Posting a message on a friend's wall in the way as it is described in README.md is not possible any more. I'd suggest changing the example to only post on the users wall:
graph.post("/feed", wallPost, function(err, res) {
// returns the post id
console.log(res); // { id: xxxxx}
});
Removing the ability to post to friends' timelines via API
We have found that posting content via API (stream.publish) on a friend's wall lead to a high incidence of user dissatisfaction (hiding content, blocking the app). After the migration period, posting content to friends' timelines via stream.publish will no longer be allowed. Please use the Feed Dialog for posting.
Posting a message on a friend's wall in the way as it is described in README.md is not possible any more. I'd suggest changing the example to only post on the users wall:
source: https://developers.facebook.com/blog/post/2013/06/26/october-2013-platform-changes/