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rubennorterubennorte
authored
[react-native-renderer] EventTarget-based event dispatching (#36253)
## Summary Set up the experiment to migrate event dispatching in the React Native renderer to be based on the native EventTarget API. Behind the `enableNativeEventTargetEventDispatching` flag, events are dispatched through `dispatchTrustedEvent` instead of the legacy plugin system. Regular event handler props are NOT registered via addEventListener at commit time. Instead, a hook on EventTarget (`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from `canonical.currentProps` at dispatch time, shifting cost from every render to only when events fire. The hook is overridden in ReactNativeElement to look up the prop name via a reverse mapping from event names (built lazily from the view config registry). Responder events bypass EventTarget entirely. `negotiateResponder` walks the fiber tree directly (capture then bubble phase), calling handlers from `canonical.currentProps` and checking return values inline. Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers directly from props and inspect return values — `onResponderGrant` returning `true` blocks native responder, `onResponderTerminationRequest` returning `false` refuses termination. This eliminates all commit-time cost for responder events (no wrappers, no addEventListener, no `responderWrappers` on canonical). ## How did you test this change? Flow Tested e2e in RN using Fantom tests (that will land after this).
1 parent fef12a0 commit 5682442

10 files changed

Lines changed: 775 additions & 16 deletions

File tree

‎.eslintrc.js‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -463,6 +463,7 @@ module.exports = {
463463
globals: {
464464
nativeFabricUIManager: 'readonly',
465465
RN$enableMicrotasksInReact: 'readonly',
466+
RN$isNativeEventTargetEventDispatchingEnabled: 'readonly',
466467
},
467468
},
468469
{

‎packages/react-native-renderer/src/LegacySyntheticEvent.js‎

Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/**
2+
* Copyright (c) Meta Platforms, Inc. and affiliates.
3+
*
4+
* This source code is licensed under the MIT license found in the
5+
* LICENSE file in the root directory of this source tree.
6+
*
7+
* @flow
8+
*/
9+
10+
/* globals Event$Init */
11+
12+
/**
13+
* A bridge event class that extends the W3C Event interface and carries
14+
* the native event payload. This is used as a compatibility layer during
15+
* the migration from the legacy SyntheticEvent system to EventTarget-based
16+
* dispatching.
17+
*/
18+
exportdefaultclassLegacySyntheticEventextendsEvent{
19+
_nativeEvent: {[string]: mixed};
20+
_propagationStopped: boolean;
21+
22+
constructor(
23+
type: string,
24+
options: Event$Init,
25+
nativeEvent: {[string]: mixed},
26+
){
27+
super(type,options);
28+
this._nativeEvent=nativeEvent;
29+
this._propagationStopped=false;
30+
}
31+
32+
getnativeEvent(): {[string]: mixed}{
33+
returnthis._nativeEvent;
34+
}
35+
36+
stopPropagation(): void{
37+
super.stopPropagation();
38+
this._propagationStopped=true;
39+
}
40+
41+
stopImmediatePropagation(): void{
42+
super.stopImmediatePropagation();
43+
this._propagationStopped=true;
44+
}
45+
46+
/**
47+
* No-op for backward compatibility. The legacy SyntheticEvent system
48+
* used pooling which required calling persist() to keep the event.
49+
* With EventTarget-based dispatching, events are never pooled.
50+
*/
51+
persist(): void{
52+
// No-op
53+
}
54+
55+
/**
56+
* Backward-compatible wrapper for `defaultPrevented`.
57+
*/
58+
isDefaultPrevented(): boolean{
59+
returnthis.defaultPrevented;
60+
}
61+
62+
/**
63+
* Backward-compatible wrapper. Returns true if stopPropagation()
64+
* has been called.
65+
*/
66+
isPropagationStopped(): boolean{
67+
returnthis._propagationStopped;
68+
}
69+
}

‎packages/react-native-renderer/src/ReactFabricEventEmitter.js‎

Lines changed: 65 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -28,11 +28,23 @@ import accumulateInto from './legacy-events/accumulateInto';
2828
importgetListenerfrom'./ReactNativeGetListener';
2929
import{runEventsInBatch}from'./legacy-events/EventBatching';
3030

31-
import{RawEventEmitter}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
31+
import{
32+
RawEventEmitter,
33+
ReactNativeViewConfigRegistry,
34+
dispatchTrustedEvent,
35+
setEventInitTimeStamp,
36+
}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
3237
import{getPublicInstance}from'./ReactFiberConfigFabric';
38+
importLegacySyntheticEventfrom'./LegacySyntheticEvent';
39+
import{topLevelTypeToEventName}from'./ReactNativeEventTypeMapping';
40+
import{processResponderEvent}from'./ReactNativeResponder';
41+
import{enableNativeEventTargetEventDispatching}from'./ReactNativeFeatureFlags';
3342

3443
export{getListener,registrationNameModulesasregistrationNames};
3544

45+
const{customBubblingEventTypes, customDirectEventTypes}=
46+
ReactNativeViewConfigRegistry;
47+
3648
/**
3749
* Allows registered plugins an opportunity to extract events from top-level
3850
* native browser events.
@@ -47,10 +59,12 @@ function extractPluginEvents(
4759
nativeEventTarget: null|EventTarget,
4860
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
4961
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
50-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
62+
constlegacyPlugins=((plugins: any): Array<
63+
LegacyPluginModule<AnyNativeEvent>,
64+
>);
5165
for(leti=0;i<legacyPlugins.length;i++){
5266
// Not every plugin in the ordering may be loaded at runtime.
53-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
67+
const possiblePlugin =legacyPlugins[i];
5468
if(possiblePlugin){
5569
const extractedEvents =possiblePlugin.extractEvents(
5670
topLevelType,
@@ -84,8 +98,12 @@ function runExtractedPluginEventsInBatch(
8498
exportfunctiondispatchEvent(
8599
target: null|Object,
86100
topLevelType: RNTopLevelEventType,
87-
nativeEvent: AnyNativeEvent,
101+
nativeEventParam: mixed,
88102
){
103+
constnativeEvent: AnyNativeEvent=
104+
nativeEventParam!=null&&typeofnativeEventParam==='object'
105+
? (nativeEventParam: any)
106+
: {};
89107
consttargetFiber=(target: null|Fiber);
90108

91109
leteventTarget=null;
@@ -121,18 +139,52 @@ export function dispatchEvent(
121139
// Note that extracted events are *not* emitted,
122140
// only events that have a 1:1 mapping with a native event, at least for now.
123141
constevent={eventName: topLevelType, nativeEvent};
124-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
125142
RawEventEmitter.emit(topLevelType,event);
126-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
127143
RawEventEmitter.emit('*',event);
128144

129-
// Heritage plugin event system
130-
runExtractedPluginEventsInBatch(
131-
topLevelType,
132-
targetFiber,
133-
nativeEvent,
134-
eventTarget,
135-
);
145+
if(enableNativeEventTargetEventDispatching()){
146+
// Process responder events before normal event dispatch.
147+
// This handles touch negotiation (onStartShouldSetResponder, etc.)
148+
processResponderEvent(topLevelType,targetFiber,nativeEvent);
149+
150+
// New EventTarget-based dispatch path
151+
if(eventTarget!=null){
152+
constbubbleDispatchConfig=customBubblingEventTypes[topLevelType];
153+
constdirectDispatchConfig=customDirectEventTypes[topLevelType];
154+
constbubbles=bubbleDispatchConfig!=null;
155+
156+
// Skip events that are not registered in the view config
157+
if(bubbles||directDispatchConfig!=null){
158+
consteventName=topLevelTypeToEventName(topLevelType);
159+
constoptions={
160+
bubbles,
161+
cancelable: true,
162+
};
163+
// Preserve the native event timestamp for backwards compatibility.
164+
// The legacy SyntheticEvent system used nativeEvent.timeStamp || nativeEvent.timestamp.
165+
constnativeTimestamp=
166+
nativeEvent.timeStamp??nativeEvent.timestamp;
167+
if(typeofnativeTimestamp==='number'){
168+
setEventInitTimeStamp(options,nativeTimestamp);
169+
}
170+
constsyntheticEvent=newLegacySyntheticEvent(
171+
eventName,
172+
options,
173+
nativeEvent,
174+
);
175+
// $FlowFixMe[incompatible-call]
176+
dispatchTrustedEvent(eventTarget,syntheticEvent);
177+
}
178+
}
179+
}else{
180+
// Heritage plugin event system
181+
runExtractedPluginEventsInBatch(
182+
topLevelType,
183+
targetFiber,
184+
nativeEvent,
185+
eventTarget,
186+
);
187+
}
136188
});
137189
// React Native doesn't use ReactControlledComponent but if it did, here's
138190
// where it would do it.

‎packages/react-native-renderer/src/ReactNativeEventEmitter.js‎

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -131,10 +131,12 @@ function extractPluginEvents(
131131
nativeEventTarget: null|EventTarget,
132132
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
133133
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
134-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
134+
constlegacyPlugins=((plugins: any): Array<
135+
LegacyPluginModule<AnyNativeEvent>,
136+
>);
135137
for(leti=0;i<legacyPlugins.length;i++){
136138
// Not every plugin in the ordering may be loaded at runtime.
137-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
139+
const possiblePlugin =legacyPlugins[i];
138140
if(possiblePlugin){
139141
const extractedEvents =possiblePlugin.extractEvents(
140142
topLevelType,

‎packages/react-native-renderer/src/ReactNativeEventTypeMapping.js‎

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
/**
2+
* Copyright (c) Meta Platforms, Inc. and affiliates.
3+
*
4+
* This source code is licensed under the MIT license found in the
5+
* LICENSE file in the root directory of this source tree.
6+
*
7+
* @flow
8+
*/
9+
10+
/**
11+
* Converts a topLevelType (e.g., "topPress") to a DOM event name (e.g., "press").
12+
* Strips the "top" prefix and lowercases the result.
13+
*/
14+
exportfunctiontopLevelTypeToEventName(topLevelType: string): string{
15+
constfourthChar=topLevelType.charCodeAt(3);
16+
if(
17+
topLevelType.startsWith('top')&&
18+
fourthChar>=65/* A */&&
19+
fourthChar<=90/* Z */
20+
){
21+
returntopLevelType.slice(3).toLowerCase();
22+
}
23+
returntopLevelType;
24+
}

‎packages/react-native-renderer/src/ReactNativeFeatureFlags.js‎

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
* Copyright (c) Meta Platforms, Inc. and affiliates.
3+
*
4+
* This source code is licensed under the MIT license found in the
5+
* LICENSE file in the root directory of this source tree.
6+
*
7+
* @flow
8+
*/
9+
10+
// These globals are set by React Native (e.g. in setUpDOM.js, setUpTimers.js)
11+
// and provide access to RN's feature flags. We use global functions because we
12+
// don't have another mechanism to pass feature flags from RN to React in OSS.
13+
// Values are lazily evaluated and cached on first access.
14+
15+
let_enableNativeEventTargetEventDispatching: boolean|null=null;
16+
exportfunctionenableNativeEventTargetEventDispatching(): boolean{
17+
if(_enableNativeEventTargetEventDispatching==null){
18+
_enableNativeEventTargetEventDispatching=
19+
typeofRN$isNativeEventTargetEventDispatchingEnabled==='function'&&
20+
RN$isNativeEventTargetEventDispatchingEnabled();
21+
}
22+
return_enableNativeEventTargetEventDispatching;
23+
}

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[react-native-renderer] EventTarget-based event dispatching (#36253) · react/react@5682442 · GitHub
Skip to content
Commit 5682442
Browse files
rubennorterubennorte
authored
[react-native-renderer] EventTarget-based event dispatching (#36253)
## Summary
Set up the experiment to migrate event dispatching in the React Native
renderer to be based on the native EventTarget API.
Behind the `enableNativeEventTargetEventDispatching` flag, events are
dispatched through `dispatchTrustedEvent` instead of the legacy plugin
system.
Regular event handler props are NOT registered via addEventListener at
commit time. Instead, a hook on EventTarget
(`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from
`canonical.currentProps` at dispatch time, shifting cost from every
render to only when events fire. The hook is overridden in
ReactNativeElement to look up the prop name via a reverse mapping from
event names (built lazily from the view config registry).
Responder events bypass EventTarget entirely. `negotiateResponder` walks
the fiber tree directly (capture then bubble phase), calling handlers
from `canonical.currentProps` and checking return values inline.
Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers
directly from props and inspect return values — `onResponderGrant`
returning `true` blocks native responder,
`onResponderTerminationRequest` returning `false` refuses termination.
This eliminates all commit-time cost for responder events (no wrappers,
no addEventListener, no `responderWrappers` on canonical).
## How did you test this change?
Flow
Tested e2e in RN using Fantom tests (that will land after this).
1 parent fef12a0 commit 5682442
10 files changed
Lines changed: 775 additions & 16 deletions
File tree
‎.eslintrc.js‎
Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -463,6 +463,7 @@ module.exports = {
463463
globals: {
464464
nativeFabricUIManager: 'readonly',
465465
RN$enableMicrotasksInReact: 'readonly',
466+
RN$isNativeEventTargetEventDispatchingEnabled: 'readonly',
466467
},
467468
},
468469
{
‎packages/react-native-renderer/src/LegacySyntheticEvent.js‎
Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/* globals Event$Init */
11+
12+
/**
13+
 * A bridge event class that extends the W3C Event interface and carries
14+
 * the native event payload. This is used as a compatibility layer during
15+
 * the migration from the legacy SyntheticEvent system to EventTarget-based
16+
 * dispatching.
17+
 */
18+
exportdefaultclassLegacySyntheticEventextendsEvent{
19+
_nativeEvent: {[string]: mixed};
20+
 _propagationStopped: boolean;
21+
22+
constructor(
23+
type: string,
24+
options: Event$Init,
25+
nativeEvent: {[string]: mixed},
26+
){
27+
super(type,options);
28+
this._nativeEvent=nativeEvent;
29+
this._propagationStopped=false;
30+
}
31+
32+
getnativeEvent(): {[string]: mixed}{
33+
returnthis._nativeEvent;
34+
}
35+
36+
stopPropagation(): void{
37+
 super.stopPropagation();
38+
this._propagationStopped=true;
39+
}
40+
41+
stopImmediatePropagation(): void{
42+
 super.stopImmediatePropagation();
43+
this._propagationStopped=true;
44+
}
45+
46+
/**
47+
 * No-op for backward compatibility. The legacy SyntheticEvent system
48+
 * used pooling which required calling persist() to keep the event.
49+
 * With EventTarget-based dispatching, events are never pooled.
50+
 */
51+
persist(): void{
52+
// No-op
53+
}
54+
55+
/**
56+
 * Backward-compatible wrapper for `defaultPrevented`.
57+
 */
58+
isDefaultPrevented(): boolean{
59+
returnthis.defaultPrevented;
60+
}
61+
62+
/**
63+
 * Backward-compatible wrapper. Returns true if stopPropagation()
64+
 * has been called.
65+
 */
66+
isPropagationStopped(): boolean{
67+
returnthis._propagationStopped;
68+
}
69+
}
‎packages/react-native-renderer/src/ReactFabricEventEmitter.js‎
Lines changed: 65 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -28,11 +28,23 @@ import accumulateInto from './legacy-events/accumulateInto';
2828
importgetListenerfrom'./ReactNativeGetListener';
2929
import{runEventsInBatch}from'./legacy-events/EventBatching';
3030

31-
import{RawEventEmitter}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
31+
import{
32+
RawEventEmitter,
33+
ReactNativeViewConfigRegistry,
34+
dispatchTrustedEvent,
35+
setEventInitTimeStamp,
36+
}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
3237
import{getPublicInstance}from'./ReactFiberConfigFabric';
38+
importLegacySyntheticEventfrom'./LegacySyntheticEvent';
39+
import{topLevelTypeToEventName}from'./ReactNativeEventTypeMapping';
40+
import{processResponderEvent}from'./ReactNativeResponder';
41+
import{enableNativeEventTargetEventDispatching}from'./ReactNativeFeatureFlags';
3342

3443
export{getListener,registrationNameModulesasregistrationNames};
3544

45+
const{customBubblingEventTypes, customDirectEventTypes}=
46+
ReactNativeViewConfigRegistry;
47+
3648
/**
3749
 * Allows registered plugins an opportunity to extract events from top-level
3850
 * native browser events.
@@ -47,10 +59,12 @@ function extractPluginEvents(
4759
nativeEventTarget: null|EventTarget,
4860
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
4961
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
50-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
62+
constlegacyPlugins=((plugins: any): Array<
63+
LegacyPluginModule<AnyNativeEvent>,
64+
>);
5165
for(leti=0;i<legacyPlugins.length;i++){
5266
// Not every plugin in the ordering may be loaded at runtime.
53-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
67+
const possiblePlugin =legacyPlugins[i];
5468
if(possiblePlugin){
5569
const extractedEvents =possiblePlugin.extractEvents(
5670
topLevelType,
@@ -84,8 +98,12 @@ function runExtractedPluginEventsInBatch(
8498
exportfunctiondispatchEvent(
8599
target: null|Object,
86100
topLevelType: RNTopLevelEventType,
87-
nativeEvent: AnyNativeEvent,
101+
nativeEventParam: mixed,
88102
){
103+
constnativeEvent: AnyNativeEvent=
104+
nativeEventParam!=null&&typeofnativeEventParam==='object'
105+
 ? (nativeEventParam: any)
106+
 : {};
89107
consttargetFiber=(target: null|Fiber);
90108

91109
leteventTarget=null;
@@ -121,18 +139,52 @@ export function dispatchEvent(
121139
// Note that extracted events are *not* emitted,
122140
// only events that have a 1:1 mapping with a native event, at least for now.
123141
constevent={eventName: topLevelType, nativeEvent};
124-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
125142
RawEventEmitter.emit(topLevelType,event);
126-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
127143
RawEventEmitter.emit('*',event);
128144

129-
// Heritage plugin event system
130-
runExtractedPluginEventsInBatch(
131-
topLevelType,
132-
targetFiber,
133-
nativeEvent,
134-
eventTarget,
135-
);
145+
if(enableNativeEventTargetEventDispatching()){
146+
// Process responder events before normal event dispatch.
147+
// This handles touch negotiation (onStartShouldSetResponder, etc.)
148+
processResponderEvent(topLevelType,targetFiber,nativeEvent);
149+
150+
// New EventTarget-based dispatch path
151+
if(eventTarget!=null){
152+
constbubbleDispatchConfig=customBubblingEventTypes[topLevelType];
153+
constdirectDispatchConfig=customDirectEventTypes[topLevelType];
154+
constbubbles=bubbleDispatchConfig!=null;
155+
156+
// Skip events that are not registered in the view config
157+
if(bubbles||directDispatchConfig!=null){
158+
consteventName=topLevelTypeToEventName(topLevelType);
159+
constoptions={
160+
 bubbles,
161+
cancelable: true,
162+
};
163+
// Preserve the native event timestamp for backwards compatibility.
164+
// The legacy SyntheticEvent system used nativeEvent.timeStamp || nativeEvent.timestamp.
165+
constnativeTimestamp=
166+
nativeEvent.timeStamp??nativeEvent.timestamp;
167+
if(typeofnativeTimestamp==='number'){
168+
setEventInitTimeStamp(options,nativeTimestamp);
169+
}
170+
constsyntheticEvent=newLegacySyntheticEvent(
171+
eventName,
172+
options,
173+
nativeEvent,
174+
);
175+
// $FlowFixMe[incompatible-call]
176+
dispatchTrustedEvent(eventTarget,syntheticEvent);
177+
}
178+
}
179+
}else{
180+
// Heritage plugin event system
181+
runExtractedPluginEventsInBatch(
182+
topLevelType,
183+
targetFiber,
184+
nativeEvent,
185+
eventTarget,
186+
);
187+
}
136188
});
137189
// React Native doesn't use ReactControlledComponent but if it did, here's
138190
// where it would do it.
‎packages/react-native-renderer/src/ReactNativeEventEmitter.js‎
Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -131,10 +131,12 @@ function extractPluginEvents(
131131
nativeEventTarget: null|EventTarget,
132132
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
133133
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
134-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
134+
constlegacyPlugins=((plugins: any): Array<
135+
LegacyPluginModule<AnyNativeEvent>,
136+
>);
135137
for(leti=0;i<legacyPlugins.length;i++){
136138
// Not every plugin in the ordering may be loaded at runtime.
137-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
139+
const possiblePlugin =legacyPlugins[i];
138140
if(possiblePlugin){
139141
const extractedEvents =possiblePlugin.extractEvents(
140142
topLevelType,
‎packages/react-native-renderer/src/ReactNativeEventTypeMapping.js‎
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/**
11+
 * Converts a topLevelType (e.g., "topPress") to a DOM event name (e.g., "press").
12+
 * Strips the "top" prefix and lowercases the result.
13+
 */
14+
exportfunctiontopLevelTypeToEventName(topLevelType: string): string{
15+
constfourthChar=topLevelType.charCodeAt(3);
16+
if(
17+
topLevelType.startsWith('top')&&
18+
fourthChar>=65/* A */&&
19+
fourthChar<=90/* Z */
20+
){
21+
returntopLevelType.slice(3).toLowerCase();
22+
}
23+
returntopLevelType;
24+
}
‎packages/react-native-renderer/src/ReactNativeFeatureFlags.js‎
Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
// These globals are set by React Native (e.g. in setUpDOM.js, setUpTimers.js)
11+
// and provide access to RN's feature flags. We use global functions because we
12+
// don't have another mechanism to pass feature flags from RN to React in OSS.
13+
// Values are lazily evaluated and cached on first access.
14+
15+
let_enableNativeEventTargetEventDispatching: boolean|null=null;
16+
exportfunctionenableNativeEventTargetEventDispatching(): boolean{
17+
if(_enableNativeEventTargetEventDispatching==null){
18+
_enableNativeEventTargetEventDispatching=
19+
typeofRN$isNativeEventTargetEventDispatchingEnabled==='function'&&
20+
RN$isNativeEventTargetEventDispatchingEnabled();
21+
}
22+
return_enableNativeEventTargetEventDispatching;
23+
}
0 commit comments
Comments
 (0)

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(function() {
var style = document.createElement('style');
style.textContent = '
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color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
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[react-native-renderer] EventTarget-based event dispatching (#36253) · react/react@5682442 · GitHub
Skip to content
Commit 5682442
Browse files
rubennorterubennorte
authored
[react-native-renderer] EventTarget-based event dispatching (#36253)
## Summary
Set up the experiment to migrate event dispatching in the React Native
renderer to be based on the native EventTarget API.
Behind the `enableNativeEventTargetEventDispatching` flag, events are
dispatched through `dispatchTrustedEvent` instead of the legacy plugin
system.
Regular event handler props are NOT registered via addEventListener at
commit time. Instead, a hook on EventTarget
(`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from
`canonical.currentProps` at dispatch time, shifting cost from every
render to only when events fire. The hook is overridden in
ReactNativeElement to look up the prop name via a reverse mapping from
event names (built lazily from the view config registry).
Responder events bypass EventTarget entirely. `negotiateResponder` walks
the fiber tree directly (capture then bubble phase), calling handlers
from `canonical.currentProps` and checking return values inline.
Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers
directly from props and inspect return values — `onResponderGrant`
returning `true` blocks native responder,
`onResponderTerminationRequest` returning `false` refuses termination.
This eliminates all commit-time cost for responder events (no wrappers,
no addEventListener, no `responderWrappers` on canonical).
## How did you test this change?
Flow
Tested e2e in RN using Fantom tests (that will land after this).
1 parent fef12a0 commit 5682442
10 files changed
Lines changed: 775 additions & 16 deletions
File tree
‎.eslintrc.js‎
Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -463,6 +463,7 @@ module.exports = {
463463
globals: {
464464
nativeFabricUIManager: 'readonly',
465465
RN$enableMicrotasksInReact: 'readonly',
466+
RN$isNativeEventTargetEventDispatchingEnabled: 'readonly',
466467
},
467468
},
468469
{
‎packages/react-native-renderer/src/LegacySyntheticEvent.js‎
Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/* globals Event$Init */
11+
12+
/**
13+
 * A bridge event class that extends the W3C Event interface and carries
14+
 * the native event payload. This is used as a compatibility layer during
15+
 * the migration from the legacy SyntheticEvent system to EventTarget-based
16+
 * dispatching.
17+
 */
18+
exportdefaultclassLegacySyntheticEventextendsEvent{
19+
_nativeEvent: {[string]: mixed};
20+
 _propagationStopped: boolean;
21+
22+
constructor(
23+
type: string,
24+
options: Event$Init,
25+
nativeEvent: {[string]: mixed},
26+
){
27+
super(type,options);
28+
this._nativeEvent=nativeEvent;
29+
this._propagationStopped=false;
30+
}
31+
32+
getnativeEvent(): {[string]: mixed}{
33+
returnthis._nativeEvent;
34+
}
35+
36+
stopPropagation(): void{
37+
 super.stopPropagation();
38+
this._propagationStopped=true;
39+
}
40+
41+
stopImmediatePropagation(): void{
42+
 super.stopImmediatePropagation();
43+
this._propagationStopped=true;
44+
}
45+
46+
/**
47+
 * No-op for backward compatibility. The legacy SyntheticEvent system
48+
 * used pooling which required calling persist() to keep the event.
49+
 * With EventTarget-based dispatching, events are never pooled.
50+
 */
51+
persist(): void{
52+
// No-op
53+
}
54+
55+
/**
56+
 * Backward-compatible wrapper for `defaultPrevented`.
57+
 */
58+
isDefaultPrevented(): boolean{
59+
returnthis.defaultPrevented;
60+
}
61+
62+
/**
63+
 * Backward-compatible wrapper. Returns true if stopPropagation()
64+
 * has been called.
65+
 */
66+
isPropagationStopped(): boolean{
67+
returnthis._propagationStopped;
68+
}
69+
}
‎packages/react-native-renderer/src/ReactFabricEventEmitter.js‎
Lines changed: 65 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -28,11 +28,23 @@ import accumulateInto from './legacy-events/accumulateInto';
2828
importgetListenerfrom'./ReactNativeGetListener';
2929
import{runEventsInBatch}from'./legacy-events/EventBatching';
3030

31-
import{RawEventEmitter}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
31+
import{
32+
RawEventEmitter,
33+
ReactNativeViewConfigRegistry,
34+
dispatchTrustedEvent,
35+
setEventInitTimeStamp,
36+
}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
3237
import{getPublicInstance}from'./ReactFiberConfigFabric';
38+
importLegacySyntheticEventfrom'./LegacySyntheticEvent';
39+
import{topLevelTypeToEventName}from'./ReactNativeEventTypeMapping';
40+
import{processResponderEvent}from'./ReactNativeResponder';
41+
import{enableNativeEventTargetEventDispatching}from'./ReactNativeFeatureFlags';
3342

3443
export{getListener,registrationNameModulesasregistrationNames};
3544

45+
const{customBubblingEventTypes, customDirectEventTypes}=
46+
ReactNativeViewConfigRegistry;
47+
3648
/**
3749
 * Allows registered plugins an opportunity to extract events from top-level
3850
 * native browser events.
@@ -47,10 +59,12 @@ function extractPluginEvents(
4759
nativeEventTarget: null|EventTarget,
4860
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
4961
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
50-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
62+
constlegacyPlugins=((plugins: any): Array<
63+
LegacyPluginModule<AnyNativeEvent>,
64+
>);
5165
for(leti=0;i<legacyPlugins.length;i++){
5266
// Not every plugin in the ordering may be loaded at runtime.
53-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
67+
const possiblePlugin =legacyPlugins[i];
5468
if(possiblePlugin){
5569
const extractedEvents =possiblePlugin.extractEvents(
5670
topLevelType,
@@ -84,8 +98,12 @@ function runExtractedPluginEventsInBatch(
8498
exportfunctiondispatchEvent(
8599
target: null|Object,
86100
topLevelType: RNTopLevelEventType,
87-
nativeEvent: AnyNativeEvent,
101+
nativeEventParam: mixed,
88102
){
103+
constnativeEvent: AnyNativeEvent=
104+
nativeEventParam!=null&&typeofnativeEventParam==='object'
105+
 ? (nativeEventParam: any)
106+
 : {};
89107
consttargetFiber=(target: null|Fiber);
90108

91109
leteventTarget=null;
@@ -121,18 +139,52 @@ export function dispatchEvent(
121139
// Note that extracted events are *not* emitted,
122140
// only events that have a 1:1 mapping with a native event, at least for now.
123141
constevent={eventName: topLevelType, nativeEvent};
124-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
125142
RawEventEmitter.emit(topLevelType,event);
126-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
127143
RawEventEmitter.emit('*',event);
128144

129-
// Heritage plugin event system
130-
runExtractedPluginEventsInBatch(
131-
topLevelType,
132-
targetFiber,
133-
nativeEvent,
134-
eventTarget,
135-
);
145+
if(enableNativeEventTargetEventDispatching()){
146+
// Process responder events before normal event dispatch.
147+
// This handles touch negotiation (onStartShouldSetResponder, etc.)
148+
processResponderEvent(topLevelType,targetFiber,nativeEvent);
149+
150+
// New EventTarget-based dispatch path
151+
if(eventTarget!=null){
152+
constbubbleDispatchConfig=customBubblingEventTypes[topLevelType];
153+
constdirectDispatchConfig=customDirectEventTypes[topLevelType];
154+
constbubbles=bubbleDispatchConfig!=null;
155+
156+
// Skip events that are not registered in the view config
157+
if(bubbles||directDispatchConfig!=null){
158+
consteventName=topLevelTypeToEventName(topLevelType);
159+
constoptions={
160+
 bubbles,
161+
cancelable: true,
162+
};
163+
// Preserve the native event timestamp for backwards compatibility.
164+
// The legacy SyntheticEvent system used nativeEvent.timeStamp || nativeEvent.timestamp.
165+
constnativeTimestamp=
166+
nativeEvent.timeStamp??nativeEvent.timestamp;
167+
if(typeofnativeTimestamp==='number'){
168+
setEventInitTimeStamp(options,nativeTimestamp);
169+
}
170+
constsyntheticEvent=newLegacySyntheticEvent(
171+
eventName,
172+
options,
173+
nativeEvent,
174+
);
175+
// $FlowFixMe[incompatible-call]
176+
dispatchTrustedEvent(eventTarget,syntheticEvent);
177+
}
178+
}
179+
}else{
180+
// Heritage plugin event system
181+
runExtractedPluginEventsInBatch(
182+
topLevelType,
183+
targetFiber,
184+
nativeEvent,
185+
eventTarget,
186+
);
187+
}
136188
});
137189
// React Native doesn't use ReactControlledComponent but if it did, here's
138190
// where it would do it.
‎packages/react-native-renderer/src/ReactNativeEventEmitter.js‎
Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -131,10 +131,12 @@ function extractPluginEvents(
131131
nativeEventTarget: null|EventTarget,
132132
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
133133
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
134-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
134+
constlegacyPlugins=((plugins: any): Array<
135+
LegacyPluginModule<AnyNativeEvent>,
136+
>);
135137
for(leti=0;i<legacyPlugins.length;i++){
136138
// Not every plugin in the ordering may be loaded at runtime.
137-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
139+
const possiblePlugin =legacyPlugins[i];
138140
if(possiblePlugin){
139141
const extractedEvents =possiblePlugin.extractEvents(
140142
topLevelType,
‎packages/react-native-renderer/src/ReactNativeEventTypeMapping.js‎
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/**
11+
 * Converts a topLevelType (e.g., "topPress") to a DOM event name (e.g., "press").
12+
 * Strips the "top" prefix and lowercases the result.
13+
 */
14+
exportfunctiontopLevelTypeToEventName(topLevelType: string): string{
15+
constfourthChar=topLevelType.charCodeAt(3);
16+
if(
17+
topLevelType.startsWith('top')&&
18+
fourthChar>=65/* A */&&
19+
fourthChar<=90/* Z */
20+
){
21+
returntopLevelType.slice(3).toLowerCase();
22+
}
23+
returntopLevelType;
24+
}
‎packages/react-native-renderer/src/ReactNativeFeatureFlags.js‎
Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
// These globals are set by React Native (e.g. in setUpDOM.js, setUpTimers.js)
11+
// and provide access to RN's feature flags. We use global functions because we
12+
// don't have another mechanism to pass feature flags from RN to React in OSS.
13+
// Values are lazily evaluated and cached on first access.
14+
15+
let_enableNativeEventTargetEventDispatching: boolean|null=null;
16+
exportfunctionenableNativeEventTargetEventDispatching(): boolean{
17+
if(_enableNativeEventTargetEventDispatching==null){
18+
_enableNativeEventTargetEventDispatching=
19+
typeofRN$isNativeEventTargetEventDispatchingEnabled==='function'&&
20+
RN$isNativeEventTargetEventDispatchingEnabled();
21+
}
22+
return_enableNativeEventTargetEventDispatching;
23+
}
0 commit comments
Comments
 (0)

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
[react-native-renderer] EventTarget-based event dispatching (#36253) · react/react@5682442 · GitHub
Skip to content
Commit 5682442
Browse files
rubennorterubennorte
authored
[react-native-renderer] EventTarget-based event dispatching (#36253)
## Summary
Set up the experiment to migrate event dispatching in the React Native
renderer to be based on the native EventTarget API.
Behind the `enableNativeEventTargetEventDispatching` flag, events are
dispatched through `dispatchTrustedEvent` instead of the legacy plugin
system.
Regular event handler props are NOT registered via addEventListener at
commit time. Instead, a hook on EventTarget
(`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from
`canonical.currentProps` at dispatch time, shifting cost from every
render to only when events fire. The hook is overridden in
ReactNativeElement to look up the prop name via a reverse mapping from
event names (built lazily from the view config registry).
Responder events bypass EventTarget entirely. `negotiateResponder` walks
the fiber tree directly (capture then bubble phase), calling handlers
from `canonical.currentProps` and checking return values inline.
Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers
directly from props and inspect return values — `onResponderGrant`
returning `true` blocks native responder,
`onResponderTerminationRequest` returning `false` refuses termination.
This eliminates all commit-time cost for responder events (no wrappers,
no addEventListener, no `responderWrappers` on canonical).
## How did you test this change?
Flow
Tested e2e in RN using Fantom tests (that will land after this).
1 parent fef12a0 commit 5682442
10 files changed
Lines changed: 775 additions & 16 deletions
File tree
‎.eslintrc.js‎
Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -463,6 +463,7 @@ module.exports = {
463463
globals: {
464464
nativeFabricUIManager: 'readonly',
465465
RN$enableMicrotasksInReact: 'readonly',
466+
RN$isNativeEventTargetEventDispatchingEnabled: 'readonly',
466467
},
467468
},
468469
{
‎packages/react-native-renderer/src/LegacySyntheticEvent.js‎
Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/* globals Event$Init */
11+
12+
/**
13+
 * A bridge event class that extends the W3C Event interface and carries
14+
 * the native event payload. This is used as a compatibility layer during
15+
 * the migration from the legacy SyntheticEvent system to EventTarget-based
16+
 * dispatching.
17+
 */
18+
exportdefaultclassLegacySyntheticEventextendsEvent{
19+
_nativeEvent: {[string]: mixed};
20+
 _propagationStopped: boolean;
21+
22+
constructor(
23+
type: string,
24+
options: Event$Init,
25+
nativeEvent: {[string]: mixed},
26+
){
27+
super(type,options);
28+
this._nativeEvent=nativeEvent;
29+
this._propagationStopped=false;
30+
}
31+
32+
getnativeEvent(): {[string]: mixed}{
33+
returnthis._nativeEvent;
34+
}
35+
36+
stopPropagation(): void{
37+
 super.stopPropagation();
38+
this._propagationStopped=true;
39+
}
40+
41+
stopImmediatePropagation(): void{
42+
 super.stopImmediatePropagation();
43+
this._propagationStopped=true;
44+
}
45+
46+
/**
47+
 * No-op for backward compatibility. The legacy SyntheticEvent system
48+
 * used pooling which required calling persist() to keep the event.
49+
 * With EventTarget-based dispatching, events are never pooled.
50+
 */
51+
persist(): void{
52+
// No-op
53+
}
54+
55+
/**
56+
 * Backward-compatible wrapper for `defaultPrevented`.
57+
 */
58+
isDefaultPrevented(): boolean{
59+
returnthis.defaultPrevented;
60+
}
61+
62+
/**
63+
 * Backward-compatible wrapper. Returns true if stopPropagation()
64+
 * has been called.
65+
 */
66+
isPropagationStopped(): boolean{
67+
returnthis._propagationStopped;
68+
}
69+
}
‎packages/react-native-renderer/src/ReactFabricEventEmitter.js‎
Lines changed: 65 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -28,11 +28,23 @@ import accumulateInto from './legacy-events/accumulateInto';
2828
importgetListenerfrom'./ReactNativeGetListener';
2929
import{runEventsInBatch}from'./legacy-events/EventBatching';
3030

31-
import{RawEventEmitter}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
31+
import{
32+
RawEventEmitter,
33+
ReactNativeViewConfigRegistry,
34+
dispatchTrustedEvent,
35+
setEventInitTimeStamp,
36+
}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
3237
import{getPublicInstance}from'./ReactFiberConfigFabric';
38+
importLegacySyntheticEventfrom'./LegacySyntheticEvent';
39+
import{topLevelTypeToEventName}from'./ReactNativeEventTypeMapping';
40+
import{processResponderEvent}from'./ReactNativeResponder';
41+
import{enableNativeEventTargetEventDispatching}from'./ReactNativeFeatureFlags';
3342

3443
export{getListener,registrationNameModulesasregistrationNames};
3544

45+
const{customBubblingEventTypes, customDirectEventTypes}=
46+
ReactNativeViewConfigRegistry;
47+
3648
/**
3749
 * Allows registered plugins an opportunity to extract events from top-level
3850
 * native browser events.
@@ -47,10 +59,12 @@ function extractPluginEvents(
4759
nativeEventTarget: null|EventTarget,
4860
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
4961
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
50-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
62+
constlegacyPlugins=((plugins: any): Array<
63+
LegacyPluginModule<AnyNativeEvent>,
64+
>);
5165
for(leti=0;i<legacyPlugins.length;i++){
5266
// Not every plugin in the ordering may be loaded at runtime.
53-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
67+
const possiblePlugin =legacyPlugins[i];
5468
if(possiblePlugin){
5569
const extractedEvents =possiblePlugin.extractEvents(
5670
topLevelType,
@@ -84,8 +98,12 @@ function runExtractedPluginEventsInBatch(
8498
exportfunctiondispatchEvent(
8599
target: null|Object,
86100
topLevelType: RNTopLevelEventType,
87-
nativeEvent: AnyNativeEvent,
101+
nativeEventParam: mixed,
88102
){
103+
constnativeEvent: AnyNativeEvent=
104+
nativeEventParam!=null&&typeofnativeEventParam==='object'
105+
 ? (nativeEventParam: any)
106+
 : {};
89107
consttargetFiber=(target: null|Fiber);
90108

91109
leteventTarget=null;
@@ -121,18 +139,52 @@ export function dispatchEvent(
121139
// Note that extracted events are *not* emitted,
122140
// only events that have a 1:1 mapping with a native event, at least for now.
123141
constevent={eventName: topLevelType, nativeEvent};
124-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
125142
RawEventEmitter.emit(topLevelType,event);
126-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
127143
RawEventEmitter.emit('*',event);
128144

129-
// Heritage plugin event system
130-
runExtractedPluginEventsInBatch(
131-
topLevelType,
132-
targetFiber,
133-
nativeEvent,
134-
eventTarget,
135-
);
145+
if(enableNativeEventTargetEventDispatching()){
146+
// Process responder events before normal event dispatch.
147+
// This handles touch negotiation (onStartShouldSetResponder, etc.)
148+
processResponderEvent(topLevelType,targetFiber,nativeEvent);
149+
150+
// New EventTarget-based dispatch path
151+
if(eventTarget!=null){
152+
constbubbleDispatchConfig=customBubblingEventTypes[topLevelType];
153+
constdirectDispatchConfig=customDirectEventTypes[topLevelType];
154+
constbubbles=bubbleDispatchConfig!=null;
155+
156+
// Skip events that are not registered in the view config
157+
if(bubbles||directDispatchConfig!=null){
158+
consteventName=topLevelTypeToEventName(topLevelType);
159+
constoptions={
160+
 bubbles,
161+
cancelable: true,
162+
};
163+
// Preserve the native event timestamp for backwards compatibility.
164+
// The legacy SyntheticEvent system used nativeEvent.timeStamp || nativeEvent.timestamp.
165+
constnativeTimestamp=
166+
nativeEvent.timeStamp??nativeEvent.timestamp;
167+
if(typeofnativeTimestamp==='number'){
168+
setEventInitTimeStamp(options,nativeTimestamp);
169+
}
170+
constsyntheticEvent=newLegacySyntheticEvent(
171+
eventName,
172+
options,
173+
nativeEvent,
174+
);
175+
// $FlowFixMe[incompatible-call]
176+
dispatchTrustedEvent(eventTarget,syntheticEvent);
177+
}
178+
}
179+
}else{
180+
// Heritage plugin event system
181+
runExtractedPluginEventsInBatch(
182+
topLevelType,
183+
targetFiber,
184+
nativeEvent,
185+
eventTarget,
186+
);
187+
}
136188
});
137189
// React Native doesn't use ReactControlledComponent but if it did, here's
138190
// where it would do it.
‎packages/react-native-renderer/src/ReactNativeEventEmitter.js‎
Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -131,10 +131,12 @@ function extractPluginEvents(
131131
nativeEventTarget: null|EventTarget,
132132
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
133133
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
134-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
134+
constlegacyPlugins=((plugins: any): Array<
135+
LegacyPluginModule<AnyNativeEvent>,
136+
>);
135137
for(leti=0;i<legacyPlugins.length;i++){
136138
// Not every plugin in the ordering may be loaded at runtime.
137-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
139+
const possiblePlugin =legacyPlugins[i];
138140
if(possiblePlugin){
139141
const extractedEvents =possiblePlugin.extractEvents(
140142
topLevelType,
‎packages/react-native-renderer/src/ReactNativeEventTypeMapping.js‎
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/**
11+
 * Converts a topLevelType (e.g., "topPress") to a DOM event name (e.g., "press").
12+
 * Strips the "top" prefix and lowercases the result.
13+
 */
14+
exportfunctiontopLevelTypeToEventName(topLevelType: string): string{
15+
constfourthChar=topLevelType.charCodeAt(3);
16+
if(
17+
topLevelType.startsWith('top')&&
18+
fourthChar>=65/* A */&&
19+
fourthChar<=90/* Z */
20+
){
21+
returntopLevelType.slice(3).toLowerCase();
22+
}
23+
returntopLevelType;
24+
}
‎packages/react-native-renderer/src/ReactNativeFeatureFlags.js‎
Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
// These globals are set by React Native (e.g. in setUpDOM.js, setUpTimers.js)
11+
// and provide access to RN's feature flags. We use global functions because we
12+
// don't have another mechanism to pass feature flags from RN to React in OSS.
13+
// Values are lazily evaluated and cached on first access.
14+
15+
let_enableNativeEventTargetEventDispatching: boolean|null=null;
16+
exportfunctionenableNativeEventTargetEventDispatching(): boolean{
17+
if(_enableNativeEventTargetEventDispatching==null){
18+
_enableNativeEventTargetEventDispatching=
19+
typeofRN$isNativeEventTargetEventDispatchingEnabled==='function'&&
20+
RN$isNativeEventTargetEventDispatchingEnabled();
21+
}
22+
return_enableNativeEventTargetEventDispatching;
23+
}
0 commit comments
Comments
 (0)

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
[react-native-renderer] EventTarget-based event dispatching (#36253) · react/react@5682442 · GitHub
Skip to content
Commit 5682442
Browse files
rubennorterubennorte
authored
[react-native-renderer] EventTarget-based event dispatching (#36253)
## Summary
Set up the experiment to migrate event dispatching in the React Native
renderer to be based on the native EventTarget API.
Behind the `enableNativeEventTargetEventDispatching` flag, events are
dispatched through `dispatchTrustedEvent` instead of the legacy plugin
system.
Regular event handler props are NOT registered via addEventListener at
commit time. Instead, a hook on EventTarget
(`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from
`canonical.currentProps` at dispatch time, shifting cost from every
render to only when events fire. The hook is overridden in
ReactNativeElement to look up the prop name via a reverse mapping from
event names (built lazily from the view config registry).
Responder events bypass EventTarget entirely. `negotiateResponder` walks
the fiber tree directly (capture then bubble phase), calling handlers
from `canonical.currentProps` and checking return values inline.
Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers
directly from props and inspect return values — `onResponderGrant`
returning `true` blocks native responder,
`onResponderTerminationRequest` returning `false` refuses termination.
This eliminates all commit-time cost for responder events (no wrappers,
no addEventListener, no `responderWrappers` on canonical).
## How did you test this change?
Flow
Tested e2e in RN using Fantom tests (that will land after this).
1 parent fef12a0 commit 5682442
10 files changed
Lines changed: 775 additions & 16 deletions
File tree
‎.eslintrc.js‎
Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -463,6 +463,7 @@ module.exports = {
463463
globals: {
464464
nativeFabricUIManager: 'readonly',
465465
RN$enableMicrotasksInReact: 'readonly',
466+
RN$isNativeEventTargetEventDispatchingEnabled: 'readonly',
466467
},
467468
},
468469
{
‎packages/react-native-renderer/src/LegacySyntheticEvent.js‎
Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/* globals Event$Init */
11+
12+
/**
13+
 * A bridge event class that extends the W3C Event interface and carries
14+
 * the native event payload. This is used as a compatibility layer during
15+
 * the migration from the legacy SyntheticEvent system to EventTarget-based
16+
 * dispatching.
17+
 */
18+
exportdefaultclassLegacySyntheticEventextendsEvent{
19+
_nativeEvent: {[string]: mixed};
20+
 _propagationStopped: boolean;
21+
22+
constructor(
23+
type: string,
24+
options: Event$Init,
25+
nativeEvent: {[string]: mixed},
26+
){
27+
super(type,options);
28+
this._nativeEvent=nativeEvent;
29+
this._propagationStopped=false;
30+
}
31+
32+
getnativeEvent(): {[string]: mixed}{
33+
returnthis._nativeEvent;
34+
}
35+
36+
stopPropagation(): void{
37+
 super.stopPropagation();
38+
this._propagationStopped=true;
39+
}
40+
41+
stopImmediatePropagation(): void{
42+
 super.stopImmediatePropagation();
43+
this._propagationStopped=true;
44+
}
45+
46+
/**
47+
 * No-op for backward compatibility. The legacy SyntheticEvent system
48+
 * used pooling which required calling persist() to keep the event.
49+
 * With EventTarget-based dispatching, events are never pooled.
50+
 */
51+
persist(): void{
52+
// No-op
53+
}
54+
55+
/**
56+
 * Backward-compatible wrapper for `defaultPrevented`.
57+
 */
58+
isDefaultPrevented(): boolean{
59+
returnthis.defaultPrevented;
60+
}
61+
62+
/**
63+
 * Backward-compatible wrapper. Returns true if stopPropagation()
64+
 * has been called.
65+
 */
66+
isPropagationStopped(): boolean{
67+
returnthis._propagationStopped;
68+
}
69+
}
‎packages/react-native-renderer/src/ReactFabricEventEmitter.js‎
Lines changed: 65 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -28,11 +28,23 @@ import accumulateInto from './legacy-events/accumulateInto';
2828
importgetListenerfrom'./ReactNativeGetListener';
2929
import{runEventsInBatch}from'./legacy-events/EventBatching';
3030

31-
import{RawEventEmitter}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
31+
import{
32+
RawEventEmitter,
33+
ReactNativeViewConfigRegistry,
34+
dispatchTrustedEvent,
35+
setEventInitTimeStamp,
36+
}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
3237
import{getPublicInstance}from'./ReactFiberConfigFabric';
38+
importLegacySyntheticEventfrom'./LegacySyntheticEvent';
39+
import{topLevelTypeToEventName}from'./ReactNativeEventTypeMapping';
40+
import{processResponderEvent}from'./ReactNativeResponder';
41+
import{enableNativeEventTargetEventDispatching}from'./ReactNativeFeatureFlags';
3342

3443
export{getListener,registrationNameModulesasregistrationNames};
3544

45+
const{customBubblingEventTypes, customDirectEventTypes}=
46+
ReactNativeViewConfigRegistry;
47+
3648
/**
3749
 * Allows registered plugins an opportunity to extract events from top-level
3850
 * native browser events.
@@ -47,10 +59,12 @@ function extractPluginEvents(
4759
nativeEventTarget: null|EventTarget,
4860
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
4961
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
50-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
62+
constlegacyPlugins=((plugins: any): Array<
63+
LegacyPluginModule<AnyNativeEvent>,
64+
>);
5165
for(leti=0;i<legacyPlugins.length;i++){
5266
// Not every plugin in the ordering may be loaded at runtime.
53-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
67+
const possiblePlugin =legacyPlugins[i];
5468
if(possiblePlugin){
5569
const extractedEvents =possiblePlugin.extractEvents(
5670
topLevelType,
@@ -84,8 +98,12 @@ function runExtractedPluginEventsInBatch(
8498
exportfunctiondispatchEvent(
8599
target: null|Object,
86100
topLevelType: RNTopLevelEventType,
87-
nativeEvent: AnyNativeEvent,
101+
nativeEventParam: mixed,
88102
){
103+
constnativeEvent: AnyNativeEvent=
104+
nativeEventParam!=null&&typeofnativeEventParam==='object'
105+
 ? (nativeEventParam: any)
106+
 : {};
89107
consttargetFiber=(target: null|Fiber);
90108

91109
leteventTarget=null;
@@ -121,18 +139,52 @@ export function dispatchEvent(
121139
// Note that extracted events are *not* emitted,
122140
// only events that have a 1:1 mapping with a native event, at least for now.
123141
constevent={eventName: topLevelType, nativeEvent};
124-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
125142
RawEventEmitter.emit(topLevelType,event);
126-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
127143
RawEventEmitter.emit('*',event);
128144

129-
// Heritage plugin event system
130-
runExtractedPluginEventsInBatch(
131-
topLevelType,
132-
targetFiber,
133-
nativeEvent,
134-
eventTarget,
135-
);
145+
if(enableNativeEventTargetEventDispatching()){
146+
// Process responder events before normal event dispatch.
147+
// This handles touch negotiation (onStartShouldSetResponder, etc.)
148+
processResponderEvent(topLevelType,targetFiber,nativeEvent);
149+
150+
// New EventTarget-based dispatch path
151+
if(eventTarget!=null){
152+
constbubbleDispatchConfig=customBubblingEventTypes[topLevelType];
153+
constdirectDispatchConfig=customDirectEventTypes[topLevelType];
154+
constbubbles=bubbleDispatchConfig!=null;
155+
156+
// Skip events that are not registered in the view config
157+
if(bubbles||directDispatchConfig!=null){
158+
consteventName=topLevelTypeToEventName(topLevelType);
159+
constoptions={
160+
 bubbles,
161+
cancelable: true,
162+
};
163+
// Preserve the native event timestamp for backwards compatibility.
164+
// The legacy SyntheticEvent system used nativeEvent.timeStamp || nativeEvent.timestamp.
165+
constnativeTimestamp=
166+
nativeEvent.timeStamp??nativeEvent.timestamp;
167+
if(typeofnativeTimestamp==='number'){
168+
setEventInitTimeStamp(options,nativeTimestamp);
169+
}
170+
constsyntheticEvent=newLegacySyntheticEvent(
171+
eventName,
172+
options,
173+
nativeEvent,
174+
);
175+
// $FlowFixMe[incompatible-call]
176+
dispatchTrustedEvent(eventTarget,syntheticEvent);
177+
}
178+
}
179+
}else{
180+
// Heritage plugin event system
181+
runExtractedPluginEventsInBatch(
182+
topLevelType,
183+
targetFiber,
184+
nativeEvent,
185+
eventTarget,
186+
);
187+
}
136188
});
137189
// React Native doesn't use ReactControlledComponent but if it did, here's
138190
// where it would do it.
‎packages/react-native-renderer/src/ReactNativeEventEmitter.js‎
Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -131,10 +131,12 @@ function extractPluginEvents(
131131
nativeEventTarget: null|EventTarget,
132132
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
133133
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
134-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
134+
constlegacyPlugins=((plugins: any): Array<
135+
LegacyPluginModule<AnyNativeEvent>,
136+
>);
135137
for(leti=0;i<legacyPlugins.length;i++){
136138
// Not every plugin in the ordering may be loaded at runtime.
137-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
139+
const possiblePlugin =legacyPlugins[i];
138140
if(possiblePlugin){
139141
const extractedEvents =possiblePlugin.extractEvents(
140142
topLevelType,
‎packages/react-native-renderer/src/ReactNativeEventTypeMapping.js‎
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/**
11+
 * Converts a topLevelType (e.g., "topPress") to a DOM event name (e.g., "press").
12+
 * Strips the "top" prefix and lowercases the result.
13+
 */
14+
exportfunctiontopLevelTypeToEventName(topLevelType: string): string{
15+
constfourthChar=topLevelType.charCodeAt(3);
16+
if(
17+
topLevelType.startsWith('top')&&
18+
fourthChar>=65/* A */&&
19+
fourthChar<=90/* Z */
20+
){
21+
returntopLevelType.slice(3).toLowerCase();
22+
}
23+
returntopLevelType;
24+
}
‎packages/react-native-renderer/src/ReactNativeFeatureFlags.js‎
Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
// These globals are set by React Native (e.g. in setUpDOM.js, setUpTimers.js)
11+
// and provide access to RN's feature flags. We use global functions because we
12+
// don't have another mechanism to pass feature flags from RN to React in OSS.
13+
// Values are lazily evaluated and cached on first access.
14+
15+
let_enableNativeEventTargetEventDispatching: boolean|null=null;
16+
exportfunctionenableNativeEventTargetEventDispatching(): boolean{
17+
if(_enableNativeEventTargetEventDispatching==null){
18+
_enableNativeEventTargetEventDispatching=
19+
typeofRN$isNativeEventTargetEventDispatchingEnabled==='function'&&
20+
RN$isNativeEventTargetEventDispatchingEnabled();
21+
}
22+
return_enableNativeEventTargetEventDispatching;
23+
}
0 commit comments
Comments
 (0)

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
[react-native-renderer] EventTarget-based event dispatching (#36253) · react/react@5682442 · GitHub
Skip to content
Commit 5682442
Browse files
rubennorterubennorte
authored
[react-native-renderer] EventTarget-based event dispatching (#36253)
## Summary
Set up the experiment to migrate event dispatching in the React Native
renderer to be based on the native EventTarget API.
Behind the `enableNativeEventTargetEventDispatching` flag, events are
dispatched through `dispatchTrustedEvent` instead of the legacy plugin
system.
Regular event handler props are NOT registered via addEventListener at
commit time. Instead, a hook on EventTarget
(`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from
`canonical.currentProps` at dispatch time, shifting cost from every
render to only when events fire. The hook is overridden in
ReactNativeElement to look up the prop name via a reverse mapping from
event names (built lazily from the view config registry).
Responder events bypass EventTarget entirely. `negotiateResponder` walks
the fiber tree directly (capture then bubble phase), calling handlers
from `canonical.currentProps` and checking return values inline.
Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers
directly from props and inspect return values — `onResponderGrant`
returning `true` blocks native responder,
`onResponderTerminationRequest` returning `false` refuses termination.
This eliminates all commit-time cost for responder events (no wrappers,
no addEventListener, no `responderWrappers` on canonical).
## How did you test this change?
Flow
Tested e2e in RN using Fantom tests (that will land after this).
1 parent fef12a0 commit 5682442
10 files changed
Lines changed: 775 additions & 16 deletions
File tree
‎.eslintrc.js‎
Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -463,6 +463,7 @@ module.exports = {
463463
globals: {
464464
nativeFabricUIManager: 'readonly',
465465
RN$enableMicrotasksInReact: 'readonly',
466+
RN$isNativeEventTargetEventDispatchingEnabled: 'readonly',
466467
},
467468
},
468469
{
‎packages/react-native-renderer/src/LegacySyntheticEvent.js‎
Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/* globals Event$Init */
11+
12+
/**
13+
 * A bridge event class that extends the W3C Event interface and carries
14+
 * the native event payload. This is used as a compatibility layer during
15+
 * the migration from the legacy SyntheticEvent system to EventTarget-based
16+
 * dispatching.
17+
 */
18+
exportdefaultclassLegacySyntheticEventextendsEvent{
19+
_nativeEvent: {[string]: mixed};
20+
 _propagationStopped: boolean;
21+
22+
constructor(
23+
type: string,
24+
options: Event$Init,
25+
nativeEvent: {[string]: mixed},
26+
){
27+
super(type,options);
28+
this._nativeEvent=nativeEvent;
29+
this._propagationStopped=false;
30+
}
31+
32+
getnativeEvent(): {[string]: mixed}{
33+
returnthis._nativeEvent;
34+
}
35+
36+
stopPropagation(): void{
37+
 super.stopPropagation();
38+
this._propagationStopped=true;
39+
}
40+
41+
stopImmediatePropagation(): void{
42+
 super.stopImmediatePropagation();
43+
this._propagationStopped=true;
44+
}
45+
46+
/**
47+
 * No-op for backward compatibility. The legacy SyntheticEvent system
48+
 * used pooling which required calling persist() to keep the event.
49+
 * With EventTarget-based dispatching, events are never pooled.
50+
 */
51+
persist(): void{
52+
// No-op
53+
}
54+
55+
/**
56+
 * Backward-compatible wrapper for `defaultPrevented`.
57+
 */
58+
isDefaultPrevented(): boolean{
59+
returnthis.defaultPrevented;
60+
}
61+
62+
/**
63+
 * Backward-compatible wrapper. Returns true if stopPropagation()
64+
 * has been called.
65+
 */
66+
isPropagationStopped(): boolean{
67+
returnthis._propagationStopped;
68+
}
69+
}
‎packages/react-native-renderer/src/ReactFabricEventEmitter.js‎
Lines changed: 65 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -28,11 +28,23 @@ import accumulateInto from './legacy-events/accumulateInto';
2828
importgetListenerfrom'./ReactNativeGetListener';
2929
import{runEventsInBatch}from'./legacy-events/EventBatching';
3030

31-
import{RawEventEmitter}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
31+
import{
32+
RawEventEmitter,
33+
ReactNativeViewConfigRegistry,
34+
dispatchTrustedEvent,
35+
setEventInitTimeStamp,
36+
}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
3237
import{getPublicInstance}from'./ReactFiberConfigFabric';
38+
importLegacySyntheticEventfrom'./LegacySyntheticEvent';
39+
import{topLevelTypeToEventName}from'./ReactNativeEventTypeMapping';
40+
import{processResponderEvent}from'./ReactNativeResponder';
41+
import{enableNativeEventTargetEventDispatching}from'./ReactNativeFeatureFlags';
3342

3443
export{getListener,registrationNameModulesasregistrationNames};
3544

45+
const{customBubblingEventTypes, customDirectEventTypes}=
46+
ReactNativeViewConfigRegistry;
47+
3648
/**
3749
 * Allows registered plugins an opportunity to extract events from top-level
3850
 * native browser events.
@@ -47,10 +59,12 @@ function extractPluginEvents(
4759
nativeEventTarget: null|EventTarget,
4860
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
4961
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
50-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
62+
constlegacyPlugins=((plugins: any): Array<
63+
LegacyPluginModule<AnyNativeEvent>,
64+
>);
5165
for(leti=0;i<legacyPlugins.length;i++){
5266
// Not every plugin in the ordering may be loaded at runtime.
53-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
67+
const possiblePlugin =legacyPlugins[i];
5468
if(possiblePlugin){
5569
const extractedEvents =possiblePlugin.extractEvents(
5670
topLevelType,
@@ -84,8 +98,12 @@ function runExtractedPluginEventsInBatch(
8498
exportfunctiondispatchEvent(
8599
target: null|Object,
86100
topLevelType: RNTopLevelEventType,
87-
nativeEvent: AnyNativeEvent,
101+
nativeEventParam: mixed,
88102
){
103+
constnativeEvent: AnyNativeEvent=
104+
nativeEventParam!=null&&typeofnativeEventParam==='object'
105+
 ? (nativeEventParam: any)
106+
 : {};
89107
consttargetFiber=(target: null|Fiber);
90108

91109
leteventTarget=null;
@@ -121,18 +139,52 @@ export function dispatchEvent(
121139
// Note that extracted events are *not* emitted,
122140
// only events that have a 1:1 mapping with a native event, at least for now.
123141
constevent={eventName: topLevelType, nativeEvent};
124-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
125142
RawEventEmitter.emit(topLevelType,event);
126-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
127143
RawEventEmitter.emit('*',event);
128144

129-
// Heritage plugin event system
130-
runExtractedPluginEventsInBatch(
131-
topLevelType,
132-
targetFiber,
133-
nativeEvent,
134-
eventTarget,
135-
);
145+
if(enableNativeEventTargetEventDispatching()){
146+
// Process responder events before normal event dispatch.
147+
// This handles touch negotiation (onStartShouldSetResponder, etc.)
148+
processResponderEvent(topLevelType,targetFiber,nativeEvent);
149+
150+
// New EventTarget-based dispatch path
151+
if(eventTarget!=null){
152+
constbubbleDispatchConfig=customBubblingEventTypes[topLevelType];
153+
constdirectDispatchConfig=customDirectEventTypes[topLevelType];
154+
constbubbles=bubbleDispatchConfig!=null;
155+
156+
// Skip events that are not registered in the view config
157+
if(bubbles||directDispatchConfig!=null){
158+
consteventName=topLevelTypeToEventName(topLevelType);
159+
constoptions={
160+
 bubbles,
161+
cancelable: true,
162+
};
163+
// Preserve the native event timestamp for backwards compatibility.
164+
// The legacy SyntheticEvent system used nativeEvent.timeStamp || nativeEvent.timestamp.
165+
constnativeTimestamp=
166+
nativeEvent.timeStamp??nativeEvent.timestamp;
167+
if(typeofnativeTimestamp==='number'){
168+
setEventInitTimeStamp(options,nativeTimestamp);
169+
}
170+
constsyntheticEvent=newLegacySyntheticEvent(
171+
eventName,
172+
options,
173+
nativeEvent,
174+
);
175+
// $FlowFixMe[incompatible-call]
176+
dispatchTrustedEvent(eventTarget,syntheticEvent);
177+
}
178+
}
179+
}else{
180+
// Heritage plugin event system
181+
runExtractedPluginEventsInBatch(
182+
topLevelType,
183+
targetFiber,
184+
nativeEvent,
185+
eventTarget,
186+
);
187+
}
136188
});
137189
// React Native doesn't use ReactControlledComponent but if it did, here's
138190
// where it would do it.
‎packages/react-native-renderer/src/ReactNativeEventEmitter.js‎
Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -131,10 +131,12 @@ function extractPluginEvents(
131131
nativeEventTarget: null|EventTarget,
132132
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
133133
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
134-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
134+
constlegacyPlugins=((plugins: any): Array<
135+
LegacyPluginModule<AnyNativeEvent>,
136+
>);
135137
for(leti=0;i<legacyPlugins.length;i++){
136138
// Not every plugin in the ordering may be loaded at runtime.
137-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
139+
const possiblePlugin =legacyPlugins[i];
138140
if(possiblePlugin){
139141
const extractedEvents =possiblePlugin.extractEvents(
140142
topLevelType,
‎packages/react-native-renderer/src/ReactNativeEventTypeMapping.js‎
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/**
11+
 * Converts a topLevelType (e.g., "topPress") to a DOM event name (e.g., "press").
12+
 * Strips the "top" prefix and lowercases the result.
13+
 */
14+
exportfunctiontopLevelTypeToEventName(topLevelType: string): string{
15+
constfourthChar=topLevelType.charCodeAt(3);
16+
if(
17+
topLevelType.startsWith('top')&&
18+
fourthChar>=65/* A */&&
19+
fourthChar<=90/* Z */
20+
){
21+
returntopLevelType.slice(3).toLowerCase();
22+
}
23+
returntopLevelType;
24+
}
‎packages/react-native-renderer/src/ReactNativeFeatureFlags.js‎
Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
// These globals are set by React Native (e.g. in setUpDOM.js, setUpTimers.js)
11+
// and provide access to RN's feature flags. We use global functions because we
12+
// don't have another mechanism to pass feature flags from RN to React in OSS.
13+
// Values are lazily evaluated and cached on first access.
14+
15+
let_enableNativeEventTargetEventDispatching: boolean|null=null;
16+
exportfunctionenableNativeEventTargetEventDispatching(): boolean{
17+
if(_enableNativeEventTargetEventDispatching==null){
18+
_enableNativeEventTargetEventDispatching=
19+
typeofRN$isNativeEventTargetEventDispatchingEnabled==='function'&&
20+
RN$isNativeEventTargetEventDispatchingEnabled();
21+
}
22+
return_enableNativeEventTargetEventDispatching;
23+
}
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[react-native-renderer] EventTarget-based event dispatching (#36253) · react/react@5682442 · GitHub
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Commit 5682442
Browse files
rubennorterubennorte
authored
[react-native-renderer] EventTarget-based event dispatching (#36253)
## Summary
Set up the experiment to migrate event dispatching in the React Native
renderer to be based on the native EventTarget API.
Behind the `enableNativeEventTargetEventDispatching` flag, events are
dispatched through `dispatchTrustedEvent` instead of the legacy plugin
system.
Regular event handler props are NOT registered via addEventListener at
commit time. Instead, a hook on EventTarget
(`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from
`canonical.currentProps` at dispatch time, shifting cost from every
render to only when events fire. The hook is overridden in
ReactNativeElement to look up the prop name via a reverse mapping from
event names (built lazily from the view config registry).
Responder events bypass EventTarget entirely. `negotiateResponder` walks
the fiber tree directly (capture then bubble phase), calling handlers
from `canonical.currentProps` and checking return values inline.
Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers
directly from props and inspect return values — `onResponderGrant`
returning `true` blocks native responder,
`onResponderTerminationRequest` returning `false` refuses termination.
This eliminates all commit-time cost for responder events (no wrappers,
no addEventListener, no `responderWrappers` on canonical).
## How did you test this change?
Flow
Tested e2e in RN using Fantom tests (that will land after this).
1 parent fef12a0 commit 5682442
10 files changed
Lines changed: 775 additions & 16 deletions
File tree
‎.eslintrc.js‎
Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -463,6 +463,7 @@ module.exports = {
463463
globals: {
464464
nativeFabricUIManager: 'readonly',
465465
RN$enableMicrotasksInReact: 'readonly',
466+
RN$isNativeEventTargetEventDispatchingEnabled: 'readonly',
466467
},
467468
},
468469
{
‎packages/react-native-renderer/src/LegacySyntheticEvent.js‎
Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/* globals Event$Init */
11+
12+
/**
13+
 * A bridge event class that extends the W3C Event interface and carries
14+
 * the native event payload. This is used as a compatibility layer during
15+
 * the migration from the legacy SyntheticEvent system to EventTarget-based
16+
 * dispatching.
17+
 */
18+
exportdefaultclassLegacySyntheticEventextendsEvent{
19+
_nativeEvent: {[string]: mixed};
20+
 _propagationStopped: boolean;
21+
22+
constructor(
23+
type: string,
24+
options: Event$Init,
25+
nativeEvent: {[string]: mixed},
26+
){
27+
super(type,options);
28+
this._nativeEvent=nativeEvent;
29+
this._propagationStopped=false;
30+
}
31+
32+
getnativeEvent(): {[string]: mixed}{
33+
returnthis._nativeEvent;
34+
}
35+
36+
stopPropagation(): void{
37+
 super.stopPropagation();
38+
this._propagationStopped=true;
39+
}
40+
41+
stopImmediatePropagation(): void{
42+
 super.stopImmediatePropagation();
43+
this._propagationStopped=true;
44+
}
45+
46+
/**
47+
 * No-op for backward compatibility. The legacy SyntheticEvent system
48+
 * used pooling which required calling persist() to keep the event.
49+
 * With EventTarget-based dispatching, events are never pooled.
50+
 */
51+
persist(): void{
52+
// No-op
53+
}
54+
55+
/**
56+
 * Backward-compatible wrapper for `defaultPrevented`.
57+
 */
58+
isDefaultPrevented(): boolean{
59+
returnthis.defaultPrevented;
60+
}
61+
62+
/**
63+
 * Backward-compatible wrapper. Returns true if stopPropagation()
64+
 * has been called.
65+
 */
66+
isPropagationStopped(): boolean{
67+
returnthis._propagationStopped;
68+
}
69+
}
‎packages/react-native-renderer/src/ReactFabricEventEmitter.js‎
Lines changed: 65 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -28,11 +28,23 @@ import accumulateInto from './legacy-events/accumulateInto';
2828
importgetListenerfrom'./ReactNativeGetListener';
2929
import{runEventsInBatch}from'./legacy-events/EventBatching';
3030

31-
import{RawEventEmitter}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
31+
import{
32+
RawEventEmitter,
33+
ReactNativeViewConfigRegistry,
34+
dispatchTrustedEvent,
35+
setEventInitTimeStamp,
36+
}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
3237
import{getPublicInstance}from'./ReactFiberConfigFabric';
38+
importLegacySyntheticEventfrom'./LegacySyntheticEvent';
39+
import{topLevelTypeToEventName}from'./ReactNativeEventTypeMapping';
40+
import{processResponderEvent}from'./ReactNativeResponder';
41+
import{enableNativeEventTargetEventDispatching}from'./ReactNativeFeatureFlags';
3342

3443
export{getListener,registrationNameModulesasregistrationNames};
3544

45+
const{customBubblingEventTypes, customDirectEventTypes}=
46+
ReactNativeViewConfigRegistry;
47+
3648
/**
3749
 * Allows registered plugins an opportunity to extract events from top-level
3850
 * native browser events.
@@ -47,10 +59,12 @@ function extractPluginEvents(
4759
nativeEventTarget: null|EventTarget,
4860
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
4961
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
50-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
62+
constlegacyPlugins=((plugins: any): Array<
63+
LegacyPluginModule<AnyNativeEvent>,
64+
>);
5165
for(leti=0;i<legacyPlugins.length;i++){
5266
// Not every plugin in the ordering may be loaded at runtime.
53-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
67+
const possiblePlugin =legacyPlugins[i];
5468
if(possiblePlugin){
5569
const extractedEvents =possiblePlugin.extractEvents(
5670
topLevelType,
@@ -84,8 +98,12 @@ function runExtractedPluginEventsInBatch(
8498
exportfunctiondispatchEvent(
8599
target: null|Object,
86100
topLevelType: RNTopLevelEventType,
87-
nativeEvent: AnyNativeEvent,
101+
nativeEventParam: mixed,
88102
){
103+
constnativeEvent: AnyNativeEvent=
104+
nativeEventParam!=null&&typeofnativeEventParam==='object'
105+
 ? (nativeEventParam: any)
106+
 : {};
89107
consttargetFiber=(target: null|Fiber);
90108

91109
leteventTarget=null;
@@ -121,18 +139,52 @@ export function dispatchEvent(
121139
// Note that extracted events are *not* emitted,
122140
// only events that have a 1:1 mapping with a native event, at least for now.
123141
constevent={eventName: topLevelType, nativeEvent};
124-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
125142
RawEventEmitter.emit(topLevelType,event);
126-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
127143
RawEventEmitter.emit('*',event);
128144

129-
// Heritage plugin event system
130-
runExtractedPluginEventsInBatch(
131-
topLevelType,
132-
targetFiber,
133-
nativeEvent,
134-
eventTarget,
135-
);
145+
if(enableNativeEventTargetEventDispatching()){
146+
// Process responder events before normal event dispatch.
147+
// This handles touch negotiation (onStartShouldSetResponder, etc.)
148+
processResponderEvent(topLevelType,targetFiber,nativeEvent);
149+
150+
// New EventTarget-based dispatch path
151+
if(eventTarget!=null){
152+
constbubbleDispatchConfig=customBubblingEventTypes[topLevelType];
153+
constdirectDispatchConfig=customDirectEventTypes[topLevelType];
154+
constbubbles=bubbleDispatchConfig!=null;
155+
156+
// Skip events that are not registered in the view config
157+
if(bubbles||directDispatchConfig!=null){
158+
consteventName=topLevelTypeToEventName(topLevelType);
159+
constoptions={
160+
 bubbles,
161+
cancelable: true,
162+
};
163+
// Preserve the native event timestamp for backwards compatibility.
164+
// The legacy SyntheticEvent system used nativeEvent.timeStamp || nativeEvent.timestamp.
165+
constnativeTimestamp=
166+
nativeEvent.timeStamp??nativeEvent.timestamp;
167+
if(typeofnativeTimestamp==='number'){
168+
setEventInitTimeStamp(options,nativeTimestamp);
169+
}
170+
constsyntheticEvent=newLegacySyntheticEvent(
171+
eventName,
172+
options,
173+
nativeEvent,
174+
);
175+
// $FlowFixMe[incompatible-call]
176+
dispatchTrustedEvent(eventTarget,syntheticEvent);
177+
}
178+
}
179+
}else{
180+
// Heritage plugin event system
181+
runExtractedPluginEventsInBatch(
182+
topLevelType,
183+
targetFiber,
184+
nativeEvent,
185+
eventTarget,
186+
);
187+
}
136188
});
137189
// React Native doesn't use ReactControlledComponent but if it did, here's
138190
// where it would do it.
‎packages/react-native-renderer/src/ReactNativeEventEmitter.js‎
Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -131,10 +131,12 @@ function extractPluginEvents(
131131
nativeEventTarget: null|EventTarget,
132132
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
133133
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
134-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
134+
constlegacyPlugins=((plugins: any): Array<
135+
LegacyPluginModule<AnyNativeEvent>,
136+
>);
135137
for(leti=0;i<legacyPlugins.length;i++){
136138
// Not every plugin in the ordering may be loaded at runtime.
137-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
139+
const possiblePlugin =legacyPlugins[i];
138140
if(possiblePlugin){
139141
const extractedEvents =possiblePlugin.extractEvents(
140142
topLevelType,
‎packages/react-native-renderer/src/ReactNativeEventTypeMapping.js‎
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/**
11+
 * Converts a topLevelType (e.g., "topPress") to a DOM event name (e.g., "press").
12+
 * Strips the "top" prefix and lowercases the result.
13+
 */
14+
exportfunctiontopLevelTypeToEventName(topLevelType: string): string{
15+
constfourthChar=topLevelType.charCodeAt(3);
16+
if(
17+
topLevelType.startsWith('top')&&
18+
fourthChar>=65/* A */&&
19+
fourthChar<=90/* Z */
20+
){
21+
returntopLevelType.slice(3).toLowerCase();
22+
}
23+
returntopLevelType;
24+
}
‎packages/react-native-renderer/src/ReactNativeFeatureFlags.js‎
Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
// These globals are set by React Native (e.g. in setUpDOM.js, setUpTimers.js)
11+
// and provide access to RN's feature flags. We use global functions because we
12+
// don't have another mechanism to pass feature flags from RN to React in OSS.
13+
// Values are lazily evaluated and cached on first access.
14+
15+
let_enableNativeEventTargetEventDispatching: boolean|null=null;
16+
exportfunctionenableNativeEventTargetEventDispatching(): boolean{
17+
if(_enableNativeEventTargetEventDispatching==null){
18+
_enableNativeEventTargetEventDispatching=
19+
typeofRN$isNativeEventTargetEventDispatchingEnabled==='function'&&
20+
RN$isNativeEventTargetEventDispatchingEnabled();
21+
}
22+
return_enableNativeEventTargetEventDispatching;
23+
}
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if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
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})();
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} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
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[react-native-renderer] EventTarget-based event dispatching (#36253) · react/react@5682442 · GitHub
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authored
[react-native-renderer] EventTarget-based event dispatching (#36253)
## Summary
Set up the experiment to migrate event dispatching in the React Native
renderer to be based on the native EventTarget API.
Behind the `enableNativeEventTargetEventDispatching` flag, events are
dispatched through `dispatchTrustedEvent` instead of the legacy plugin
system.
Regular event handler props are NOT registered via addEventListener at
commit time. Instead, a hook on EventTarget
(`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from
`canonical.currentProps` at dispatch time, shifting cost from every
render to only when events fire. The hook is overridden in
ReactNativeElement to look up the prop name via a reverse mapping from
event names (built lazily from the view config registry).
Responder events bypass EventTarget entirely. `negotiateResponder` walks
the fiber tree directly (capture then bubble phase), calling handlers
from `canonical.currentProps` and checking return values inline.
Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers
directly from props and inspect return values — `onResponderGrant`
returning `true` blocks native responder,
`onResponderTerminationRequest` returning `false` refuses termination.
This eliminates all commit-time cost for responder events (no wrappers,
no addEventListener, no `responderWrappers` on canonical).
## How did you test this change?
Flow
Tested e2e in RN using Fantom tests (that will land after this).
1 parent fef12a0 commit 5682442
10 files changed
Lines changed: 775 additions & 16 deletions
File tree
‎.eslintrc.js‎
Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -463,6 +463,7 @@ module.exports = {
463463
globals: {
464464
nativeFabricUIManager: 'readonly',
465465
RN$enableMicrotasksInReact: 'readonly',
466+
RN$isNativeEventTargetEventDispatchingEnabled: 'readonly',
466467
},
467468
},
468469
{
‎packages/react-native-renderer/src/LegacySyntheticEvent.js‎
Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/* globals Event$Init */
11+
12+
/**
13+
 * A bridge event class that extends the W3C Event interface and carries
14+
 * the native event payload. This is used as a compatibility layer during
15+
 * the migration from the legacy SyntheticEvent system to EventTarget-based
16+
 * dispatching.
17+
 */
18+
exportdefaultclassLegacySyntheticEventextendsEvent{
19+
_nativeEvent: {[string]: mixed};
20+
 _propagationStopped: boolean;
21+
22+
constructor(
23+
type: string,
24+
options: Event$Init,
25+
nativeEvent: {[string]: mixed},
26+
){
27+
super(type,options);
28+
this._nativeEvent=nativeEvent;
29+
this._propagationStopped=false;
30+
}
31+
32+
getnativeEvent(): {[string]: mixed}{
33+
returnthis._nativeEvent;
34+
}
35+
36+
stopPropagation(): void{
37+
 super.stopPropagation();
38+
this._propagationStopped=true;
39+
}
40+
41+
stopImmediatePropagation(): void{
42+
 super.stopImmediatePropagation();
43+
this._propagationStopped=true;
44+
}
45+
46+
/**
47+
 * No-op for backward compatibility. The legacy SyntheticEvent system
48+
 * used pooling which required calling persist() to keep the event.
49+
 * With EventTarget-based dispatching, events are never pooled.
50+
 */
51+
persist(): void{
52+
// No-op
53+
}
54+
55+
/**
56+
 * Backward-compatible wrapper for `defaultPrevented`.
57+
 */
58+
isDefaultPrevented(): boolean{
59+
returnthis.defaultPrevented;
60+
}
61+
62+
/**
63+
 * Backward-compatible wrapper. Returns true if stopPropagation()
64+
 * has been called.
65+
 */
66+
isPropagationStopped(): boolean{
67+
returnthis._propagationStopped;
68+
}
69+
}
‎packages/react-native-renderer/src/ReactFabricEventEmitter.js‎
Lines changed: 65 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -28,11 +28,23 @@ import accumulateInto from './legacy-events/accumulateInto';
2828
importgetListenerfrom'./ReactNativeGetListener';
2929
import{runEventsInBatch}from'./legacy-events/EventBatching';
3030

31-
import{RawEventEmitter}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
31+
import{
32+
RawEventEmitter,
33+
ReactNativeViewConfigRegistry,
34+
dispatchTrustedEvent,
35+
setEventInitTimeStamp,
36+
}from'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
3237
import{getPublicInstance}from'./ReactFiberConfigFabric';
38+
importLegacySyntheticEventfrom'./LegacySyntheticEvent';
39+
import{topLevelTypeToEventName}from'./ReactNativeEventTypeMapping';
40+
import{processResponderEvent}from'./ReactNativeResponder';
41+
import{enableNativeEventTargetEventDispatching}from'./ReactNativeFeatureFlags';
3342

3443
export{getListener,registrationNameModulesasregistrationNames};
3544

45+
const{customBubblingEventTypes, customDirectEventTypes}=
46+
ReactNativeViewConfigRegistry;
47+
3648
/**
3749
 * Allows registered plugins an opportunity to extract events from top-level
3850
 * native browser events.
@@ -47,10 +59,12 @@ function extractPluginEvents(
4759
nativeEventTarget: null|EventTarget,
4860
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
4961
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
50-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
62+
constlegacyPlugins=((plugins: any): Array<
63+
LegacyPluginModule<AnyNativeEvent>,
64+
>);
5165
for(leti=0;i<legacyPlugins.length;i++){
5266
// Not every plugin in the ordering may be loaded at runtime.
53-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
67+
const possiblePlugin =legacyPlugins[i];
5468
if(possiblePlugin){
5569
const extractedEvents =possiblePlugin.extractEvents(
5670
topLevelType,
@@ -84,8 +98,12 @@ function runExtractedPluginEventsInBatch(
8498
exportfunctiondispatchEvent(
8599
target: null|Object,
86100
topLevelType: RNTopLevelEventType,
87-
nativeEvent: AnyNativeEvent,
101+
nativeEventParam: mixed,
88102
){
103+
constnativeEvent: AnyNativeEvent=
104+
nativeEventParam!=null&&typeofnativeEventParam==='object'
105+
 ? (nativeEventParam: any)
106+
 : {};
89107
consttargetFiber=(target: null|Fiber);
90108

91109
leteventTarget=null;
@@ -121,18 +139,52 @@ export function dispatchEvent(
121139
// Note that extracted events are *not* emitted,
122140
// only events that have a 1:1 mapping with a native event, at least for now.
123141
constevent={eventName: topLevelType, nativeEvent};
124-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
125142
RawEventEmitter.emit(topLevelType,event);
126-
// $FlowFixMe[class-object-subtyping] found when upgrading Flow
127143
RawEventEmitter.emit('*',event);
128144

129-
// Heritage plugin event system
130-
runExtractedPluginEventsInBatch(
131-
topLevelType,
132-
targetFiber,
133-
nativeEvent,
134-
eventTarget,
135-
);
145+
if(enableNativeEventTargetEventDispatching()){
146+
// Process responder events before normal event dispatch.
147+
// This handles touch negotiation (onStartShouldSetResponder, etc.)
148+
processResponderEvent(topLevelType,targetFiber,nativeEvent);
149+
150+
// New EventTarget-based dispatch path
151+
if(eventTarget!=null){
152+
constbubbleDispatchConfig=customBubblingEventTypes[topLevelType];
153+
constdirectDispatchConfig=customDirectEventTypes[topLevelType];
154+
constbubbles=bubbleDispatchConfig!=null;
155+
156+
// Skip events that are not registered in the view config
157+
if(bubbles||directDispatchConfig!=null){
158+
consteventName=topLevelTypeToEventName(topLevelType);
159+
constoptions={
160+
 bubbles,
161+
cancelable: true,
162+
};
163+
// Preserve the native event timestamp for backwards compatibility.
164+
// The legacy SyntheticEvent system used nativeEvent.timeStamp || nativeEvent.timestamp.
165+
constnativeTimestamp=
166+
nativeEvent.timeStamp??nativeEvent.timestamp;
167+
if(typeofnativeTimestamp==='number'){
168+
setEventInitTimeStamp(options,nativeTimestamp);
169+
}
170+
constsyntheticEvent=newLegacySyntheticEvent(
171+
eventName,
172+
options,
173+
nativeEvent,
174+
);
175+
// $FlowFixMe[incompatible-call]
176+
dispatchTrustedEvent(eventTarget,syntheticEvent);
177+
}
178+
}
179+
}else{
180+
// Heritage plugin event system
181+
runExtractedPluginEventsInBatch(
182+
topLevelType,
183+
targetFiber,
184+
nativeEvent,
185+
eventTarget,
186+
);
187+
}
136188
});
137189
// React Native doesn't use ReactControlledComponent but if it did, here's
138190
// where it would do it.
‎packages/react-native-renderer/src/ReactNativeEventEmitter.js‎
Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -131,10 +131,12 @@ function extractPluginEvents(
131131
nativeEventTarget: null|EventTarget,
132132
): Array<ReactSyntheticEvent>|ReactSyntheticEvent|null{
133133
letevents: Array<ReactSyntheticEvent>|ReactSyntheticEvent|null=null;
134-
constlegacyPlugins=((plugins: any): Array<LegacyPluginModule<Event>>);
134+
constlegacyPlugins=((plugins: any): Array<
135+
LegacyPluginModule<AnyNativeEvent>,
136+
>);
135137
for(leti=0;i<legacyPlugins.length;i++){
136138
// Not every plugin in the ordering may be loaded at runtime.
137-
constpossiblePlugin: LegacyPluginModule<AnyNativeEvent>=legacyPlugins[i];
139+
const possiblePlugin =legacyPlugins[i];
138140
if(possiblePlugin){
139141
const extractedEvents =possiblePlugin.extractEvents(
140142
topLevelType,
‎packages/react-native-renderer/src/ReactNativeEventTypeMapping.js‎
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
/**
11+
 * Converts a topLevelType (e.g., "topPress") to a DOM event name (e.g., "press").
12+
 * Strips the "top" prefix and lowercases the result.
13+
 */
14+
exportfunctiontopLevelTypeToEventName(topLevelType: string): string{
15+
constfourthChar=topLevelType.charCodeAt(3);
16+
if(
17+
topLevelType.startsWith('top')&&
18+
fourthChar>=65/* A */&&
19+
fourthChar<=90/* Z */
20+
){
21+
returntopLevelType.slice(3).toLowerCase();
22+
}
23+
returntopLevelType;
24+
}
‎packages/react-native-renderer/src/ReactNativeFeatureFlags.js‎
Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
 * Copyright (c) Meta Platforms, Inc. and affiliates.
3+
 *
4+
 * This source code is licensed under the MIT license found in the
5+
 * LICENSE file in the root directory of this source tree.
6+
 *
7+
 * @flow
8+
 */
9+
10+
// These globals are set by React Native (e.g. in setUpDOM.js, setUpTimers.js)
11+
// and provide access to RN's feature flags. We use global functions because we
12+
// don't have another mechanism to pass feature flags from RN to React in OSS.
13+
// Values are lazily evaluated and cached on first access.
14+
15+
let_enableNativeEventTargetEventDispatching: boolean|null=null;
16+
exportfunctionenableNativeEventTargetEventDispatching(): boolean{
17+
if(_enableNativeEventTargetEventDispatching==null){
18+
_enableNativeEventTargetEventDispatching=
19+
typeofRN$isNativeEventTargetEventDispatchingEnabled==='function'&&
20+
RN$isNativeEventTargetEventDispatchingEnabled();
21+
}
22+
return_enableNativeEventTargetEventDispatching;
23+
}
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