Pardon me if this has more to do with HTTP than JavaScript but it's JavaScript where I'm having the problem.

My server sends something like:
Set-Cookie: foo=bar
and in my JavaScript code I try to access document.cookie but it doesn't exist. I can set cookies in my JavaScript and get them back but the Set-Cookie doesn't seem to have any effect. I've Googled every thing I can think of an all the pages I've found talk about Set-Cookie and PHP or Perl or something. I'm not sure I should expect to see the cookie but I think so. Am I missing something? (If it matters, I'm using Firefox, I have no warnings or errors during page loading, and the DOM Inspector shows no cookies.) Any insight appreciated...