Move initialization of event until we determine if anyone wants it.

src/event.js

@@ -289,35 +289,38 @@ jQuery.event = {
 	trigger: function( event, data, elem ) {
 		// Event object or event type
 		var type = event.type || event,
-			namespaces = [];
-
-		event = typeof event === "object" ?
-			// jQuery.Event object
-			event[ jQuery.expando ] ? event :
-			// Object literal
-			jQuery.extend( jQuery.Event(type), event ) :
-			// Just the event type (string)
-			jQuery.Event(type);
+			namespaces = [],
+			exclusive;
 
 		if ( type.indexOf("!") >= 0 ) {
-			// Exclusive events trigger only for the bare event type (no namespaces)
-			event.type = type = type.slice(0, -1);
-			event.exclusive = true;
+			// Exclusive events trigger only for the exact event (no namespaces)
+			type = type.slice(0, -1);
+			exclusive = true;
 		}
 		if ( type.indexOf(".") >= 0 ) {
 			// Namespaced trigger; create a regexp to match event type in handle()
 			namespaces = type.split(".");
-			event.type = type = namespaces.shift();
+			type = namespaces.shift();
 			namespaces.sort();
 		}
-		event.namespace = namespaces.join(".");
-		event.namespace_re = new RegExp("(^|\\.)" + namespaces.join("\\.(?:.*\\.)?") + "(\\.|$)");
 
 		if ( jQuery.event.customEvent[ type ] && !jQuery.event.global[ type ] ) {
 			// No jQuery handlers for this event type, and it can't have inline handlers
 			return;
 		}
 
+		// Caller can pass in an Event, Object, or just an event type string
+		event = typeof event === "object" ?
+			// jQuery.Event object
+			event[ jQuery.expando ] ? event :
+			// Object literal
+			jQuery.extend( jQuery.Event(type), event ) :
+			// Just the event type (string)
+			jQuery.Event(type);
+		event.namespace = namespaces.join(".");
+		event.namespace_re = new RegExp("(^|\\.)" + namespaces.join("\\.(?:.*\\.)?") + "(\\.|$)");
+		event.exclusive = exclusive;
+
 		// Handle a global trigger
 		if ( !elem ) {
 			// Don't bubble custom events when global (to avoid too much overhead)