Add some functional to UI

I’d like modify UI to add some functional.

I changed on my site app/frappe/public/js/frappe/ui/listing.js and after execute bench start all changes are in sites/assets/js/list.min.js

But in repo https://github.com/frappe/bench I can’t find any .js files.

How can I change some .js or .css file and push them?

The frappe repo is https://github.com/frappe/frappe