Notification bar to web page similar to the SO

How do I write a notification bar in JavaScript similar to the one that you see on Stack Overflow?

In my project they are asking for one just the same as this website I wrote the code for this for this but I am not getting the exact one .,

I want to know about the cookie logic and vertical slidiing and fadeout and any modifications in the code.

An开发者_Go百科y suggestions?

Here's a jquery plugin to do exactly what you are talking about: http://tympanus.net/codrops/2009/10/29/jbar-a-jquery-notification-plugin/