fix: declare reset on prototype

shirakaba · shirakaba · commit 13c29db06e2c · 2023-01-21T15:29:33.000+09:00
diff --git a/packages/core/data/dom-events/dom-event.ts b/packages/core/data/dom-events/dom-event.ts
@@ -271,6 +271,20 @@ export class DOMEvent implements Event {
 		this.listenersLive.onMutation = null;
 	}
 
+	/**
+	 * Resets any internal state to allow the event to be redispatched. Call
+	 * this before returning from dispatchTo().
+	 */
+	// Declaring this on the prototype rather than as an arrow function saves
+	// 190 nanoseconds per dispatchTo().
+	private resetForRedispatch() {
+		this.currentTarget = null;
+		this.target = null;
+		this.eventPhase = this.NONE;
+		this.propagationState = EventPropagationState.resume;
+		this.listenersLive = emptyArray;
+		this.listenersLazyCopy = emptyArray;
+	}
 	/**
 	 * Dispatches a synthetic event event to target and returns true if either
 	 * event's cancelable attribute value is false or its preventDefault()
@@ -288,19 +302,6 @@ export class DOMEvent implements Event {
 		// completed the breaking changes to migrate fully to DOMEvents.
 		DOMEvent.unstable_currentEvent = this;
 
-		/**
-		 * Resets any internal state to allow the event to be redispatched. Call
-		 * this before returning.
-		 */
-		const reset = () => {
-			this.currentTarget = null;
-			this.target = null;
-			this.eventPhase = this.NONE;
-			this.propagationState = EventPropagationState.resume;
-			this.listenersLive = emptyArray;
-			this.listenersLazyCopy = emptyArray;
-		};
-
 		// `Observable.removeEventListener` would likely suffice, but grabbing
 		// the static method named `removeEventListener` on the target's class
 		// allows us to be robust to the possiblity of the case of the target
@@ -348,7 +349,7 @@ export class DOMEvent implements Event {
 			});
 
 			if (this.propagationState !== EventPropagationState.resume) {
-				reset();
+				this.resetForRedispatch();
 				return !this.defaultPrevented;
 			}
 		}
@@ -368,15 +369,15 @@ export class DOMEvent implements Event {
 			});
 
 			if (this.propagationState !== EventPropagationState.resume) {
-				reset();
+				this.resetForRedispatch();
 				return !this.defaultPrevented;
 			}
 
 			// If the event doesn't bubble, then, having dispatched it at the
 			// target (the first iteration of this loop) we don't let it
 			// propagate any further.
 			if (!this.bubbles) {
-				reset();
+				this.resetForRedispatch();
 				break;
 			}
 
@@ -393,7 +394,7 @@ export class DOMEvent implements Event {
 			phase: this.BUBBLING_PHASE,
 		});
 
-		reset();
+		this.resetForRedispatch();
 		return !this.defaultPrevented;
 	}
 
