jquery 1.x and 2.x use same api
http://lists.alioth.debian.org/pipermail/pkg-javascript-devel/2015-September/011230.html

--- a/app/assets/javascripts/application.js
+++ b/app/assets/javascripts/application.js
@@ -1,4 +1,4 @@
-/*= require jquery2 */
+/*= require jquery */
 /*= require jquery-ui/autocomplete */
 /*= require jquery-ui/datepicker */
 /*= require jquery-ui/draggable */