This would be useful: dataType plugins for $.ajax() et al.

Plugins could register themselves to be placed between the ajax call and the success callback so that we could say, for instance,

$.ajax({ dataType: 'yaml', … })

and automatically be given an object. The plugin might be a simple function that accepts the response text and returns whatever is appropriate.

Perhaps a more advanced plugin could specify that it wants the response to be passed to it as XML, what response mime types it accepts, etc. For instance,

$.ajax({ dataType: 'plist', … })

might pass an XML Property List to the plugin, which would return an object deserialized from from it.