Exluding JS files doesn’t work

Hello, I try to exclude specific JS file form caching.
I add new rule on the excluding tab and as URL i tryed:

custom.js

and also

https://www.domain.com/wp-content/themes/mytheme/js/custom.js

No matter what URL I add I don’t see any new entry in the file .htaccess

What can I do to properly exlud specific JS file form caching?

Thank you,

David