Separate initialize, update and destroy functions.

src/js/main.js

@@ -3,11 +3,30 @@
  */
 'use strict';
 
-var ps = require('./plugin/ps');
+var ps = require('./plugin/ps')
+  , psInstances = require('./plugin/instances');
 
 $.fn.perfectScrollbar = function (settingOrCommand) {
   return this.each(function () {
-    ps(this, settingOrCommand);
+    if (typeof settingOrCommand === 'object' ||
+        typeof settingOrCommand === 'undefined') {
+      // If it's an object or none, initialize.
+      var settings = settingOrCommand;
+
+      if (!psInstances.get(this)) {
+        ps.initialize(this, settings);
+      }
+    } else {
+      // Unless, it may be a command.
+      var command = settingOrCommand;
+
+      if (command === 'update') {
+        ps.update(this);
+      } else if (command === 'destroy') {
+        ps.destroy(this);
+      }
+    }
+
     return $(this);
   });
 };