add timer to event handler so we can check whether it was attached du…

…ring the current propagation

src/diff/props.js

@@ -83,7 +83,8 @@ export function setProperty(dom, name, value, oldValue, isSvg) {
 	}
 	// Benchmark for comparison: https://esbench.com/bench/574c954bdb965b9a00965ac6
 	else if (name[0] === 'o' && name[1] === 'n') {
-		useCapture = name !== (name = name.replace(/(PointerCapture)$|Capture$/, '$1'));
+		useCapture =
+			name !== (name = name.replace(/(PointerCapture)$|Capture$/, '$1'));
 
 		// Infer correct casing for DOM built-in events:
 		if (name.toLowerCase() in dom) name = name.toLowerCase().slice(2);
@@ -94,8 +95,11 @@ export function setProperty(dom, name, value, oldValue, isSvg) {
 
 		if (value) {
 			if (!oldValue) {
+				value._attached = Date.now();
 				const handler = useCapture ? eventProxyCapture : eventProxy;
 				dom.addEventListener(name, handler, useCapture);
+			} else {
+				value._attached = oldValue._attached;
 			}
 		} else {
 			const handler = useCapture ? eventProxyCapture : eventProxy;
@@ -151,7 +155,13 @@ export function setProperty(dom, name, value, oldValue, isSvg) {
  * @private
  */
 function eventProxy(e) {
-	return this._listeners[e.type + false](options.event ? options.event(e) : e);
+	const eventHandler = this._listeners[e.type + false];
+	if (!e._dispatched) {
+		e._dispatched = Date.now();
+	} else if (e._dispatched <= eventHandler._attached) {
+		return;
+	}
+	return eventHandler(options.event ? options.event(e) : e);
 }
 
 function eventProxyCapture(e) {