how to avoid purging unused javascript code while using laravel mix

I have a Laravel project, and I am using laravel mix to mix my JS files

mix.js('resources/js/foo/foo.js', 'public/foo.js')

But when I run npm run prod it removes unused javascript functions and variables. I don't want this to happen as it breaks some things for my clients. How can I avoid this? I am hoping there will be an option to not purge unused functions and variables?

via Chebli Mohamed