diff --git a/moli-renderer-v8/src/context_bootstrap/event_target_dispatch.rs b/moli-renderer-v8/src/context_bootstrap/event_target_dispatch.rs
index 749c500c21..f3ec578dae 100644
--- a/moli-renderer-v8/src/context_bootstrap/event_target_dispatch.rs
+++ b/moli-renderer-v8/src/context_bootstrap/event_target_dispatch.rs
@@ -4,12 +4,13 @@ use super::{
     clear_event_composed_path, event_initialized, event_internal_bool_flag, event_is_dispatching,
     new_dom_exception_value, set_event_composed_path, set_event_internal_flag, set_event_trusted,
 };
+use crate::event_type::EventType;
 use crate::util::{throw_type_error, v8str};
 
 pub(crate) fn prepare_script_dispatch<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     value: v8::Local<'s, v8::Value>,
-) -> Option<(v8::Local<'s, v8::Object>, String)> {
+) -> Option<(v8::Local<'s, v8::Object>, EventType)> {
     let event = v8::Local::<v8::Object>::try_from(value).ok();
     let Some((event, initialized)) =
         event.and_then(|event| event_initialized(scope, event).map(|flag| (event, flag)))
@@ -31,8 +32,8 @@ pub(crate) fn prepare_script_dispatch<'s>(
     set_event_trusted(scope, event, false);
     let event_type = crate::context_bootstrap::event_backing(scope, event)
         .get(scope, v8str(scope, "type").into())?
-        .to_string(scope)?
-        .to_rust_string_lossy(scope);
+        .to_string(scope)?;
+    let event_type = EventType::from_v8(scope, event_type);
     Some((event, event_type))
 }
 
diff --git a/moli-renderer-v8/src/context_bootstrap/indexed_db/event_target/dispatch.rs b/moli-renderer-v8/src/context_bootstrap/indexed_db/event_target/dispatch.rs
index 6202b2df1c..93dc252cba 100644
--- a/moli-renderer-v8/src/context_bootstrap/indexed_db/event_target/dispatch.rs
+++ b/moli-renderer-v8/src/context_bootstrap/indexed_db/event_target/dispatch.rs
@@ -2,6 +2,7 @@ use super::*;
 use crate::context_bootstrap::{
     EventHandlerType, event_target_dispatch, events, invoke_simple_event_target_listeners,
 };
+use crate::event_type::EventTypeKey;
 use crate::util::get_private_object;
 
 #[derive(Clone, Copy)]
@@ -61,7 +62,7 @@ pub(in crate::context_bootstrap::indexed_db) fn dispatch_idb_event_object<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     event: v8::Local<'s, v8::Object>,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
 ) -> IdbEventDispatchResult {
     let mut result = IdbEventDispatchResult::default();
     let mut path = vec![target];
diff --git a/moli-renderer-v8/src/context_bootstrap/media_queries.rs b/moli-renderer-v8/src/context_bootstrap/media_queries.rs
index ccb2818e43..83c1cdd456 100644
--- a/moli-renderer-v8/src/context_bootstrap/media_queries.rs
+++ b/moli-renderer-v8/src/context_bootstrap/media_queries.rs
@@ -29,6 +29,5 @@ pub(super) use self::events::{
 
 use super::{
     MEDIA_QUERY_LIST_LISTENERS_SLOT, SIMPLE_EVENT_TARGET_ORDERED_HANDLERS_SLOT,
-    SIMPLE_EVENT_TARGET_SLOT, object_property_as_array, object_string_property_defined, v8_string,
-    v8str,
+    SIMPLE_EVENT_TARGET_SLOT, object_string_property_defined, v8str,
 };
diff --git a/moli-renderer-v8/src/context_bootstrap/media_queries/events.rs b/moli-renderer-v8/src/context_bootstrap/media_queries/events.rs
index 393ed1d679..3983e6ee61 100644
--- a/moli-renderer-v8/src/context_bootstrap/media_queries/events.rs
+++ b/moli-renderer-v8/src/context_bootstrap/media_queries/events.rs
@@ -1,7 +1,6 @@
 use super::{
     MEDIA_QUERY_LIST_LISTENERS_SLOT, SIMPLE_EVENT_TARGET_ORDERED_HANDLERS_SLOT,
-    SIMPLE_EVENT_TARGET_SLOT, object_property_as_array, object_string_property_defined, v8_string,
-    v8str,
+    SIMPLE_EVENT_TARGET_SLOT, object_string_property_defined, v8str,
 };
 const SIMPLE_EVENT_TARGET_HANDLER_SLOT_FIELD: &str = "handlerSlot";
 
diff --git a/moli-renderer-v8/src/context_bootstrap/media_queries/events/media_query_list/callbacks.rs b/moli-renderer-v8/src/context_bootstrap/media_queries/events/media_query_list/callbacks.rs
index e4eec173bc..28626b5da5 100644
--- a/moli-renderer-v8/src/context_bootstrap/media_queries/events/media_query_list/callbacks.rs
+++ b/moli-renderer-v8/src/context_bootstrap/media_queries/events/media_query_list/callbacks.rs
@@ -23,7 +23,7 @@ pub(in crate::context_bootstrap) fn media_query_list_add_listener_callback<'s>(
         scope,
         args.this(),
         MEDIA_QUERY_LIST_LISTENERS_SLOT,
-        "change".to_owned(),
+        "change".into(),
         listener,
         webidl::EventListenerOptions::default(),
         None,
diff --git a/moli-renderer-v8/src/context_bootstrap/media_queries/events/simple_event_target/dispatch.rs b/moli-renderer-v8/src/context_bootstrap/media_queries/events/simple_event_target/dispatch.rs
index 4bb62278d2..123bfd02f7 100644
--- a/moli-renderer-v8/src/context_bootstrap/media_queries/events/simple_event_target/dispatch.rs
+++ b/moli-renderer-v8/src/context_bootstrap/media_queries/events/simple_event_target/dispatch.rs
@@ -1,4 +1,5 @@
 use super::*;
+use crate::event_type::EventTypeKey;
 use crate::{
     callback_invocation::{CallbackInvocation, CallbackInvocationOutcome, CallbackInvoker},
     context_bootstrap::events::{
@@ -46,7 +47,7 @@ pub(crate) fn dispatch_simple_event_target_event<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
 ) -> bool {
     dispatch_simple_event_target_event_collecting_errors(
@@ -64,7 +65,7 @@ pub(crate) fn dispatch_simple_event_target_event_collecting_errors<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
     callback_errors: Option<&mut Vec<crate::exception_reporting::V8ExceptionReport>>,
 ) -> SimpleEventDispatchResult {
@@ -84,7 +85,7 @@ pub(crate) fn dispatch_simple_event_target_event_with_original_target<'s>(
     target: v8::Local<'s, v8::Object>,
     original_target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
 ) -> bool {
     dispatch_simple_event_target_event_with_original_target_collecting_errors(
@@ -104,7 +105,7 @@ fn dispatch_simple_event_target_event_with_original_target_collecting_errors<'s>
     target: v8::Local<'s, v8::Object>,
     original_target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
     mut callback_errors: Option<&mut Vec<crate::exception_reporting::V8ExceptionReport>>,
 ) -> SimpleEventDispatchResult {
@@ -117,7 +118,7 @@ fn dispatch_simple_event_target_event_with_original_target_collecting_errors<'s>
             event,
         );
 
-    let error_arguments = if event_type == "error"
+    let error_arguments = if event_type.is_type("error")
         && (crate::web_api_interfaces::WorkerGlobalScope::is_instance(scope, target)
             || crate::web_api_interfaces::Window::is_instance(scope, target))
     {
@@ -136,7 +137,8 @@ fn dispatch_simple_event_target_event_with_original_target_collecting_errors<'s>
     };
     if can_invoke && !simple_event_target_uses_ordered_handlers(scope, target) {
         let handler_name = format!("on{event_type}");
-        if let Some(handler_key) = v8_string(scope, &handler_name)
+        if let Some(event_key) = event_type.to_v8(scope)
+            && let Some(handler_key) = v8::String::concat(scope, v8str(scope, "on"), event_key)
             && let Some(handler_value) = target.get(scope, handler_key.into())
             && let Ok(handler) = v8::Local::<v8::Object>::try_from(handler_value)
             && handler.is_callable()
@@ -223,7 +225,7 @@ pub(crate) fn invoke_simple_event_target_listeners<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
     capture_phase: bool,
     handler_arguments: &[v8::Local<'s, v8::Value>],
@@ -303,7 +305,7 @@ pub(crate) fn invoke_simple_event_target_listeners<'s>(
 
 pub(crate) fn invoke_simple_event_listener<'s>(
     scope: &mut v8::PinScope<'s, '_>,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     callback_name: &str,
     listener: &SimpleObjectEventListenerSnapshot<'s>,
     callback_this: v8::Local<'s, v8::Value>,
@@ -332,7 +334,7 @@ struct SimpleEventCallbackResult {
 #[allow(clippy::too_many_arguments)]
 fn invoke_simple_event_listener_collecting_errors<'s>(
     scope: &mut v8::PinScope<'s, '_>,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     callback_name: &str,
     listener: &SimpleObjectEventListenerSnapshot<'s>,
     callback_this: v8::Local<'s, v8::Value>,
@@ -365,7 +367,7 @@ fn invoke_simple_event_listener_collecting_errors<'s>(
 #[allow(clippy::too_many_arguments)]
 fn invoke_simple_event_callback<'s>(
     scope: &mut v8::PinScope<'s, '_>,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     callback_name: &str,
     callback: v8::Local<'s, v8::Object>,
     relevant_context: v8::Local<'s, v8::Context>,
@@ -417,7 +419,7 @@ fn simple_event_target_interface_name<'s>(
 #[allow(clippy::too_many_arguments)]
 fn invoke_simple_event_callback_with_invocation<'s>(
     scope: &mut v8::PinScope<'s, '_>,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     callback_name: &str,
     callback_target: v8::Local<'s, v8::Value>,
     relevant_context: v8::Local<'s, v8::Context>,
diff --git a/moli-renderer-v8/src/context_bootstrap/media_queries/events/simple_event_target/listeners.rs b/moli-renderer-v8/src/context_bootstrap/media_queries/events/simple_event_target/listeners.rs
index f06c228723..c26f8c6072 100644
--- a/moli-renderer-v8/src/context_bootstrap/media_queries/events/simple_event_target/listeners.rs
+++ b/moli-renderer-v8/src/context_bootstrap/media_queries/events/simple_event_target/listeners.rs
@@ -4,6 +4,7 @@ use crate::callback_invocation::CallbackInvocation;
 use crate::event_listener_args::{
     AddEventListenerArgs, RemoveEventListenerArgs, parse_listener_args,
 };
+use crate::event_type::{EventType, EventTypeKey};
 use crate::native_bridge::{WindowExecutionContextIdentity, lightweight_popup_id_from_window};
 use crate::util::{
     context_host_ptr_from_global_bridge, get_private_object, get_private_value,
@@ -128,7 +129,7 @@ impl<'s> SimpleObjectEventListenerSnapshot<'s> {
         scope: &mut v8::PinScope<'s, '_>,
         target: v8::Local<'s, v8::Object>,
         slot_name: &str,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<Self> {
         let listener = self.resolve_callback(scope, target, slot_name, event_type)?;
         if listener.once {
@@ -149,7 +150,7 @@ impl<'s> SimpleObjectEventListenerSnapshot<'s> {
         scope: &mut v8::PinScope<'s, '_>,
         target: v8::Local<'s, v8::Object>,
         slot_name: &str,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<Self> {
         // Removing and re-adding the same callback creates a different entry.
         // The removed entry must stay inactive in an existing dispatch snapshot.
@@ -262,7 +263,7 @@ pub(crate) fn simple_object_event_target_register_webidl_listener<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: String,
+    event_type: EventType,
     listener: webidl::WebIdlCallbackInterface,
     options: webidl::EventListenerOptions,
     signal: Option<ResolvedAbortSignal<'s>>,
@@ -278,7 +279,7 @@ fn simple_object_event_target_register_resolved_listener<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: String,
+    event_type: EventType,
     listener: SimpleObjectResolvedEventListener<'s>,
     options: webidl::EventListenerOptions,
     signal: Option<ResolvedAbortSignal<'s>>,
@@ -339,7 +340,7 @@ fn simple_object_event_target_register_resolved_listener<'s>(
             options.capture,
         );
     }
-    if event_type == "message" {
+    if event_type.is_type("message") {
         crate::context_bootstrap::flush_pending_worker_messages_for_listener(scope, target);
     }
 }
@@ -393,7 +394,7 @@ fn simple_object_abort_remove_listener_callback<'s>(
     let Some(event_type) = data
         .get(scope, v8str(scope, "type").into())
         .and_then(|value| value.to_string(scope))
-        .map(|value| value.to_rust_string_lossy(scope))
+        .map(|value| EventType::from_v8(scope, value))
     else {
         return;
     };
@@ -429,14 +430,14 @@ fn register_simple_object_abort_listener<'s>(
     target: v8::Local<'s, v8::Object>,
     entry: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     listener: v8::Local<'s, v8::Value>,
     capture: bool,
 ) -> bool {
     let Some(slot_value) = v8_string(scope, slot_name) else {
         return false;
     };
-    let Some(event_type_value) = v8_string(scope, event_type) else {
+    let Some(event_type_value) = event_type.to_v8(scope) else {
         return false;
     };
     let data = SimpleObjectAbortListenerDataDeclaration::new(
@@ -499,22 +500,21 @@ pub(in crate::context_bootstrap::media_queries::events::simple_event_target) fn
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     create: bool,
 ) -> Option<v8::Local<'s, v8::Array>> {
     let registry = simple_object_event_listener_registry(scope, target, slot_name, create)?;
-    if let Some(listeners) = object_property_as_array(scope, registry, event_type) {
+    if let Some(listeners) = registry
+        .get(scope, event_type.to_v8(scope)?.into())
+        .and_then(|value| v8::Local::<v8::Array>::try_from(value).ok())
+    {
         return Some(listeners);
     }
     if !create {
         return None;
     }
     let listeners = v8::Array::new(scope, 0);
-    let _ = registry.set(
-        scope,
-        v8_string(scope, event_type)?.into(),
-        listeners.into(),
-    );
+    let _ = registry.set(scope, event_type.to_v8(scope)?.into(), listeners.into());
     Some(listeners)
 }
 
@@ -522,7 +522,7 @@ pub(crate) fn simple_object_event_listeners_snapshot<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
 ) -> Vec<SimpleObjectEventListenerSnapshot<'s>> {
     let Some(listeners) =
         simple_object_event_listener_array(scope, target, slot_name, event_type, false)
@@ -558,7 +558,7 @@ pub(crate) fn simple_object_has_event_listeners<'s>(
         let Some(event_type) = event_types
             .get_index(scope, index)
             .and_then(|value| value.to_string(scope))
-            .map(|value| value.to_rust_string_lossy(scope))
+            .map(|value| EventType::from_v8(scope, value))
         else {
             continue;
         };
@@ -589,7 +589,7 @@ pub(crate) fn simple_event_target_inspector_listener_snapshots<'s>(
         let Some(event_type) = event_types
             .get_index(scope, index)
             .and_then(|value| value.to_string(scope))
-            .map(|value| value.to_rust_string_lossy(scope))
+            .map(|value| EventType::from_v8(scope, value))
         else {
             continue;
         };
@@ -609,7 +609,7 @@ pub(crate) fn simple_event_target_inspector_listener_snapshots<'s>(
                 listener.original
             };
             snapshots.push(SimpleObjectEventListenerInspectorSnapshot {
-                event_type: event_type.clone(),
+                event_type: event_type.as_str_lossy().to_owned(),
                 original,
                 callback,
                 relevant_context: listener.relevant_context,
@@ -627,7 +627,7 @@ pub(crate) fn simple_object_event_set_ordered_handler<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     handler_slot_name: &'static str,
     active: bool,
 ) {
@@ -670,7 +670,7 @@ pub(crate) fn simple_object_event_set_ordered_handler<'s>(
         let _ = next.set_index(scope, next.length(), candidate);
     }
     if let Some(registry) = simple_object_event_listener_registry(scope, target, slot_name, false)
-        && let Some(key) = v8_string(scope, event_type)
+        && let Some(key) = event_type.to_v8(scope)
     {
         let _ = registry.set(scope, key.into(), next.into());
         if next.length() == 0 {
@@ -696,7 +696,7 @@ pub(crate) fn simple_object_event_activate_uncompiled_handler<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     handler_slot_name: &'static str,
 ) {
     set_simple_object_event_ordered_handler_callback(
@@ -713,7 +713,7 @@ fn set_simple_object_event_ordered_handler_callback<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     handler_slot_name: &'static str,
     callback: Option<v8::Local<'s, v8::Object>>,
 ) {
@@ -800,7 +800,7 @@ pub(crate) fn simple_object_event_remove_listener_value_for_type<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     listener: v8::Local<'s, v8::Value>,
     capture: bool,
 ) {
@@ -808,7 +808,11 @@ pub(crate) fn simple_object_event_remove_listener_value_for_type<'s>(
     else {
         return;
     };
-    let Some(current) = object_property_as_array(scope, registry, event_type) else {
+    let Some(current) = event_type
+        .to_v8(scope)
+        .and_then(|key| registry.get(scope, key.into()))
+        .and_then(|value| v8::Local::<v8::Array>::try_from(value).ok())
+    else {
         return;
     };
     let next = v8::Array::new(scope, 0);
@@ -825,7 +829,7 @@ pub(crate) fn simple_object_event_remove_listener_value_for_type<'s>(
         }
         let _ = next.set_index(scope, next.length(), candidate);
     }
-    if let Some(key) = v8_string(scope, event_type) {
+    if let Some(key) = event_type.to_v8(scope) {
         let _ = registry.set(scope, key.into(), next.into());
         if next.length() == 0 {
             remove_simple_object_event_type_order(scope, registry, event_type);
@@ -899,7 +903,7 @@ fn ensure_simple_object_event_type_order<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
 ) {
     let Some(registry) = simple_object_event_listener_registry(scope, target, slot_name, false)
     else {
@@ -908,36 +912,40 @@ fn ensure_simple_object_event_type_order<'s>(
     let Some(order) = simple_object_event_type_order(scope, registry, true) else {
         return;
     };
+    let Some(key) = event_type.to_v8(scope) else {
+        return;
+    };
     for index in 0..order.length() {
         if order
             .get_index(scope, index)
             .and_then(|value| value.to_string(scope))
-            .is_some_and(|value| value.to_rust_string_lossy(scope) == event_type)
+            .is_some_and(|value| value.strict_equals(key.into()))
         {
             return;
         }
     }
-    if let Some(event_type) = v8_string(scope, event_type) {
-        let _ = order.set_index(scope, order.length(), event_type.into());
-    }
+    let _ = order.set_index(scope, order.length(), key.into());
 }
 
 fn remove_simple_object_event_type_order<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     registry: v8::Local<'s, v8::Object>,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
 ) {
     let Some(order) = simple_object_event_type_order(scope, registry, false) else {
         return;
     };
     let next = v8::Array::new(scope, 0);
+    let Some(key) = event_type.to_v8(scope) else {
+        return;
+    };
     for index in 0..order.length() {
         let Some(candidate) = order.get_index(scope, index) else {
             continue;
         };
         if candidate
             .to_string(scope)
-            .is_some_and(|value| value.to_rust_string_lossy(scope) == event_type)
+            .is_some_and(|value| value.strict_equals(key.into()))
         {
             continue;
         }
@@ -1129,7 +1137,7 @@ fn simple_object_event_listener_entry_registered<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     target: v8::Local<'s, v8::Object>,
     slot_name: &str,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     entry: v8::Local<'s, v8::Object>,
 ) -> bool {
     let Some(listeners) =
diff --git a/moli-renderer-v8/src/context_bootstrap/shared/object.rs b/moli-renderer-v8/src/context_bootstrap/shared/object.rs
index 81d5adb776..a2b5d8dd77 100644
--- a/moli-renderer-v8/src/context_bootstrap/shared/object.rs
+++ b/moli-renderer-v8/src/context_bootstrap/shared/object.rs
@@ -3,8 +3,8 @@ pub(in crate::context_bootstrap) use crate::util::{
     array_contains_strict, array_push_value, get_own_static_property, get_private_value,
     global_constructor_object, global_constructor_prototype, object_bool_property,
     object_defined_string_property as object_string_property_defined,
-    object_own_static_bool_property, object_property_as_array, object_property_as_object,
-    object_string_property, set_private_value,
+    object_own_static_bool_property, object_property_as_object, object_string_property,
+    set_private_value,
 };
 
 pub(in crate::context_bootstrap) fn global_queue_array<'s>(
diff --git a/moli-renderer-v8/src/context_bootstrap/shared_event_targets.rs b/moli-renderer-v8/src/context_bootstrap/shared_event_targets.rs
index 9deee49511..da4480a296 100644
--- a/moli-renderer-v8/src/context_bootstrap/shared_event_targets.rs
+++ b/moli-renderer-v8/src/context_bootstrap/shared_event_targets.rs
@@ -152,6 +152,11 @@ fn handler_setter<'s>(
         return;
     };
     media_queries::simple_object_event_set_ordered_handler(
-        scope, target, &listeners, event_type, slot, active,
+        scope,
+        target,
+        &listeners,
+        *event_type,
+        slot,
+        active,
     );
 }
diff --git a/moli-renderer-v8/src/document_runtime/events.rs b/moli-renderer-v8/src/document_runtime/events.rs
index 32bacc89aa..d13ff6a10a 100644
--- a/moli-renderer-v8/src/document_runtime/events.rs
+++ b/moli-renderer-v8/src/document_runtime/events.rs
@@ -1,4 +1,5 @@
 use super::*;
+use crate::event_type::EventTypeKey;
 use crate::host::HostTimerOwner;
 use crate::host::PublicEventDispatchResult;
 use crate::script_provenance::CompiledStringProvenance;
@@ -388,7 +389,7 @@ impl DocumentRuntime {
     pub(crate) fn event_listener_callback_ids(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         capture: bool,
     ) -> Vec<crate::native_bridge::EventCallbackId> {
         self.events
@@ -405,7 +406,7 @@ impl DocumentRuntime {
     pub(crate) fn insert_event_listener(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         registration: crate::host::EventListenerRegistration,
     ) {
         if !self
@@ -427,7 +428,7 @@ impl DocumentRuntime {
     pub(crate) fn remove_event_listener_by_id(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: crate::native_bridge::EventCallbackId,
         capture: bool,
     ) -> bool {
@@ -445,7 +446,7 @@ impl DocumentRuntime {
     pub(crate) fn set_event_handler_property(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: Option<crate::native_bridge::EventCallbackId>,
     ) -> Option<crate::native_bridge::EventCallbackId> {
         self.events
@@ -455,7 +456,7 @@ impl DocumentRuntime {
     pub(crate) fn set_compiled_event_handler_property(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: Option<crate::native_bridge::EventCallbackId>,
     ) -> Option<crate::native_bridge::EventCallbackId> {
         self.events
@@ -465,7 +466,7 @@ impl DocumentRuntime {
     pub(crate) fn set_event_handler_content_attribute(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         owner: Option<DomHandle>,
     ) -> Option<crate::native_bridge::EventCallbackId> {
         self.events
@@ -527,7 +528,7 @@ impl DocumentRuntime {
     pub(crate) fn uncompiled_event_handler_content_attribute_owner(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<DomHandle> {
         self.events
             .uncompiled_event_handler_content_attribute_owner(target, event_type)
@@ -536,13 +537,17 @@ impl DocumentRuntime {
     pub(crate) fn event_handler_property_callback_id(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<Option<crate::native_bridge::EventCallbackId>> {
         self.events
             .event_handler_property_callback_id(target, event_type)
     }
 
-    pub(crate) fn has_event_listener(&self, target: EventTargetHandle, event_type: &str) -> bool {
+    pub(crate) fn has_event_listener(
+        &self,
+        target: EventTargetHandle,
+        event_type: &(impl EventTypeKey + ?Sized),
+    ) -> bool {
         self.events.has_listener(target, event_type)
     }
 
diff --git a/moli-renderer-v8/src/event_listener_args.rs b/moli-renderer-v8/src/event_listener_args.rs
index 5a801a4ee4..3552f66048 100644
--- a/moli-renderer-v8/src/event_listener_args.rs
+++ b/moli-renderer-v8/src/event_listener_args.rs
@@ -1,6 +1,7 @@
 //! The shared EventTarget argument boundary, before target-specific mutation.
 
 use crate::abort_signal_route::{ResolvedAbortSignal, event_listener_signal_from_options_value};
+use crate::event_type::EventType;
 use crate::webidl;
 
 pub(crate) fn parse_listener_args<'s, T: webidl::WebIdlArguments<'s>>(
@@ -26,8 +27,8 @@ pub(crate) fn parse_listener_args<'s, T: webidl::WebIdlArguments<'s>>(
 #[derive(webidl::WebIdlArgs)]
 #[webidl(prefix = "EventTarget.addEventListener")]
 pub(crate) struct AddEventListenerArgs<'s> {
-    #[webidl(required, name = "type")]
-    pub(crate) event_type: String,
+    #[webidl(required, name = "type", converter = "raw")]
+    pub(crate) event_type: EventType,
     #[webidl(required, converter = "callback_interface", nullable)]
     pub(crate) listener: Option<webidl::WebIdlCallbackInterface>,
     #[webidl(with = add_event_listener_options)]
@@ -37,8 +38,8 @@ pub(crate) struct AddEventListenerArgs<'s> {
 #[derive(webidl::WebIdlArgs)]
 #[webidl(prefix = "EventTarget.removeEventListener")]
 pub(crate) struct RemoveEventListenerArgs {
-    #[webidl(required, name = "type")]
-    pub(crate) event_type: String,
+    #[webidl(required, name = "type", converter = "raw")]
+    pub(crate) event_type: EventType,
     #[webidl(required, converter = "callback_interface", nullable)]
     pub(crate) listener: Option<webidl::WebIdlCallbackInterface>,
     #[webidl(with = webidl::event_listener_options)]
diff --git a/moli-renderer-v8/src/event_type.rs b/moli-renderer-v8/src/event_type.rs
new file mode 100644
index 0000000000..70d86e9b0e
--- /dev/null
+++ b/moli-renderer-v8/src/event_type.rs
@@ -0,0 +1,139 @@
+//! Event type identity is a DOMString, including unpaired UTF-16 surrogates.
+
+use std::{
+    fmt,
+    hash::{Hash, Hasher},
+};
+
+use crate::{dom::native::DomStringValue, util, webidl};
+use indexmap::Equivalent;
+
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub(crate) struct EventType(DomStringValue);
+
+impl EventType {
+    pub(crate) fn from_v8(scope: &v8::PinScope<'_, '_>, value: v8::Local<'_, v8::String>) -> Self {
+        let mut units = vec![0; value.length()];
+        value.write_v2(scope, 0, &mut units, v8::WriteFlags::empty());
+        Self(DomStringValue::from_utf16(&units))
+    }
+}
+
+impl Hash for EventType {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        // Scalar strings share str's hash so native names can be queried without
+        // allocating. Surrogate-bearing keys retain their original identity.
+        self.0.as_str_lossy().hash(state);
+        if self.0.as_str().is_none() {
+            self.0.utf16_units().hash(state);
+        }
+    }
+}
+
+impl fmt::Display for EventType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.0.as_str_lossy())
+    }
+}
+
+impl From<&str> for EventType {
+    fn from(value: &str) -> Self {
+        Self(value.into())
+    }
+}
+
+impl<'s> webidl::WebIdlConverter<'s> for EventType {
+    type Options = webidl::StringOptions;
+
+    fn convert(
+        scope: &mut v8::PinScope<'s, '_>,
+        value: v8::Local<'s, v8::Value>,
+        context: webidl::Context,
+        options: &Self::Options,
+    ) -> Result<Self, webidl::WebIdlError> {
+        webidl::DomString16::convert(scope, value, context, options)
+            .map(|value| Self(DomStringValue::from_utf16(&value.0)))
+    }
+}
+
+/// A borrowed native name or an already-converted JS event type.
+pub(crate) trait EventTypeKey: Hash + Equivalent<EventType> + fmt::Display {
+    fn to_event_type(&self) -> EventType;
+    fn as_str_lossy(&self) -> &str;
+    fn as_str(&self) -> Option<&str>;
+    fn is_type(&self, name: &str) -> bool;
+    fn to_v8<'s>(&self, scope: &v8::PinScope<'s, '_>) -> Option<v8::Local<'s, v8::String>>;
+}
+
+impl EventTypeKey for EventType {
+    fn to_event_type(&self) -> EventType {
+        self.clone()
+    }
+    fn as_str_lossy(&self) -> &str {
+        self.0.as_str_lossy()
+    }
+    fn as_str(&self) -> Option<&str> {
+        self.0.as_str()
+    }
+    fn is_type(&self, name: &str) -> bool {
+        self.0.as_str() == Some(name)
+    }
+    fn to_v8<'s>(&self, scope: &v8::PinScope<'s, '_>) -> Option<v8::Local<'s, v8::String>> {
+        match self.0.as_str() {
+            Some(value) => util::v8_string(scope, value),
+            None => v8::String::new_from_two_byte(
+                scope,
+                &self.0.utf16_units(),
+                v8::NewStringType::Normal,
+            ),
+        }
+    }
+}
+
+impl Equivalent<EventType> for str {
+    fn equivalent(&self, other: &EventType) -> bool {
+        other.is_type(self)
+    }
+}
+
+impl EventTypeKey for str {
+    fn to_event_type(&self) -> EventType {
+        self.into()
+    }
+    fn as_str_lossy(&self) -> &str {
+        self
+    }
+    fn as_str(&self) -> Option<&str> {
+        Some(self)
+    }
+    fn is_type(&self, name: &str) -> bool {
+        self == name
+    }
+    fn to_v8<'s>(&self, scope: &v8::PinScope<'s, '_>) -> Option<v8::Local<'s, v8::String>> {
+        util::v8_string(scope, self)
+    }
+}
+
+impl Equivalent<EventType> for String {
+    fn equivalent(&self, other: &EventType) -> bool {
+        self.as_str().equivalent(other)
+    }
+}
+
+impl EventTypeKey for String {
+    fn to_event_type(&self) -> EventType {
+        self.as_str().into()
+    }
+    fn as_str_lossy(&self) -> &str {
+        self
+    }
+    fn as_str(&self) -> Option<&str> {
+        Some(self)
+    }
+    fn is_type(&self, name: &str) -> bool {
+        self == name
+    }
+    fn to_v8<'s>(&self, scope: &v8::PinScope<'s, '_>) -> Option<v8::Local<'s, v8::String>> {
+        util::v8_string(scope, self)
+    }
+}
diff --git a/moli-renderer-v8/src/host/events.rs b/moli-renderer-v8/src/host/events.rs
index a542cc23a6..602e20929a 100644
--- a/moli-renderer-v8/src/host/events.rs
+++ b/moli-renderer-v8/src/host/events.rs
@@ -1,4 +1,5 @@
 use super::*;
+use crate::event_type::{EventType, EventTypeKey};
 use crate::{
     context_bootstrap::{
         CHILD_BROWSING_CONTEXT_HANDLE_SLOT, EventHandlerType,
@@ -158,8 +159,9 @@ impl EventDispatchEntry {
 pub(crate) fn event_handler_content_attribute_owner(
     runtime: &DocumentRuntime,
     target: EventTargetHandle,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
 ) -> Option<DomHandle> {
+    let event_type = event_type.as_str()?;
     let attribute_name =
         crate::native_bridge::element::event_handler_content_attribute_name(event_type)?;
     let handle = match target {
@@ -195,9 +197,10 @@ pub(crate) fn event_handler_content_attribute_owner(
 }
 
 pub(crate) struct HostEventTargetRegistry {
-    listeners: HashMap<EventTargetHandle, HashMap<String, Vec<EventListenerEntry>>>,
-    handler_properties: HashMap<EventTargetHandle, HashMap<String, EventHandlerPropertyEntry>>,
-    event_type_registration_ids: HashMap<EventTargetHandle, HashMap<String, u64>>,
+    listeners: HashMap<EventTargetHandle, indexmap::IndexMap<EventType, Vec<EventListenerEntry>>>,
+    handler_properties:
+        HashMap<EventTargetHandle, indexmap::IndexMap<EventType, EventHandlerPropertyEntry>>,
+    event_type_registration_ids: HashMap<EventTargetHandle, indexmap::IndexMap<EventType, u64>>,
     next_listener_id: u64,
 }
 
@@ -235,7 +238,7 @@ pub(crate) fn invoke_prepared_event_callback<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     host_ptr: *mut JsContextHost,
     invocation_target_in_shadow_tree: bool,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     callback_name: &str,
     callback: crate::native_bridge::PreparedEventCallback,
     target: EventTargetHandle,
@@ -261,7 +264,7 @@ pub(crate) fn invoke_prepared_event_callback<'s>(
 fn invoke_prepared_event_callback_with_receiver<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     host_ptr: *mut JsContextHost,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     callback_name: &str,
     callback: crate::native_bridge::PreparedEventCallback,
     receiver: v8::Local<'s, v8::Value>,
@@ -303,7 +306,7 @@ pub(crate) fn invoke_prepared_before_unload_event_handler<'s>(
     host_ptr: *mut JsContextHost,
     target: EventTargetHandle,
     invocation_target_in_shadow_tree: bool,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     callback_name: &str,
     callback: crate::native_bridge::PreparedEventCallback,
     event: v8::Local<'s, v8::Object>,
@@ -393,11 +396,12 @@ fn invoke_event_handler_property<'s>(
     target: EventTargetHandle,
     invocation_target_in_shadow_tree: bool,
     target_object: v8::Local<'s, v8::Object>,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
 ) {
-    let Some(handler_name) =
-        crate::native_bridge::element::event_handler_content_attribute_name(event_type)
+    let Some(handler_name) = event_type
+        .as_str()
+        .and_then(crate::native_bridge::element::event_handler_content_attribute_name)
     else {
         return;
     };
@@ -481,7 +485,7 @@ fn invoke_registered_event_handler<'s>(
     host_ptr: *mut JsContextHost,
     target: EventTargetHandle,
     invocation_target_in_shadow_tree: bool,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
     callback_id: crate::native_bridge::EventCallbackId,
 ) {
@@ -492,7 +496,7 @@ fn invoke_registered_event_handler<'s>(
 
     let timing_started = moli_trace::cdp_nav_timing_enabled().then(Instant::now);
     if target == EventTargetHandle::Window
-        && event_type == "error"
+        && event_type.is_type("error")
         && let Some(arguments) = error_event_handler_arguments(scope, event)
     {
         let returned = invoke_prepared_event_callback(
@@ -519,7 +523,7 @@ fn invoke_registered_event_handler<'s>(
             tracing::info!(
                 target: "moli_cdp_nav_timing",
                 stage = "event_handler_property_invoked",
-                event_type,
+                event_type = %event_type,
                 handler_name,
                 ?target,
                 elapsed_ms = timing_started.elapsed().as_millis(),
@@ -528,7 +532,7 @@ fn invoke_registered_event_handler<'s>(
         return;
     }
 
-    if event_type == "beforeunload" {
+    if event_type.is_type("beforeunload") {
         invoke_prepared_before_unload_event_handler(
             scope,
             host_ptr,
@@ -543,7 +547,7 @@ fn invoke_registered_event_handler<'s>(
             tracing::info!(
                 target: "moli_cdp_nav_timing",
                 stage = "event_handler_property_invoked",
-                event_type,
+                event_type = %event_type,
                 handler_name,
                 ?target,
                 elapsed_ms = timing_started.elapsed().as_millis(),
@@ -571,7 +575,7 @@ fn invoke_registered_event_handler<'s>(
         tracing::info!(
             target: "moli_cdp_nav_timing",
             stage = "event_handler_property_invoked",
-            event_type,
+            event_type = %event_type,
             handler_name,
             ?target,
             elapsed_ms = timing_started.elapsed().as_millis(),
@@ -585,7 +589,7 @@ fn call_event_target_listeners_filtered<'s>(
     host_ptr: *mut JsContextHost,
     target: EventTargetHandle,
     invocation_target_in_shadow_tree: bool,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
     capture_only: bool,
     at_target: bool,
@@ -641,7 +645,7 @@ fn event_target_is_current(host_ptr: *mut JsContextHost, target: EventTargetHand
 pub(crate) fn report_event_listener_exception<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     host_ptr: *mut JsContextHost,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     handler: v8::Local<'s, v8::Function>,
     report: &V8ExceptionReport,
 ) {
@@ -662,7 +666,7 @@ pub(crate) fn report_event_listener_exception<'s>(
 pub(crate) fn report_event_callback_exception<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     host_ptr: *mut JsContextHost,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     relevant_identity: Option<crate::native_bridge::WindowExecutionContextIdentity>,
     child_handle: Option<DomHandle>,
     report: &V8ExceptionReport,
@@ -689,7 +693,7 @@ pub(crate) fn report_event_callback_exception<'s>(
                 return;
             };
             Some(reporting_scope)
-        } else if event_type == "error" {
+        } else if event_type.is_type("error") {
             return;
         } else {
             None
@@ -869,7 +873,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn set_event_handler_property(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: Option<crate::native_bridge::EventCallbackId>,
     ) -> Option<crate::native_bridge::EventCallbackId> {
         let existing_listener_id = self
@@ -886,7 +890,7 @@ impl HostEventTargetRegistry {
             .map(EventHandlerPropertyState::Callback)
             .unwrap_or(EventHandlerPropertyState::Null);
         let previous = self.handler_properties.entry(target).or_default().insert(
-            event_type.to_owned(),
+            event_type.to_event_type(),
             EventHandlerPropertyEntry { listener_id, state },
         );
         let previous_callback = previous.and_then(event_handler_callback_id);
@@ -899,7 +903,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn set_compiled_event_handler_property(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: Option<crate::native_bridge::EventCallbackId>,
     ) -> Option<crate::native_bridge::EventCallbackId> {
         let listener_id = self
@@ -913,7 +917,7 @@ impl HostEventTargetRegistry {
             .map(EventHandlerPropertyState::Callback)
             .unwrap_or(EventHandlerPropertyState::Null);
         let previous = self.handler_properties.entry(target).or_default().insert(
-            event_type.to_owned(),
+            event_type.to_event_type(),
             EventHandlerPropertyEntry {
                 listener_id: Some(listener_id),
                 state,
@@ -925,18 +929,18 @@ impl HostEventTargetRegistry {
     pub(crate) fn set_event_handler_content_attribute(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         owner: Option<DomHandle>,
     ) -> Option<crate::native_bridge::EventCallbackId> {
         let Some(owner) = owner else {
             let removed = self
                 .handler_properties
                 .get_mut(&target)
-                .and_then(|handlers| handlers.remove(event_type));
+                .and_then(|handlers| handlers.shift_remove(event_type));
             let remove_target = self
                 .handler_properties
                 .get(&target)
-                .is_some_and(HashMap::is_empty);
+                .is_some_and(indexmap::IndexMap::is_empty);
             if remove_target {
                 self.handler_properties.remove(&target);
             }
@@ -952,7 +956,7 @@ impl HostEventTargetRegistry {
             .unwrap_or_else(|| self.allocate_listener_id());
         self.ensure_event_type_registration_id(target, event_type, listener_id);
         let previous = self.handler_properties.entry(target).or_default().insert(
-            event_type.to_owned(),
+            event_type.to_event_type(),
             EventHandlerPropertyEntry {
                 listener_id: Some(listener_id),
                 state: EventHandlerPropertyState::Uncompiled(owner),
@@ -964,7 +968,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn has_event_handler_property_entry(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> bool {
         self.handler_properties
             .get(&target)
@@ -974,7 +978,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn ensure_event_handler_content_attribute(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         owner: Option<DomHandle>,
     ) {
         if let Some(owner) = owner
@@ -991,7 +995,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn uncompiled_event_handler_content_attribute_owner(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<DomHandle> {
         match &self
             .handler_properties
@@ -1007,7 +1011,7 @@ impl HostEventTargetRegistry {
     fn event_handler_property_value(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<EventHandlerPropertyValue> {
         match &self
             .handler_properties
@@ -1026,7 +1030,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn event_handler_property_callback_id(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<Option<crate::native_bridge::EventCallbackId>> {
         match &self
             .handler_properties
@@ -1043,7 +1047,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn listener_callback_ids(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         capture: bool,
     ) -> Vec<crate::native_bridge::EventCallbackId> {
         self.listeners
@@ -1071,7 +1075,7 @@ impl HostEventTargetRegistry {
                         event_type_registration_id,
                         EventListenerInspectorSnapshot {
                             registration_id: entry.id,
-                            event_type: event_type.clone(),
+                            event_type: event_type.as_str_lossy().to_owned(),
                             callback_id: entry.callback_id,
                             capture: entry.capture,
                             once: entry.once,
@@ -1094,7 +1098,7 @@ impl HostEventTargetRegistry {
                         .unwrap_or(registration_id),
                     EventListenerInspectorSnapshot {
                         registration_id,
-                        event_type: event_type.clone(),
+                        event_type: event_type.as_str_lossy().to_owned(),
                         callback_id,
                         capture: false,
                         once: false,
@@ -1115,7 +1119,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn insert_listener(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         registration: EventListenerRegistration,
     ) {
         let id = self.allocate_listener_id();
@@ -1124,14 +1128,14 @@ impl HostEventTargetRegistry {
             .listeners
             .entry(target)
             .or_default()
-            .entry(event_type.to_owned())
+            .entry(event_type.to_event_type())
             .or_default();
         if moli_trace::cdp_nav_timing_enabled() {
             tracing::info!(
                 target: "moli_cdp_nav_timing",
                 stage = "event_listener_registered",
                 id,
-                event_type,
+                event_type = %event_type,
                 ?target,
                 capture = registration.capture,
                 passive = registration.passive,
@@ -1160,7 +1164,7 @@ impl HostEventTargetRegistry {
     pub(crate) fn remove_listener_by_id(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: crate::native_bridge::EventCallbackId,
         capture: bool,
     ) -> bool {
@@ -1174,7 +1178,7 @@ impl HostEventTargetRegistry {
         entries.retain(|entry| entry.callback_id != callback_id || entry.capture != capture);
         let removed = entries.len() != before;
         if entries.is_empty() {
-            target_listeners.remove(event_type);
+            target_listeners.shift_remove(event_type);
         }
         if target_listeners.is_empty() {
             self.listeners.remove(&target);
@@ -1212,7 +1216,11 @@ impl HostEventTargetRegistry {
         self.retain_active_event_type_registration_ids();
     }
 
-    pub(crate) fn has_listener(&self, target: EventTargetHandle, event_type: &str) -> bool {
+    pub(crate) fn has_listener(
+        &self,
+        target: EventTargetHandle,
+        event_type: &(impl EventTypeKey + ?Sized),
+    ) -> bool {
         self.handler_properties
             .get(&target)
             .and_then(|handlers| handlers.get(event_type))
@@ -1236,20 +1244,20 @@ impl HostEventTargetRegistry {
     fn ensure_event_type_registration_id(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         registration_id: u64,
     ) {
         self.event_type_registration_ids
             .entry(target)
             .or_default()
-            .entry(event_type.to_owned())
+            .entry(event_type.to_event_type())
             .or_insert(registration_id);
     }
 
     fn event_type_registration_id(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<u64> {
         self.event_type_registration_ids
             .get(&target)
@@ -1260,7 +1268,7 @@ impl HostEventTargetRegistry {
     fn event_type_has_live_registration(
         &self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> bool {
         self.listeners
             .get(&target)
@@ -1276,7 +1284,7 @@ impl HostEventTargetRegistry {
     fn remove_event_type_registration_id_if_unused(
         &mut self,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) {
         if self.event_type_has_live_registration(target, event_type) {
             return;
@@ -1284,7 +1292,7 @@ impl HostEventTargetRegistry {
         let Some(event_types) = self.event_type_registration_ids.get_mut(&target) else {
             return;
         };
-        event_types.remove(event_type);
+        event_types.shift_remove(event_type);
         if event_types.is_empty() {
             self.event_type_registration_ids.remove(&target);
         }
@@ -1315,7 +1323,7 @@ impl HostEventTargetRegistry {
         host_ptr: *mut JsContextHost,
         target: EventTargetHandle,
         invocation_target_in_shadow_tree: bool,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         event: v8::Local<'s, v8::Object>,
         capture_only: bool,
         at_target: bool,
@@ -1381,7 +1389,7 @@ impl HostEventTargetRegistry {
             tracing::info!(
                 target: "moli_cdp_nav_timing",
                 stage = "event_listener_batch_start",
-                event_type,
+                event_type = %event_type,
                 ?target,
                 capture_only,
                 at_target,
@@ -1443,7 +1451,7 @@ impl HostEventTargetRegistry {
                         tracing::debug!(
                             listener_id = listener.id,
                             ?target,
-                            event_type,
+                            event_type = %event_type,
                             "skipped event listener owned by a retired execution context"
                         );
                         continue;
@@ -1490,7 +1498,7 @@ impl HostEventTargetRegistry {
                             target: "moli_cdp_nav_timing",
                             stage = "event_listener_invoked",
                             listener_id = listener.id,
-                            event_type,
+                            event_type = %event_type,
                             ?target,
                             capture_only,
                             at_target,
@@ -1878,7 +1886,7 @@ pub(crate) fn dispatch_public_event_with_original_target<'s, 'i>(
         post_dispatch_related_target,
     )?;
     set_event_post_dispatch_source(scope, host_ptr, event, post_dispatch_source_target)?;
-    if event_type == "mouseover"
+    if event_type.is_type("mouseover")
         && !event_default_prevented(scope, event)
         && let EventTargetHandle::Node(handle) = dispatch_target
     {
@@ -1886,7 +1894,7 @@ pub(crate) fn dispatch_public_event_with_original_target<'s, 'i>(
             scope, host_ptr, handle,
         );
     }
-    if event_type == "keydown"
+    if event_type.is_type("keydown")
         && event_bool_property(scope, event, "isTrusted")
         && !event_default_prevented(scope, event)
     {
@@ -1918,9 +1926,10 @@ fn stops_submit_or_reset_at_ancestor_form(
     host_ptr: *mut JsContextHost,
     original_target: EventTargetHandle,
     current_target: EventTargetHandle,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
 ) -> bool {
-    if !matches!(event_type, "submit" | "reset") || current_target == original_target {
+    if !matches!(event_type.as_str(), Some("submit" | "reset")) || current_target == original_target
+    {
         return false;
     }
     let EventTargetHandle::Node(handle) = current_target else {
@@ -1979,7 +1988,7 @@ fn run_host_event_dispatch<'s>(
     host_ptr: *mut JsContextHost,
     dispatch_target: EventTargetHandle,
     invocation_target_in_shadow_tree: bool,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
 ) -> std::result::Result<(), String> {
     let status = call_event_target_listeners_filtered(
@@ -2139,7 +2148,7 @@ fn normalize_public_event_record<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     event: v8::Local<'s, v8::Object>,
     default_target: v8::Local<'s, v8::Value>,
-) -> std::result::Result<String, String> {
+) -> std::result::Result<EventType, String> {
     let type_key = v8str(scope, "type");
     let target_key = v8str(scope, "target");
     let current_target_key = v8str(scope, "currentTarget");
@@ -2152,7 +2161,7 @@ fn normalize_public_event_record<'s>(
     }
     let event_type = event_type_value
         .to_string(scope)
-        .map(|value| value.to_rust_string_lossy(scope))
+        .map(|value| EventType::from_v8(scope, value))
         .unwrap_or_default();
 
     let target_value =
diff --git a/moli-renderer-v8/src/lib.rs b/moli-renderer-v8/src/lib.rs
index b6a38da834..ce8e8395b1 100644
--- a/moli-renderer-v8/src/lib.rs
+++ b/moli-renderer-v8/src/lib.rs
@@ -57,6 +57,7 @@ mod document_task_lane;
 mod dom_parser;
 mod dynamic_script_owner;
 mod event_listener_args;
+mod event_type;
 mod exception_reporting;
 mod frame_owner_model;
 mod host;
diff --git a/moli-renderer-v8/src/native_bridge/abort.rs b/moli-renderer-v8/src/native_bridge/abort.rs
index e2e19a8696..6e77165414 100644
--- a/moli-renderer-v8/src/native_bridge/abort.rs
+++ b/moli-renderer-v8/src/native_bridge/abort.rs
@@ -1,3 +1,4 @@
+use crate::event_type::{EventType, EventTypeKey};
 use std::collections::{HashMap, HashSet};
 
 use super::super::document_runtime::EventTargetHandle;
@@ -68,7 +69,7 @@ struct AbortSignalState {
 
 struct AbortLinkedTargetListener {
     target: EventTargetHandle,
-    event_type: String,
+    event_type: EventType,
     callback_id: super::EventCallbackId,
     capture: bool,
 }
@@ -345,7 +346,7 @@ impl AbortStore {
         scope: &mut v8::PinScope<'s, '_>,
         signal: v8::Local<'s, v8::Object>,
         target: EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: super::EventCallbackId,
         capture: bool,
     ) {
@@ -359,7 +360,7 @@ impl AbortStore {
             .linked_target_listeners
             .push(AbortLinkedTargetListener {
                 target,
-                event_type: event_type.to_owned(),
+                event_type: event_type.to_event_type(),
                 callback_id,
                 capture,
             });
diff --git a/moli-renderer-v8/src/native_bridge/context_host/child_events.rs b/moli-renderer-v8/src/native_bridge/context_host/child_events.rs
index 8eafbab984..7bd9171e32 100644
--- a/moli-renderer-v8/src/native_bridge/context_host/child_events.rs
+++ b/moli-renderer-v8/src/native_bridge/context_host/child_events.rs
@@ -1,4 +1,5 @@
 use super::JsContextHost;
+use crate::event_type::EventTypeKey;
 use crate::{
     context_bootstrap::{
         EVENT_DISPATCHING_SLOT, EVENT_STOP_IMMEDIATE_PROPAGATION_SLOT, EVENT_STOP_PROPAGATION_SLOT,
@@ -63,7 +64,7 @@ impl JsContextHost {
     fn child_window_event_requires_runtime_dispatch(
         &self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> bool {
         self.child_window_proxy_records.has_live_window(handle)
             || self
@@ -84,7 +85,7 @@ impl JsContextHost {
     pub(crate) fn child_window_event_listener_callback_ids(
         &self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         capture: bool,
     ) -> Vec<EventCallbackId> {
         self.child_window_event_listeners
@@ -118,7 +119,7 @@ impl JsContextHost {
                     .filter_map(|entry| {
                         Some(crate::host::EventListenerInspectorSnapshot {
                             registration_id: entry.registration_id.0,
-                            event_type: event_type.clone(),
+                            event_type: event_type.as_str_lossy().to_owned(),
                             callback_id: entry.callback_state.callback_id()?,
                             capture: entry.capture,
                             once: entry.once,
@@ -132,7 +133,7 @@ impl JsContextHost {
     pub(crate) fn insert_child_window_event_listener(
         &mut self,
         target: ChildWindowEventTarget,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: EventCallbackId,
         capture: bool,
         once: bool,
@@ -141,7 +142,7 @@ impl JsContextHost {
         self.child_window_event_listeners
             .entry(target.child_handle())
             .or_default()
-            .entry(event_type.to_owned())
+            .entry(event_type.to_event_type())
             .or_default()
             .push(ChildWindowEventListenerEntry {
                 registration_id,
@@ -193,7 +194,7 @@ impl JsContextHost {
     pub(crate) fn set_child_window_event_handler_content_attribute(
         &mut self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         owner: Option<DomHandle>,
     ) -> Option<EventCallbackId> {
         match owner {
@@ -209,7 +210,7 @@ impl JsContextHost {
     fn set_child_window_event_handler_state(
         &mut self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         state: EventHandlerPropertyState,
     ) -> Option<EventCallbackId> {
         let local_window_id = self
@@ -235,7 +236,7 @@ impl JsContextHost {
         self.child_window_event_listeners
             .entry(handle)
             .or_default()
-            .entry(event_type.to_owned())
+            .entry(event_type.to_event_type())
             .or_default()
             .push(ChildWindowEventListenerEntry {
                 registration_id,
@@ -332,7 +333,7 @@ impl JsContextHost {
     fn remove_child_window_event_handler_property(
         &mut self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<EventCallbackId> {
         let target_map = self.child_window_event_listeners.get_mut(&handle)?;
         let entries = target_map.get_mut(event_type)?;
@@ -449,7 +450,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         target: ChildWindowEventTarget,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         event: v8::Local<'s, v8::Object>,
         capture_only: bool,
         at_target: bool,
@@ -527,7 +528,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         event: v8::Local<'s, v8::Object>,
     ) {
         self.dispatch_child_window_event_with_target_override(
@@ -539,7 +540,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         event: v8::Local<'s, v8::Object>,
         legacy_target_override: bool,
     ) {
@@ -634,7 +635,7 @@ impl JsContextHost {
     fn child_window_event_dispatch_slots(
         &self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         registration_kind: Option<ChildWindowEventRegistrationKind>,
         capture: Option<bool>,
     ) -> Vec<ChildWindowEventDispatchSlot> {
@@ -661,7 +662,7 @@ impl JsContextHost {
     fn child_window_event_listener_snapshot(
         &self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         slot: ChildWindowEventDispatchSlot,
     ) -> Option<ChildWindowEventListenerSnapshot> {
         let entry = self
@@ -681,7 +682,7 @@ impl JsContextHost {
     fn retire_child_window_event_registration(
         &mut self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         slot: ChildWindowEventDispatchSlot,
     ) {
         if let Some(callback_id) = self.remove_child_window_event_registration_by_id(
@@ -698,7 +699,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'_, '_>,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         slot: ChildWindowEventDispatchSlot,
     ) -> Option<ReadyChildWindowEventListenerInvocation> {
         let mut snapshot = self.child_window_event_listener_snapshot(handle, event_type, slot)?;
@@ -742,14 +743,14 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         ready: ReadyChildWindowEventListenerInvocation,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         event: v8::Local<'s, v8::Object>,
     ) -> (bool, Option<v8::Global<v8::Value>>) {
         if !self.child_window_event_target_is_current(ready.target) {
             return (false, None);
         }
         if ready.registration_kind == ChildWindowEventRegistrationKind::EventHandlerProperty
-            && event_type == "beforeunload"
+            && event_type.is_type("beforeunload")
         {
             invoke_prepared_before_unload_event_handler(
                 scope,
@@ -786,7 +787,7 @@ impl JsContextHost {
     fn remove_child_window_event_registration_by_id(
         &mut self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         registration_id: ChildWindowEventRegistrationId,
     ) -> Option<EventCallbackId> {
         let target_map = self.child_window_event_listeners.get_mut(&handle)?;
@@ -807,7 +808,7 @@ impl JsContextHost {
     pub(crate) fn remove_child_window_event_listener_by_id(
         &mut self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: EventCallbackId,
         capture: bool,
     ) -> bool {
@@ -869,7 +870,7 @@ impl JsContextHost {
     pub(crate) fn child_window_event_callback_identities_for_test(
         &self,
         handle: DomHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Vec<(
         Option<crate::native_bridge::WindowExecutionContextIdentity>,
         Option<crate::native_bridge::WindowExecutionContextIdentity>,
@@ -893,11 +894,11 @@ fn child_window_event_type_from_handler_name(name: &str) -> Option<&str> {
 fn child_window_event_callback_arguments<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     registration_kind: ChildWindowEventRegistrationKind,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
 ) -> Vec<v8::Local<'s, v8::Value>> {
     if registration_kind == ChildWindowEventRegistrationKind::EventHandlerProperty
-        && event_type == "error"
+        && event_type.is_type("error")
         && let Some(arguments) = error_event_handler_arguments(scope, event)
     {
         arguments.to_vec()
@@ -908,7 +909,7 @@ fn child_window_event_callback_arguments<'s>(
 
 fn apply_child_window_event_handler_return<'s>(
     scope: &mut v8::PinScope<'s, '_>,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
     event: v8::Local<'s, v8::Object>,
     returned: Option<v8::Global<v8::Value>>,
 ) {
@@ -916,7 +917,7 @@ fn apply_child_window_event_handler_return<'s>(
         return;
     };
     let returned = v8::Local::new(scope, returned);
-    let handler_type = if event_type == "error" && event_is_error_event(scope, event) {
+    let handler_type = if event_type.is_type("error") && event_is_error_event(scope, event) {
         EventHandlerType::OnErrorEventHandler
     } else {
         EventHandlerType::EventHandler
diff --git a/moli-renderer-v8/src/native_bridge/context_host/dom_debugger.rs b/moli-renderer-v8/src/native_bridge/context_host/dom_debugger.rs
index c6bb9aafa8..f18c88a183 100644
--- a/moli-renderer-v8/src/native_bridge/context_host/dom_debugger.rs
+++ b/moli-renderer-v8/src/native_bridge/context_host/dom_debugger.rs
@@ -1,3 +1,4 @@
+use crate::event_type::EventTypeKey;
 use std::collections::{BTreeMap, BTreeSet, HashMap};
 
 use moli_page_types::{
@@ -307,7 +308,7 @@ impl JsContextHost {
 
     pub(crate) fn schedule_dom_debugger_event_listener_pause_for_target(
         &self,
-        event_name: &str,
+        event_name: &(impl EventTypeKey + ?Sized),
         target: EventTargetHandle,
     ) -> Option<RendererDomDebuggerScheduledPause> {
         if self
@@ -332,9 +333,10 @@ impl JsContextHost {
 
     pub(crate) fn schedule_dom_debugger_event_listener_pause_for_interface(
         &self,
-        event_name: &str,
+        event_name: &(impl EventTypeKey + ?Sized),
         target_name: &str,
     ) -> Option<RendererDomDebuggerScheduledPause> {
+        let event_name = event_name.as_str()?;
         self.dom_debugger_state
             .schedule_event_listener_pause(event_name, target_name)
     }
diff --git a/moli-renderer-v8/src/native_bridge/context_host/event_callbacks.rs b/moli-renderer-v8/src/native_bridge/context_host/event_callbacks.rs
index 527ce35be0..41cb17ad28 100644
--- a/moli-renderer-v8/src/native_bridge/context_host/event_callbacks.rs
+++ b/moli-renderer-v8/src/native_bridge/context_host/event_callbacks.rs
@@ -1,4 +1,5 @@
 use super::{JsContextHost, WindowExecutionContextIdentity, WindowExecutionContextOwner};
+use crate::event_type::EventTypeKey;
 use moli_webidl_callback::{PreparedWebIdlCallbackInterface, WebIdlCallbackInterface};
 use std::collections::{HashMap, HashSet};
 
@@ -142,7 +143,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         target: crate::document_runtime::EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback: v8::Local<'s, v8::Object>,
         relevant_context: v8::Local<'s, v8::Context>,
         incumbent_context: v8::Local<'s, v8::Context>,
@@ -207,7 +208,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         target: crate::document_runtime::EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback: v8::Local<'s, v8::Object>,
         capture: bool,
     ) -> bool {
@@ -255,7 +256,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         target: crate::document_runtime::EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         handler: Option<v8::Local<'s, v8::Object>>,
     ) {
         let relevant_context = handler
@@ -278,7 +279,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         target: crate::document_runtime::EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         handler: Option<v8::Local<'s, v8::Function>>,
         target_context: v8::Local<'s, v8::Context>,
     ) {
@@ -301,7 +302,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         target: crate::document_runtime::EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         handler: Option<v8::Local<'s, v8::Object>>,
         relevant_context: v8::Local<'s, v8::Context>,
         incumbent_context: v8::Local<'s, v8::Context>,
@@ -323,7 +324,7 @@ impl JsContextHost {
         &self,
         scope: &mut v8::PinScope<'s, '_>,
         target: crate::document_runtime::EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
     ) -> Option<v8::Local<'s, v8::Value>> {
         match self.event_handler_property_callback_id(target, event_type)? {
             Some(callback_id) => self.event_callback_value(scope, callback_id),
diff --git a/moli-renderer-v8/src/native_bridge/context_host/mod.rs b/moli-renderer-v8/src/native_bridge/context_host/mod.rs
index 6eaa324b5f..37abc34196 100644
--- a/moli-renderer-v8/src/native_bridge/context_host/mod.rs
+++ b/moli-renderer-v8/src/native_bridge/context_host/mod.rs
@@ -1037,8 +1037,10 @@ pub(crate) struct JsContextHost {
     completed_child_document_networks:
         Vec<crate::protocol_types::ChildFrameDocumentNetworkActivitySnapshot>,
     active_child_subresource_request_scopes: Vec<DomHandle>,
-    child_window_event_listeners:
-        HashMap<DomHandle, IndexMap<String, Vec<ChildWindowEventListenerEntry>>>,
+    child_window_event_listeners: HashMap<
+        DomHandle,
+        IndexMap<crate::event_type::EventType, Vec<ChildWindowEventListenerEntry>>,
+    >,
     next_child_window_event_registration_id: u64,
     event_callbacks: event_callbacks::EventCallbackRegistry,
     active_window_error_report_owners: HashSet<WindowExecutionContextOwner>,
diff --git a/moli-renderer-v8/src/native_bridge/context_host/popups.rs b/moli-renderer-v8/src/native_bridge/context_host/popups.rs
index b421c19599..6b3a70cbf6 100644
--- a/moli-renderer-v8/src/native_bridge/context_host/popups.rs
+++ b/moli-renderer-v8/src/native_bridge/context_host/popups.rs
@@ -4,6 +4,7 @@ use super::{
     JsContextHost, NavigationHistoryEntrySeed, child_frame_runtime::WINDOW_EVENT_HANDLER_PROPERTIES,
 };
 use crate::document_response_decoder::decode_document_response;
+use crate::event_type::EventTypeKey;
 use crate::web_api_interfaces;
 use crate::{
     content_security_policy::content_security_policy_forces_opaque_origin,
@@ -3626,7 +3627,7 @@ impl JsContextHost {
         &mut self,
         scope: &mut v8::PinScope<'s, '_>,
         target: PopupWindowEventTarget,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         event: v8::Local<'s, v8::Object>,
         capture_only: bool,
         at_target: bool,
@@ -3649,7 +3650,7 @@ impl JsContextHost {
         let previous_message_source = self.enter_window_message_source_scope(
             super::PendingWindowMessageEndpoint::LightweightPopup(popup_id),
         );
-        let error_arguments = (event_type == "error")
+        let error_arguments = (event_type.is_type("error"))
             .then(|| crate::context_bootstrap::error_event_handler_arguments(scope, event))
             .flatten();
         let ordinary_arguments = [event.into()];
diff --git a/moli-renderer-v8/src/native_bridge/context_host/signal_bridge.rs b/moli-renderer-v8/src/native_bridge/context_host/signal_bridge.rs
index 7c4a073382..117567c890 100644
--- a/moli-renderer-v8/src/native_bridge/context_host/signal_bridge.rs
+++ b/moli-renderer-v8/src/native_bridge/context_host/signal_bridge.rs
@@ -1,4 +1,5 @@
 use super::*;
+use crate::event_type::EventTypeKey;
 
 impl JsContextHost {
     pub(crate) fn is_abort_signal<'s>(
@@ -30,7 +31,7 @@ impl JsContextHost {
         scope: &mut v8::PinScope<'s, '_>,
         signal: v8::Local<'s, v8::Object>,
         target: crate::document_runtime::EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: EventCallbackId,
         capture: bool,
     ) {
@@ -73,7 +74,7 @@ impl JsContextHost {
     pub(crate) fn remove_registered_event_listener_by_id(
         &mut self,
         target: crate::document_runtime::EventTargetHandle,
-        event_type: &str,
+        event_type: &(impl EventTypeKey + ?Sized),
         callback_id: EventCallbackId,
         capture: bool,
     ) {
diff --git a/moli-renderer-v8/src/observable/event_target.rs b/moli-renderer-v8/src/observable/event_target.rs
index fc9b75f4f7..9230d22d9b 100644
--- a/moli-renderer-v8/src/observable/event_target.rs
+++ b/moli-renderer-v8/src/observable/event_target.rs
@@ -1,3 +1,4 @@
+use crate::event_type::EventType;
 use crate::{
     abort_signal_route::ResolvedAbortSignal,
     event_listener_args::{AddEventListenerArgs, AddEventListenerOptions},
@@ -20,8 +21,8 @@ struct ObservableEventListenerOptions {
 #[derive(webidl::WebIdlArgs)]
 #[webidl(prefix = "EventTarget.when")]
 struct WhenArgs {
-    #[webidl(required, name = "type")]
-    event_type: String,
+    #[webidl(required, name = "type", converter = "raw")]
+    event_type: EventType,
     #[webidl(with = options_arg)]
     options: ObservableEventListenerOptions,
 }
@@ -43,7 +44,7 @@ fn options_arg<'s>(
 /// Observable must not keep an otherwise unreachable standalone target alive.
 pub(super) struct EventSource {
     target: v8::Weak<v8::Object>,
-    event_type: String,
+    event_type: EventType,
     options: webidl::EventListenerOptions,
     // A WindowProxy can survive navigation; retain only the exact identity,
     // never a strong context or a lookup that follows the replacement Window.
@@ -52,7 +53,7 @@ pub(super) struct EventSource {
 
 pub(super) struct PreparedEventSource<'s> {
     target: v8::Local<'s, v8::Object>,
-    event_type: String,
+    event_type: EventType,
     options: webidl::EventListenerOptions,
     window_identity: Option<WindowExecutionContextIdentity>,
 }
diff --git a/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type.js b/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type.js
new file mode 100644
index 0000000000..e6e07b4289
--- /dev/null
+++ b/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type.js
@@ -0,0 +1,92 @@
+globalThis.__probeEventListenerTypes = function eventListenerTypeRows(targets, EventCtor, OtherEventCtor = EventCtor) {
+  const rows = [];
+  const check = (name, passed) => rows.push({name, passed: !!passed});
+  const pairs = [['\ud800', '\ufffd'], ['\udc00', '\ufffd'], ['\ud800', '\ud801'],
+    ['prefix\ud800\0suffix', 'prefix\ufffd\0suffix'], ['\ud800\ud800', '\ufffd\ufffd'],
+    ['\udc00\ud800', '\ufffd\ufffd'], ['load', 'LOAD'], ['é', 'e\u0301'],
+    ['type\0', 'type'], ['\ud83d\ude80', '\ufffd\ufffd']];
+  for (const [name, target] of targets) {
+    for (const [raw, other] of pairs) {
+      const prefix = name + ' ' + JSON.stringify([raw, other]);
+      const calls = [];
+      const first = event => calls.push('first:' + (event.type === raw));
+      const second = () => calls.push('second');
+      target.addEventListener(raw, first);
+      target.addEventListener(other, second);
+      const event = new EventCtor(raw);
+      target.dispatchEvent(event);
+      check(prefix + ' distinct dispatch', calls.join(',') === 'first:true');
+      calls.length = 0;
+      target.removeEventListener(other, first);
+      target.dispatchEvent(new EventCtor(raw));
+      check(prefix + ' removal preserves other key', calls.join(',') === 'first:true');
+      target.removeEventListener(raw, first);
+      target.removeEventListener(other, second);
+      calls.length = 0;
+      const both = () => calls.push('both');
+      target.addEventListener(raw, both, {once:true});
+      target.addEventListener(other, both, {once:true});
+      target.addEventListener(raw, both, {once:false});
+      target.dispatchEvent(new EventCtor(raw));
+      target.dispatchEvent(new EventCtor(raw));
+      target.dispatchEvent(new EventCtor(other));
+      target.dispatchEvent(new EventCtor(other));
+      check(prefix + ' duplicate and once identity', calls.join(',') === 'both,both');
+      target.removeEventListener(raw, both);
+      target.removeEventListener(other, both);
+      calls.length = 0;
+      const controller = new AbortController();
+      target.addEventListener(raw, both, {signal:controller.signal});
+      target.addEventListener(other, both);
+      controller.abort();
+      target.dispatchEvent(new EventCtor(raw));
+      target.dispatchEvent(new EventCtor(other));
+      check(prefix + ' abort removes exact key', calls.join(',') === 'both');
+      target.removeEventListener(raw, both);
+      target.removeEventListener(other, both);
+      calls.length = 0;
+      let conversions = 0;
+      target.addEventListener({[Symbol.toPrimitive](hint) {
+        conversions++; check(prefix + ' string hint', hint === 'string'); return raw;
+      }}, both);
+      target.dispatchEvent(new OtherEventCtor(raw));
+      check(prefix + ' one conversion and cross realm event', conversions === 1 && calls.join(',') === 'both');
+      target.removeEventListener({toString() { conversions++; return raw; }}, both);
+      target.dispatchEvent(new EventCtor(raw));
+      check(prefix + ' converted removal', conversions === 2 && calls.join(',') === 'both');
+    }
+  }
+  return rows;
+};
+(() => {
+  const child = document.querySelector('#child').contentWindow;
+  const channel = new MessageChannel();
+  const popup = open('about:blank');
+  if (!popup) throw new Error('listener identity popup did not open');
+  const detached = document.implementation.createHTMLDocument('listener types');
+  const element = document.createElement('button');
+  document.body.appendChild(element);
+  const targets = [
+    ['EventTarget', new EventTarget()], ['Window', window], ['Document', document],
+    ['connected Element', element], ['windowless Document', detached],
+    ['detached select', detached.createElement('select')], ['child Window', child],
+    ['popup Window', popup],
+    ['MessagePort', channel.port1], ['AbortSignal', new AbortController().signal],
+    ['FileReader', new FileReader()], ['XMLHttpRequest', new XMLHttpRequest()],
+    ['XMLHttpRequestUpload', new XMLHttpRequest().upload],
+    ['MediaQueryList', matchMedia('all')], ['Performance', performance],
+    ['FontFaceSet', document.fonts]
+  ];
+  let rows;
+  try {
+    rows = __probeEventListenerTypes(targets, Event, child.Event);
+  } finally {
+    channel.port1.close();
+    channel.port2.close();
+    popup.close();
+    element.remove();
+  }
+  globalThis.__eventListenerTypeResults = {rows, passed: rows.filter(row => row.passed).length,
+    total: rows.length, targets: targets.map(([name]) => name)};
+  return rows.every(row => row.passed) || JSON.stringify(rows.filter(row => !row.passed));
+})()
diff --git a/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type.rs b/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type.rs
new file mode 100644
index 0000000000..d56f8232c4
--- /dev/null
+++ b/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type.rs
@@ -0,0 +1,45 @@
+use super::service_worker_drain::drain_service_worker_test_turn;
+use super::*;
+
+#[test]
+fn event_listener_types_preserve_utf16_identity_for_native_and_wrapper_local_targets() {
+    let mut vm = new_storage_html_test_vm("https://event-listener-type.test/");
+    vm.eval("document.body.innerHTML = '<iframe id=child></iframe>';")
+        .unwrap();
+    assert_eq!(
+        vm.eval(include_str!("event_listener_type.js")).unwrap(),
+        "true"
+    );
+}
+
+#[tokio::test]
+async fn event_listener_types_preserve_utf16_identity_in_workers_indexed_db_and_observable() {
+    let loader = ResourceRequestClient::new(&moli_fetch::FetchConfig::default()).unwrap();
+    let (mut vm, browser_context_runtime) =
+        new_service_worker_page_test_vm_with_loader_and_browser_context_runtime(
+            "https://event-listener-type-runtime.test/",
+            &loader,
+        );
+    vm.eval("document.body.innerHTML = '<iframe id=child></iframe>';")
+        .unwrap();
+    assert_eq!(
+        vm.eval(include_str!("event_listener_type.js")).unwrap(),
+        "true"
+    );
+    vm.eval(&format!(
+        "({}).then(result => globalThis.__listenerTypeDone = result, error => globalThis.__listenerTypeDone = String(error));",
+        include_str!("event_listener_type_runtime.js")
+    )).unwrap();
+    tokio::time::timeout(std::time::Duration::from_secs(10), async {
+        while vm
+            .eval("globalThis.__listenerTypeDone !== undefined")
+            .unwrap()
+            != "true"
+        {
+            drain_service_worker_test_turn(&mut vm, &browser_context_runtime, &loader).await;
+        }
+    })
+    .await
+    .expect("worker and IndexedDB listener type fixture should settle");
+    assert_eq!(vm.eval("globalThis.__listenerTypeDone").unwrap(), "true");
+}
diff --git a/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type_runtime.js b/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type_runtime.js
new file mode 100644
index 0000000000..6b1a3f7442
--- /dev/null
+++ b/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_type_runtime.js
@@ -0,0 +1,61 @@
+(async () => {
+  const rows = [];
+  const source = `const probe = ${__probeEventListenerTypes.toString()};
+    const channel = new MessageChannel();
+    try {
+      postMessage(probe([['WorkerGlobalScope', self], ['worker EventTarget', new EventTarget()],
+        ['worker AbortSignal', new AbortController().signal], ['worker MessagePort', channel.port1]], Event));
+    } finally { channel.port1.close(); channel.port2.close(); }`;
+  const url = URL.createObjectURL(new Blob([source], {type:'text/javascript'}));
+  const worker = new Worker(url);
+  try {
+    rows.push(...await new Promise((resolve, reject) => {
+      const timer = setTimeout(() => reject(new Error('worker listener identity timeout')), 5000);
+      worker.onmessage = event => { clearTimeout(timer); resolve(event.data); };
+      worker.onerror = event => { clearTimeout(timer); event.preventDefault(); reject(new Error(event.message)); };
+    }));
+  } finally { worker.terminate(); URL.revokeObjectURL(url); }
+  const name = 'event-listener-type-' + crypto.randomUUID();
+  let database;
+  try {
+    await new Promise((resolve, reject) => {
+      const request = indexedDB.open(name, 1);
+      request.onupgradeneeded = () => {
+        database = request.result;
+        const transaction = request.transaction;
+        const store = database.createObjectStore('store');
+        rows.push(...__probeEventListenerTypes([
+          ['IDBDatabase', database], ['IDBOpenDBRequest', request],
+          ['IDBTransaction', transaction], ['IDBRequest', store.get('key')]], Event));
+      };
+      request.onsuccess = () => { database = request.result; resolve(); };
+      request.onerror = () => reject(request.error);
+    });
+  } finally {
+    database?.close();
+    await new Promise((resolve, reject) => {
+      const request = indexedDB.deleteDatabase(name);
+      request.onsuccess = () => resolve();
+      request.onerror = () => reject(request.error);
+      request.onblocked = () => reject(new Error('listener identity database remained open'));
+    });
+  }
+  const channel = new MessageChannel();
+  try {
+    for (const target of [new EventTarget(), channel.port1]) {
+      const raw = '\ud800', replacement = '\ufffd', calls = [];
+      const controller = new AbortController();
+      target.when(raw).subscribe(() => calls.push('raw'), {signal:controller.signal});
+      target.when(replacement).subscribe(() => calls.push('replacement'), {signal:controller.signal});
+      target.dispatchEvent(new Event(raw));
+      rows.push({name:'Observable exact event type', passed:calls.join(',') === 'raw'});
+      controller.abort();
+      target.dispatchEvent(new Event(raw));
+      rows.push({name:'Observable abort removes exact type', passed:calls.join(',') === 'raw'});
+    }
+  } finally { channel.port1.close(); channel.port2.close(); }
+  globalThis.__eventListenerRuntimeResults = {rows, passed:rows.filter(row => row.passed).length, total:rows.length};
+  const combined = [...__eventListenerTypeResults.rows, ...rows];
+  globalThis.__eventListenerTypeResults = {rows:combined, passed:combined.filter(row => row.passed).length, total:combined.length};
+  return combined.every(row => row.passed) || JSON.stringify(combined.filter(row => !row.passed));
+})()
diff --git a/moli-renderer-v8/src/script_vm/tests/browser_api/mod.rs b/moli-renderer-v8/src/script_vm/tests/browser_api/mod.rs
index 5df16bf6e5..1055774947 100644
--- a/moli-renderer-v8/src/script_vm/tests/browser_api/mod.rs
+++ b/moli-renderer-v8/src/script_vm/tests/browser_api/mod.rs
@@ -28,6 +28,7 @@ mod document_open_origin;
 mod event_constructor_type;
 mod event_handlers;
 mod event_listener_options;
+mod event_listener_type;
 mod events_selection_storage;
 mod fontface_descriptors;
 mod fullscreen;
diff --git a/moli-renderer-v8/src/util.rs b/moli-renderer-v8/src/util.rs
index 7e6b91c7bc..895c5a49c3 100644
--- a/moli-renderer-v8/src/util.rs
+++ b/moli-renderer-v8/src/util.rs
@@ -10,7 +10,7 @@ pub use moli_v8_util::{
     initialize_ecmascript_intrinsic_registry, new_null_prototype_object, object_bool_property,
     object_chain_contains, object_defined_string_property, object_non_empty_string_property,
     object_number_property, object_own_static_bool_property,
-    object_own_static_string_property, object_property_as_array, object_property_as_object,
+    object_own_static_string_property, object_property_as_object,
     object_string_property, private_key, register_ecmascript_intrinsic,
     registered_ecmascript_constructor, registered_ecmascript_prototype, set_null_prototype,
     set_private_value, throw_range_error, throw_type_error, v8_json_parse, v8_string, v8str,
diff --git a/moli-renderer-v8/src/window_host.rs b/moli-renderer-v8/src/window_host.rs
index 8bc4016570..65ccff5840 100644
--- a/moli-renderer-v8/src/window_host.rs
+++ b/moli-renderer-v8/src/window_host.rs
@@ -50,6 +50,7 @@ use super::{
 use crate::event_listener_args::{
     AddEventListenerArgs, RemoveEventListenerArgs, parse_listener_args,
 };
+use crate::event_type::{EventType, EventTypeKey};
 use crate::web_api_interfaces;
 use moli_webapi_declare::{WebApiFunctionTemplate, WebApiObject};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
@@ -280,7 +281,7 @@ fn register_dom_event_target_listener<'s>(
     ) else {
         return;
     };
-    if call.event_type == "selectionchange"
+    if call.event_type.is_type("selectionchange")
         && target == EventTargetHandle::Node(host.document_handle())
     {
         define_non_enumerable_static_bool_property(
@@ -300,7 +301,9 @@ fn register_dom_event_target_listener<'s>(
             capture,
         );
     }
-    if !matches!(target, EventTargetHandle::ChildWindow(_)) && call.event_type == "animationstart" {
+    if !matches!(target, EventTargetHandle::ChildWindow(_))
+        && call.event_type.is_type("animationstart")
+    {
         queue_animation_start_for_listener_target(scope, host_ptr, target);
     }
 }
@@ -308,11 +311,11 @@ fn register_dom_event_target_listener<'s>(
 fn default_passive_value(
     host: &JsContextHost,
     target: EventTargetHandle,
-    event_type: &str,
+    event_type: &(impl EventTypeKey + ?Sized),
 ) -> bool {
     if !matches!(
-        event_type,
-        "touchstart" | "touchmove" | "wheel" | "mousewheel"
+        event_type.as_str(),
+        Some("touchstart" | "touchmove" | "wheel" | "mousewheel")
     ) {
         return false;
     }
@@ -459,7 +462,9 @@ pub(super) fn event_target_dispatch_event_callback<'s>(
     }
 
     set_event_trusted(scope, event, false);
-    let event_type = event_type_string(scope, event);
+    let Some(event_type) = event_type_value(scope, event) else {
+        return;
+    };
     if let Some(receiver) = window_receiver {
         let Some(binding) = receiver.resolve_live_binding(host) else {
             rv.set_bool(true);
@@ -470,12 +475,7 @@ pub(super) fn event_target_dispatch_event_callback<'s>(
             let event = v8::Local::new(scope, &event);
             let host = unsafe { &mut *host_ptr };
             if let OwnerDispatchScope::Child(handle) = dispatch_scope {
-                host.dispatch_child_window_event(
-                    scope,
-                    handle,
-                    event_type.as_deref().unwrap_or_default(),
-                    event,
-                );
+                host.dispatch_child_window_event(scope, handle, &event_type, event);
                 Ok(!crate::context_bootstrap::event_bool_attribute(
                     scope,
                     event,
@@ -484,7 +484,7 @@ pub(super) fn event_target_dispatch_event_callback<'s>(
             } else {
                 host.dispatch_public_event(scope, host_ptr, EventTargetHandle::Window, event)
                     .map(|dispatch| {
-                        if let Some(event_type) = event_type.as_deref() {
+                        if let Some(event_type) = event_type.as_str() {
                             increment_performance_event_count(scope, event_type);
                         }
                         dispatch.dispatch_event_return_value()
@@ -502,7 +502,7 @@ pub(super) fn event_target_dispatch_event_callback<'s>(
         rv.set_bool(false);
         return;
     };
-    let click_activation_target = if event_type.as_deref() == Some("click")
+    let click_activation_target = if event_type.is_type("click")
         && event_is_mouse_event(scope, event)
         && let EventTargetHandle::Node(handle) = target
     {
@@ -520,7 +520,7 @@ pub(super) fn event_target_dispatch_event_callback<'s>(
     match host.dispatch_public_event(scope, host_ptr, target, event) {
         Ok(dispatch) => {
             let return_value = dispatch.dispatch_event_return_value();
-            if let Some(event_type) = event_type.as_deref() {
+            if let Some(event_type) = event_type.as_str() {
                 increment_performance_event_count(scope, event_type);
             }
             if let Some(activation) = legacy_click_activation {
@@ -540,14 +540,14 @@ pub(super) fn event_target_dispatch_event_callback<'s>(
     }
 }
 
-fn event_type_string(
+fn event_type_value(
     scope: &mut v8::PinScope<'_, '_>,
     event: v8::Local<'_, v8::Object>,
-) -> Option<String> {
+) -> Option<EventType> {
     crate::context_bootstrap::event_backing(scope, event)
         .get(scope, v8str(scope, "type").into())
         .and_then(|value| value.to_string(scope))
-        .map(|value| value.to_rust_string_lossy(scope))
+        .map(|value| EventType::from_v8(scope, value))
 }
 
 pub(super) fn window_set_timeout_callback<'s>(