = '__reactProps$' + randomKey;
 const internalContainerInstanceKey = '__reactContainer$' + randomKey;
 const internalEventHandlersKey = '__reactEvents$' + randomKey;
 const internalEventHandlerListenersKey = '__reactListeners$' + randomKey;
+const internalEventHandlesSetKey = '__reactHandles$' + randomKey;
 
 export type ElementListenerMap = Map<
   DOMEventName | string,
@@ -232,3 +236,25 @@ export function getEventHandlerListeners(
 ): null | Set<ReactDOMEventHandleListener> {
   return (scope: any)[internalEventHandlerListenersKey] || null;
 }
+
+export function addEventHandleToTarget(
+  target: EventTarget | ReactScopeInstance,
+  eventHandle: ReactDOMEventHandle,
+): void {
+  let eventHandles = (target: any)[internalEventHandlesSetKey];
+  if (eventHandles === undefined) {
+    eventHandles = (target: any)[internalEventHandlesSetKey] = new Set();
+  }
+  eventHandles.add(eventHandle);
+}
+
+export function doesTargetHaveEventHandle(
+  target: EventTarget | ReactScopeInstance,
+  eventHandle: ReactDOMEventHandle,
+): boolean {
+  const eventHandles = (target: any)[internalEventHandlesSetKey];
+  if (eventHandles === undefined) {
+    return false;
+  }
+  return eventHandles.has(eventHandle);
+}
diff --git a/packages/react-dom/src/client/ReactDOMEventHandle.js b/packages/react-dom/src/client/ReactDOMEventHandle.js
index 19e69126aef0c..303b083313e98 100644
--- a/packages/react-dom/src/client/ReactDOMEventHandle.js
+++ b/packages/react-dom/src/client/ReactDOMEventHandle.js
@@ -20,6 +20,8 @@ import {
   getEventHandlerListeners,
   setEventHandlerListeners,
   getFiberFromScopeInstance,
+  doesTargetHaveEventHandle,
+  addEventHandleToTarget,
 } from './ReactDOMComponentTree';
 import {ELEMENT_NODE, COMMENT_NODE} from '../shared/HTMLNodeType';
 import {
@@ -42,8 +44,6 @@ type EventHandleOptions = {|
   priority?: EventPriority,
 |};
 
-const PossiblyWeakSet = typeof WeakSet === 'function' ? WeakSet : Set;
-
 function getNearestRootOrPortalContainer(node: Fiber): null | Element {
   while (node !== null) {
     const tag = node.tag;
@@ -201,9 +201,7 @@ export function createEventHandle(
       listenerPriority = getEventPriorityForListenerSystem(domEventName);
     }
 
-    const registeredReactDOMEvents = new PossiblyWeakSet();
-
-    return (
+    const eventHandle = (
       target: EventTarget | ReactScopeInstance,
       callback: (SyntheticEvent<EventTarget>) => void,
     ) => {
@@ -212,8 +210,8 @@ export function createEventHandle(
         'ReactDOM.createEventHandle: setter called with an invalid ' +
           'callback. The callback must be a function.',
       );
-      if (!registeredReactDOMEvents.has(target)) {
-        registeredReactDOMEvents.add(target);
+      if (!doesTargetHaveEventHandle(target, eventHandle)) {
+        addEventHandleToTarget(target, eventHandle);
         registerReactDOMEvent(
           target,
           domEventName,
@@ -241,6 +239,8 @@ export function createEventHandle(
         );
       };
     };
+
+    return eventHandle;
   }
   return (null: any);
 }