diff --git a/compiler/cpp/src/thrift/generate/t_js_generator.cc b/compiler/cpp/src/thrift/generate/t_js_generator.cc
index 856f75c..57ec88e 100644
--- a/compiler/cpp/src/thrift/generate/t_js_generator.cc
+++ b/compiler/cpp/src/thrift/generate/t_js_generator.cc
@@ -2218,10 +2218,10 @@
   }
 
   if (include_callback) {
-    str += "callback: Function): ";
+    str += "callback: (data: " + ts_get_type(tfunction->get_returntype()) + ")=>void): ";
 
     if (gen_jquery_) {
-      str += "JQueryXHR;";
+      str += "JQueryPromise<" + ts_get_type(tfunction->get_returntype()) +">;";
     } else {
       str += "void;";
     }