AJAX can do the job.
Go google out Javascript + XMLHttpRequest object, you can find tons of info there.

Right, you have your point here.
The stuff like what you had shown him is consider just a basic stuff. I expect he should know it.

Base on his quote, he do not want a postback. The key point I want to tell the TS is AJAX can do what he want. Otherwise, pure javascript also can, but you have to hard code the menu.