What are the benefits of using FBJS vs. an iFrame with jQuery

I am looking into turning a JavaScript app (using jQuery) into a facebook widget, and am wondering what the benefit of using FBJS is over an iFrame with the app's current JavaScript code & libraries... Can any facebook app developers开发者_StackOverflow中文版 out there comment on this?

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Facebook is actually moving away from FBML/FBJS and encouraging developers to use iframes for their pages and applications:

https://developers.facebook.com/blog/post/402/

https://developers.facebook.com/blog/post/462/