For questions about caching results of API calls and / or how caching affects user scripts when used on the Stack Exchange sites.
General caching issues with browsers should be asked on Super User. How to implement caching in your favorite toolstack is probably already answered on Stack Overflow and if not, questions about it should go there.
Keep in mind that caching can be done on the client (aka a browser), intermediate HTTP proxy servers or at the server itself. Make sure you have worked out where the caching you ask about takes place and/or for which caching scenario you expect an answer. The solutions for each type of caching differ widely.