Move Vue.filter definition to vue_common

app/assets/javascripts/application.js

@@ -17,4 +17,5 @@
 //= require sb-admin-v2/plugins/dataTables/dataTables.bootstrap
 //= require bower/vue/dist/vue
 //= require bower/es6-promise/promise
+//= require vue_common
 //= require_tree .

app/assets/javascripts/tutorial.js

@@ -1,11 +1,6 @@
 (function(){
   "use strict";
 
-  // NOTE: should move to common space if this filter used another place
-  Vue.filter('to_json', function (value) {
-      return JSON.stringify(value);
-  })
-
   $(function(){
     if($('#chapter1').length === 0) return;
 

app/assets/javascripts/vue_common.js

@@ -0,0 +1,4 @@
+Vue.filter('to_json', function (value) {
+    return JSON.stringify(value);
+})
+