Two days ago Facebook announced a new set of JavaScript APIs that allow third party developers to write Facebook applications using the Platform APIs inside iframes on any website, not just apps.facebook.com.

This is indeed an interesting and perhaps very powerful development in the evolution of the Facebook Platform that will enable new classes of Facebook applications and websites. Additionally, web developers will now be able to more naturally take advantage of the value provided by Facebook’s “viral channels” by integrating features that just “work better” on Facebook into their existing websites.

However, the main constraint on developers using the Facebook JavaScript APIs is that, of course, you must go through Facebook to talk to the user. All JavaScript apps still require Facebook login.

The Facebook JavaScript APIs are potentially a much more viable way for Facebook to extend its reach onto the rest of the web than Beacon is (was?). Now, websites that implement Facebook JavaScript will generate a plethora of feed items inside Facebook that could in turn drive traffic back out to the app’s website. Facebook could become the platform on which news regarding your engagement with many web apps is shared.

I would like to see any examples of web apps taking advantage of the Facebook JavaScript Client Library – if you’ve built one, please let me know.