Skip javascript in New Mode

I have a repeating section. It is hidden in New mode.

However, there is an event listener for this section.  When it is hidden, the javascript cannot find the control 'rptItem' and throw exception. What is the proper way to handle it? Thanks.

NWF$(document).ready(function() {
       NWF$('#' + rptItem).change(function() {itmChanged()});