Event: Make event dispatch optimizable by JavaScript engines

Closes gh-2834

- Do not assign to function parameters
- Do not pass arguments object to other functions

1 files changed, 9 insertions, 5 deletions

diff --git a/src/event.js b/src/event.js
index e382de6d2..4015f8768 100644
--- a/src/event.js
+++ b/src/event.js
@@ -283,19 +283,23 @@ jQuery.event = {
 		}
 	},
 
-	dispatch: function( event ) {
+	dispatch: function( nativeEvent ) {
 
 		// Make a writable jQuery.Event from the native event object
-		event = jQuery.event.fix( event );
+		var event = jQuery.event.fix( nativeEvent );
 
-		var i, j, ret, matched, handleObj,
-			handlerQueue = [],
-			args = slice.call( arguments ),
+		var i, j, ret, matched, handleObj, handlerQueue,
+			args = new Array( arguments.length ),
 			handlers = ( dataPriv.get( this, "events" ) || {} )[ event.type ] || [],
 			special = jQuery.event.special[ event.type ] || {};
 
 		// Use the fix-ed jQuery.Event rather than the (read-only) native event
 		args[ 0 ] = event;
+
+		for ( i = 1; i < arguments.length; i++ ) {
+			args[ i ] = arguments[ i ];
+		}
+
 		event.delegateTarget = this;
 
 		// Call the preDispatch hook for the mapped type, and let it bail if desired