How can you see your Session ID???

Peace be upon you

Some people contact me and say that the story of the session id is not reasonable :D, and it seems not OK for them to believe it :D, anyways I have a little prove here to see it,
when you log in your anything account ( yahoo,hotmail,gmail,KokoMail,... ) write this line in the address bar

javascript: window.clipboardData.setData("Text", document.cookie);window.alert('Done');

when you got the Message "Done", open the notepad and paste what in clipboard, what you are seeing is your "SESSION-ID",
it will not work in one condition, if you turn the javascript support in the browser

by the way this trick will work on any operating system with any type of browser "tested on Firefox and internet explorer", not working with Opera

thanks for your time
yours
Ahmed Essam