From c4c7c62816bc0d0a2308acf97d0e37494889eed0 Mon Sep 17 00:00:00 2001
From: lin onetwo <linonetwo012@gmail.com>
Date: Tue, 18 Mar 2025 00:50:03 +0800
Subject: [PATCH] feat: prevent adding the same event listener multiple times

---
 core/modules/widgets/widget.js                |  4 ++-
 .../test/tiddlers/tests/test-widget-event.js  | 26 +++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/core/modules/widgets/widget.js b/core/modules/widgets/widget.js
index 36ddd0a37..e2bfb79ca 100755
--- a/core/modules/widgets/widget.js
+++ b/core/modules/widgets/widget.js
@@ -634,7 +634,9 @@ Listener could return a boolean indicating whether to further propagation or not
 */
 Widget.prototype.addEventListener = function(type,handler) {
 	this.eventListeners[type] = this.eventListeners[type] || [];
-	this.eventListeners[type].push(handler);
+	if(this.eventListeners[type].indexOf(handler) === -1) {
+		this.eventListeners[type].push(handler);
+	}
 };
 
 /*
diff --git a/editions/test/tiddlers/tests/test-widget-event.js b/editions/test/tiddlers/tests/test-widget-event.js
index 123679757..b70f5424c 100644
--- a/editions/test/tiddlers/tests/test-widget-event.js
+++ b/editions/test/tiddlers/tests/test-widget-event.js
@@ -193,6 +193,32 @@ describe("Widget Event Listeners", function() {
 		expect(calls).not.toContain("listener1");
 	});
 
+	it("should prevent adding the same event listener multiple times", function() {
+		var calls = 0;
+		var wiki = new $tw.Wiki();
+		var widget = createWidgetNode({type:"widget", text:"text"}, wiki);
+		
+		function listener(e) {
+			calls++;
+			return true;
+		}
+		
+		// Add the same listener multiple times
+		widget.addEventListener("testEvent", listener);
+		widget.addEventListener("testEvent", listener);
+		widget.addEventListener("testEvent", listener);
+		
+		// Dispatch the event
+		var event = {type:"testEvent"};
+		widget.dispatchEvent(event);
+		
+		// The listener should only be called once
+		expect(calls).toBe(1);
+		
+		// Check the internal structure of eventListeners array
+		expect(widget.eventListeners["testEvent"].length).toBe(1);
+	});
+
 });
 
 })();