Pardon me for not being clear, but have thia script that is really long. When I have it live, I get this error in Chrome's Console.

Uncaught TypeError: Cannot read property 'substr' of undefined

here is the snippet of code where it is reading from.

var formIddd = $('select[class~=FormField]').get(numSelec).name.substr($('select[class~=FormField]').get(numSelec).name.length-3,2);

I looked up substr on google and it appears to be a known property. I also found the classes. I have played with the lengths, but still getting stuck. It used to work until BigCommerce did an update.

Any advice much appreciated, cheers.