[Plugin: Newsletter] Custom Form Problem

Hi all!

Is it possible to add javascript code in order to turn mandatory some custom profile fields? eg: Name, Email, Profile field 1, 2, etc…

I have a profile field to enter subscribers age and I was trying to turn him mandatory by adding this code but is not working…

Here is my code: https://pastebin.com/ZK9uTuXL

Thanks in advanced for any help on this!

https://www.ads-software.com/support/plugin/newsletter