It really depends on what people are doing at the table and the position you are in. JJ is a very tough hand to play, sometimes I think the right move is to call and other times I think a raise, and some other times I think all-in. For instance when I have a short stack at a table im going all-in with those Jacks you most likely will get someone to call you most of the time and if not just remember that if you at least picked up something rather than losing. I mean there easily could have been an A,K,8 that came up on that flop (or something like that). So I think you play a JJ based on what position you are in.