Just adding to what Frank said. It would be great if we can export and mass update Js and Css files present in design studio. I encountered this while we are trying to figure out how to update individual asset replacing references for http with https for enabling SSL.
Let me know if there is an easier way to do it using UI.
If you just need the names of your assets, it might be worth opening the parent folder, and then copying all the content with ctrl +A - Ctrls+C, and paste it in an excel. This may be rudimentary but does help in spending less time to get the list of assets. Or if you have a web developer, they can write the code for you to fetch this information via the API.
Thanks for your reply Rachit.
We dont have a developer at our end. I think Marketo sky UI might offer this functionality. Will have to check to see whether it doesn.