LibWeb: Adjust implementation of Document::create_event

With this change, it no longer calls TODO() and crashes WebContent

Userland/Libraries/LibWeb/DOM/Document.cpp

@@ -952,10 +952,15 @@ NonnullRefPtr<Range> Document::create_range()
 }
 
 // https://dom.spec.whatwg.org/#dom-document-createevent
-NonnullRefPtr<Event> Document::create_event(String const& interface)
+DOM::ExceptionOr<NonnullRefPtr<Event>> Document::create_event(String const& interface)
 {
-    auto interface_lowercase = interface.to_lowercase();
+    // NOTE: This is named event here, since we do step 5 and 6 as soon as possible for each case.
+    // 1. Let constructor be null.
     RefPtr<Event> event;
+
+    // 2. If interface is an ASCII case-insensitive match for any of the strings in the first column in the following table,
+    //      then set constructor to the interface in the second column on the same row as the matching string:
+    auto interface_lowercase = interface.to_lowercase();
     if (interface_lowercase == "beforeunloadevent") {
         event = Event::create(""); // FIXME: Create BeforeUnloadEvent
     } else if (interface_lowercase == "compositionevent") {
@@ -992,17 +997,29 @@ NonnullRefPtr<Event> Document::create_event(String const& interface)
         event = Event::create(""); // FIXME: Create TouchEvent
     } else if (interface_lowercase.is_one_of("uievent", "uievents")) {
         event = UIEvents::UIEvent::create("");
-    } else {
-        // FIXME:
-        // 3. If constructor is null, then throw a "NotSupportedError" DOMException.
-        // 4. If the interface indicated by constructor is not exposed on the relevant global object of this, then throw a "NotSupportedError" DOMException.
-        TODO();
     }
-    // Setting type to empty string is handled by each constructor.
+
-    // FIXME:
+    // 3. If constructor is null, then throw a "NotSupportedError" DOMException.
-    // 7. Initialize event’s timeStamp attribute to a DOMHighResTimeStamp representing the high resolution time from the time origin to now.
+    if (!event) {
+        return DOM::NotSupportedError::create("No constructor for interface found");
+    }
+
+    // FIXME: 4. If the interface indicated by constructor is not exposed on the relevant global object of this, then throw a "NotSupportedError" DOMException.
+
+    // NOTE: These are done in the if-chain above
+    // 5. Let event be the result of creating an event given constructor.
+    // 6. Initialize event’s type attribute to the empty string.
+    // NOTE: This is handled by each constructor.
+
+    // FIXME: 7. Initialize event’s timeStamp attribute to the result of calling current high resolution time with this’s relevant global object.
+
+    // 8. Initialize event’s isTrusted attribute to false.
     event->set_is_trusted(false);
+
+    // 9. Unset event’s initialized flag.
     event->set_initialized(false);
+
+    // 10. Return event.
     return event.release_nonnull();
 }
 

Userland/Libraries/LibWeb/DOM/Document.h

@@ -186,7 +186,7 @@ public:
     NonnullRefPtr<Text> create_text_node(String const& data);
     NonnullRefPtr<Comment> create_comment(String const& data);
     NonnullRefPtr<Range> create_range();
-    NonnullRefPtr<Event> create_event(String const& interface);
+    ExceptionOr<NonnullRefPtr<Event>> create_event(String const& interface);
 
     void set_pending_parsing_blocking_script(Badge<HTML::HTMLScriptElement>, HTML::HTMLScriptElement*);
     HTML::HTMLScriptElement* pending_parsing_blocking_script() { return m_pending_parsing_blocking_script; }