Handle Postback at Master Page using javaScript or jquery

Question

In my web application i have integrated a Chat Application developed in asp.net, Jquery and web services using sql server 2008. and i create a user control for it. i use this user control at master page.

 

 

my problem is-- i m in a chatting if there is any postback that chatbox is closed for every postback how to handle this problem please help me....

 

 

thanks in advance...