From e0a08f2ab0856af05e39501006ab856e34506e33 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Mon, 24 Oct 2022 14:56:29 +0200
Subject: [PATCH] LibWeb: Add EventTarget::has_event_listener(FlyString type)

This returns true if the EventTarget has one or more registered
listeners for a given even type.
---
 Userland/Libraries/LibWeb/DOM/EventTarget.cpp | 9 +++++++++
 Userland/Libraries/LibWeb/DOM/EventTarget.h   | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/Userland/Libraries/LibWeb/DOM/EventTarget.cpp b/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
index 82cdcd5aac..f3b35d8a33 100644
--- a/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
+++ b/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
@@ -735,4 +735,13 @@ bool EventTarget::dispatch_event(Event& event)
     return EventDispatcher::dispatch(*this, event);
 }
 
+bool EventTarget::has_event_listener(FlyString const& type) const
+{
+    for (auto& listener : m_event_listener_list) {
+        if (listener->type == type)
+            return true;
+    }
+    return false;
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/DOM/EventTarget.h b/Userland/Libraries/LibWeb/DOM/EventTarget.h
index e3656435cd..cf83892e57 100644
--- a/Userland/Libraries/LibWeb/DOM/EventTarget.h
+++ b/Userland/Libraries/LibWeb/DOM/EventTarget.h
@@ -54,6 +54,8 @@ public:
     WebIDL::CallbackType* event_handler_attribute(FlyString const& name);
     void set_event_handler_attribute(FlyString const& name, WebIDL::CallbackType*);
 
+    bool has_event_listener(FlyString const& type) const;
+
 protected:
     explicit EventTarget(JS::Realm&);