For some time now, filenames have included the extension, so there's no need to append ".js" either on a single-file download or zip download.
While I was in the area, I also fixed .txt files in a folder - they had the same bug as scripts used to (appear in the zip as an underscore). I consolidated the code since it was the same for script files and text files.
I also added the ability to download *.js and *.ns (previously only supported *, *.script, and *.txt)
I also made the wildcard matching just a bit more flexible, so if someone really wanted to, they could go "download *blah.js" and get all scripts ending with that pattern ¯\_(ツ)_/¯