[Gravity perks] Get only letters from ZIP code field?

Hi. I’m using Gravity perks “Copy Cat” perk to copy value to another field and Custom JS Plugin for Gravity Forms, to add JS code to only copy numbers/letters. Problem is, I’m very unfamiliar with JS, I got this snippet from another gravity perks dev on this forum, however this gets numbers instead of letters, any way I can make this to get letter only? Thanks.

Snippet link: Snippi

Hi Rytis,

If you have an active Gravity Perks License, you can get in touch with us via our Support Form and we’ll be happy to assist you to make the changes to the snippet.