If a filename looks like this: Foo.Bar.txt

It will get improperly modified by subExt(), to Foo.new

The gsub line should be /\.[^.]+/ rather than /\..+/. The extension itself should not contain any periods.

Also, there is nothing wrong with adding a newext onto a file with no extension... for example, subExt("My File", "txt") should return "My File.txt".

Didn't realize I needed to click the little code button. Lemme try again: