Thanks Erik for your response. I'm kind of a noob here. I was able to access current user's friends. However, what I want to do is to post to wall/timeline of friends or send message to them. I found this:
http://fbdevwiki.com/wiki/FB.ui#method:_.27feed.27 and thought I could try to use FB.ui, but I could not initialize the FB SDK once I already get authorized with Firebase because the site URLs for those two to work are different. Kind of clumsy explanation, hope that make sense.
Good thing I figure out that I can set the scope for auth.login to request extended permission, and there's permission to publish. However, I don't know how to write the http POST with access token in javascript (I'm using Angularjs). So I guess that's my another question.
Thanks,