There is a session cookie with expiration time which says \'At end of session\'. When exactly does it expire or will it be alive forever?
Just to correct mingos' answer:
If you set the expiration time to 0, the cookie won't be created at all. I've tested this on Google Chrome at least, and when set to 0 that was the result. The cookie, I guess, expires immediately after creation.
To set a cookie so it expires at the end of the browsing session, simply OMIT the expiration parameter altogether.
Example:
Instead of:
document.cookie = "cookie_name=cookie_value; 0; path=/";
Just write:
document.cookie = "cookie_name=cookie_value; path=/";