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;

test/unit/ajax.js

@@ -799,6 +799,21 @@ test("jQuery.ajax() - JSONP, Local", function() {
 			plus();
 		}
 	});
+	
+  // Supports Ticket #5803  	
+	jQuery.ajax({
+		url: "data/jsonp.php",
+		jsonpCallback: "jsonpResults",
+		success: function(data){
+			ok( data.data, "JSON results returned without dataType:jsonp when jsonpCallback is defined" );
+			plus();
+		},
+		error: function(data){
+			ok( false, "Ajax error JSON (GET, custom callback name)" );
+			plus();
+		}
+	});		
+	
 });
 
 test("JSONP - Custom JSONP Callback", function() {

test/unit/event.js

 module("event");
 
+test("null or undefined handler", function() {
+	expect(2);
+  // Supports Fixes bug #7229
+  try {
+  
+    jQuery("#firstp").click(null);
+  
+    ok(true, "Passing a null handler will not throw an exception");
+
+  } catch (e) {}  
+
+  try {
+  
+    jQuery("#firstp").click(undefined);
+  
+    ok(true, "Passing an undefined handler will not throw an exception");
+
+  } catch (e) {}  
+});
+
 test("bind(), with data", function() {
 	expect(3);
 	var handler = function(event) {