diff --git a/src/js/lib/event-class.js b/src/js/lib/event-class.js
new file mode 100644
index 0000000..6ccf351
--- /dev/null
+++ b/src/js/lib/event-class.js
@@ -0,0 +1,17 @@
+/* Copyright (c) 2015 Hyunje Alex Jun and other contributors
+ * Licensed under the MIT License
+ */
+'use strict';
+
+var incrementingId = 0;
+module.exports = function () {
+  var id = incrementingId++;
+  return function (eventName) {
+    var className = '.perfect-scrollbar-' + id;
+    if (typeof eventName === 'undefined') {
+      return className;
+    } else {
+      return eventName + className;
+    }
+  };
+};
diff --git a/src/js/plugin/ps.js b/src/js/plugin/ps.js
index 77fa206..324be22 100644
--- a/src/js/plugin/ps.js
+++ b/src/js/plugin/ps.js
@@ -5,21 +5,9 @@
 
 var cls = require('../lib/class')
   , defaultSettings = require('./default-setting')
+  , eventClassFactory = require('../lib/event-class')
   , h = require('../lib/helper');
 
-var incrementingId = 0;
-var eventClassFactory = function () {
-  var id = incrementingId++;
-  return function (eventName) {
-    var className = '.perfect-scrollbar-' + id;
-    if (typeof eventName === 'undefined') {
-      return className;
-    } else {
-      return eventName + className;
-    }
-  };
-};
-
 module.exports = function (element, settingOrCommand) {
   var settings = h.clone(defaultSettings);
   var $this = $(element);