Can we query from Javascript?

The simplest example would be presenting the average rating of a game to a user.  We'd like to search for each rating of this game entry and then take the average in the same javascript that handles the interface.  A simple hack would be create a search card that finds these ratings in open view and then uses javascript to hide all the searched items, displaying only the average rating.  But obviously that's not a permanent solution (and it doesn't solve more complex use cases).  Can we do this without editing the underlying ruby code or other internals of the Wagn site?  For now we're using the default hosting through cloudstore, but we'd be willing to host it ourselves and make simple modifications if there's no other way.