Include Webpack and use it for jQuery, Bootstrap and chosen.js

app/javascript/packs/application.js

@@ -0,0 +1,16 @@
+/* eslint no-console:0 */
+// This file is automatically compiled by Webpack, along with any other files
+// present in this directory. You're encouraged to place your actual application logic in
+// a relevant structure within app/javascript and only use these pack files to reference
+// that code so it'll be compiled.
+//
+// To reference this file, add <%= javascript_pack_tag 'application' %> to the appropriate
+// layout file, like app/views/layouts/application.html.slim
+
+// JS
+import 'jquery'
+import 'bootstrap/dist/js/bootstrap.bundle.min';
+import 'chosen-js/chosen.jquery';
+
+// CSS
+import 'chosen-js/chosen.css';