Could you help me use rex to extract end value extensions from field values?

I have field values with the below formats and I need to extract the end value extensions like (cjs, js ..,etc) from them and store them in separate fields. Can anyone help me with this? Thanks sample=/abc/test/ipts/jquery-1.3.1-vsdoc.cjs sample=/abc/test/ipts/jquery-1.3.js