Thanks for raising the issue. I just pushed version 3.0-1594 that adds the missing functionality.
The REST API call, /bgp/routepusher/{router}/json, returns a list of prefixes.
In the JavaScript API, bgpRoutes(router), performs the same function. There is also a new JavaScript function, bgpGetRoute(router,prefix), to query the route options for the prefix.
FYI The ddos-protect application (
https://github.com/sflow-rt/ddos-protect) keeps track of the BGP Flowspec rules / RTBH routes that it adds and removes in a JavaScript object, along with other metadata about the traffic condition triggering the control.