How to Show or Hide the Online Status on Facebook Chat?

When you're online chat on Facebook, maybe there some friends who you don't want as a chat friend, even you don't want your online status visible to them. Or maybe you don't want to get caught with your ex-girlfriend while you online chat on Facebook? So, what should you do? Relax, Facebook was offering a way that allows you to fully control who can communicate with you through the online status