input event added for textfield counter

Closes #3239809

js/textfield_counter.js

@@ -61,7 +61,7 @@
 
             checkClasses($(this).parent(), remaining);
 
-            $(this).keyup(function () {
+            $(this).on('input', function () {
               if (countHTML) {
                 currentLength = $(this).val().length;
               }