I want to display a different message if a user is currently logged in to facebook and likes the current page. I understand:
FB.Event.subscribe(\'edge.create\'
You're safer using the Graph API since Facebook is in the process of deprecating their REST API. So to get if a user likes your page, you will need the page ID and the access token of your app.
https://graph.facebook.com/me/likes/PAGE_ID?format=json&access_token=ACCESS_TOKEN