Script to Add File Extensions to Multiple Layers

Hi all, I'm having a hard time coming up with a quick scripting solution to help my team. We have files with 50-100 layers inside of Photoshop. We'd like to find a solution to add a .jpg file extension to the name of each layer without typing it out manually. I've found some scripts that add a generic suffix to one layer at a time, but it's not the right solution for us. For furter clarification, we don't want to overright the full name of each layer, we just want to add a file extension to each one so it exports correctly when we generate assets. Also, if anyone wants to go a step further, I would be very very interested if someone could come up with a way to add an extension to a selected group of layers in Photoshop. For example, if I selected 60 layers out of 100, ran the script, and suddenly had 60 layers renamed with a .png extension, leaving me with 40 layers with no extension at all, that would open up some really interesting workflows for us. Thanks, any responses/ideas will be super appreciated.