在javascript中，如何惟一地从另一个浏览器窗口识别基于cookie的sessionId

The users of my web application may have more than one browser window open and pointed to the same page. I would like the state of certain things in the page (loaded via ajax) to be retained across postbacks. I can either store in a cookie or on my server. Either way, I can't think of how I can distinguish each window.The users of my web application may have more t