How to force Facebook JS-SDK to render dynamically added widgets?

Question

The content within the app is being updated using XHR. This involves changing the URL of the comment box:

Answer 1

Call the JavaScript SDK's FB.XFBML.parse(); function after you dynamically insert the fb-comments div.

See: http://developers.facebook.com/docs/reference/javascript/FB.XFBML.parse/