I normally comment and uncomment code with XCode using this command:
(command+slash)
This works just fine for swift file, but it does NOT work for javascript files. Is there way I can configure XCode to do this for all files?
I don't think it's possible to extend the standard comment out command to Javascript as well, sorry :-(
Having said that, you could try adding a custom shortcut following these steps. (But might be tricky to completely reproduce the native comment out behavior.)