In javascript, how can I uniquely identify one browser window from another which are under the same cookiedbased sessionId

you could set your own window name, the exact syntax escapes me right now, but you can use the current time and session id to create a unique id on window load, then use that id

This would be done the same way you set a name in the javascript window.open() function, (but you can do it to self, instead of new window)

googling shows:

self.window.name = myclass.getUniqueWindowId( thisSession );

UPDATE

Regarding your need to save this from refresh to refresh, i did some tests and it looks to save it from refresh to refresh. Using Firefox 3, on initial load, the window name is blank, and pressing CTRL+R over and over, and the window name was populated. i then commented out the setting the name code and reloaded and it still retained the name.

<script type="text/javascript">

    alert( self.window.name );

    self.window.name = "blah";

</script>

UPDATE

I have to make noticed the comment below on jQuery’s ‘jquery-session’ plugin, which really works and offers way more than what’s discussed here.

Although, one should also make it clear that it relies on HTML5’s Web Storage, not supported by older IE versions.

Corporate still depends heavily on IE 7 (‘and below’ here in Brazil).

Based on self.window.name, THE solution for everything non-compliant to HTML5, I offer the following code snippet as a cross-browser solution:

<script src="http://code.jquery.com/jquery-latest.min.js" type="text/javascript"></script>
<script language="javascript" type="text/jscript">
    //----------------------------------------------------------------------
    //-- guarantees that window.name is a GUID, and that it would
    //-- be preserved whilst this window's life cicle
    //----------------------------------------------------------------------
    //-- window.name will be set to "GUID-<SOME_RANDOM_GUID>"
    //----------------------------------------------------------------------

    $(window).load(
        function () {
            //----------------------
            var GUID = function () {
                //------------------
                var S4 = function () {
                    return(
                            Math.floor(
                                    Math.random() * 0x10000 /* 65536 */
                                ).toString(16)
                        );
                };
                //------------------

                return (
                        S4() + S4() + "-" +
                        S4() + "-" +
                        S4() + "-" +
                        S4() + "-" +
                        S4() + S4() + S4()
                    );
            };
            //----------------------

            if (!window.name.match(/^GUID-/)) {
                window.name = "GUID-" + GUID();
            }
        }
    ) //--------------------------------------------------------------------
</script>

I found the GUID function here (for which I proposed some code clean-up).