i have 2 windows: window A and window B. -window A and window B have same domain -window A and window B doesn't have any parent window. first question: -is it possible for window A to get a reference of window B? second question: -what is the most elegant way to make window A notify something to window B? (modern browser supporting HTML5 restriction is not a problem) 2 ways i am aware of doing this: -messaging by server: where window B regulary asks the server if window A has notified something -messaging by local data (HTML5): when window A wants to notify something it changes the local data, window B regulary checks the local data for any change. but the 2 ways are not so elegant. for example it would be nice to get an reference of window B and using window.postMessage() (HTML5) ultimate goal is to make something like facebook where if you open 4 facebook tabs, and chat in one tab, the chat is actualized on every facebook tab, which is neat! thanks folks!