Fixes #7229 and #5803

src/ajax.js

@@ -208,6 +208,12 @@ jQuery.extend({
 			s.data = jQuery.param( s.data, s.traditional );
 		}
 
+		// If the jsonpCallback has been set, we can assume that dataType is jsonp
+		// Ticket #5803
+		if ( s.jsonpCallback ) {
+		  s.dataType = "jsonp";
+		}
+
 		// Handle JSONP Parameter Callbacks
 		if ( s.dataType === "jsonp" ) {
 			if ( type === "GET" ) {

src/event.js

@@ -32,6 +32,9 @@ jQuery.event = {
 
 		if ( handler === false ) {
 			handler = returnFalse;
+		} else if ( !handler ) {
+		  // Fixes bug #7229. Fix recommended by jdalton
+		  return;
 		}
 
 		var handleObjIn, handleObj;