From 569b1f2de3331938b3cd5e123a49f023c6725fae Mon Sep 17 00:00:00 2001
From: shirakaba <14055146+shirakaba@users.noreply.github.com>
Date: Wed, 21 Dec 2022 16:16:47 +0900
Subject: [PATCH] fix: determine insertion function up-front

---
 packages/core/data/dom-events/dom-event.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/packages/core/data/dom-events/dom-event.ts b/packages/core/data/dom-events/dom-event.ts
index b5cc7fad2..4d7052165 100644
--- a/packages/core/data/dom-events/dom-event.ts
+++ b/packages/core/data/dom-events/dom-event.ts
@@ -208,9 +208,13 @@ export class DOMEvent implements Event {
 			return recycledEventPath;
 		}
 
+		// Determining the function up-front (rather than inside the loop) saves
+		// 50 nanoseconds per dispatchTo() call.
+		const insert = path === 'capture' ? recycledEventPath.unshift.bind(recycledEventPath) : recycledEventPath.push.bind(recycledEventPath);
+
 		let nextResponder = responder.parent;
 		while (nextResponder) {
-			path === 'capture' ? recycledEventPath.unshift(nextResponder) : recycledEventPath.push(nextResponder);
+			insert(nextResponder);
 
 			// TODO: decide whether to walk up from Page to Frame, and whether
 			// to then walk from Frame to Application or something.