Getting active tab index of a tab using Javascript

Javascript File

function SaveActiveTabIndex(sender)
{
 var activetabindex = sender.get_activeTab().get_tabIndex();  
 setCookie(activetabindex);
}

function setCookie(value)
{
 document.cookie = "tabIndex=" + escape(value);
}

C# File
Register the tab control with OnClientActiveTabChanged.e.g.
    tabProgramInfo.OnClientActiveTabChanged = "SaveActiveTabIndex";
    and retrive the active tab index of this tab control from cookie.

   int activeTabIndex=Convert.ToInt32(Server.HtmlEncode(Request.Cookies["tabIndex"].Value));