If you ignore the whole thing about how frp is not FRP, and how javascript developers really only mean frp, then a good place to start would be learning about RxJS.
FRP is deterministic and referentially transparent, frp is not. Key concepts in FRP are behaviors, events, signals; key concepts in frp is streams, observables, subscriptions. Although I'm not expert with either, there's a lot of overlap and term overloading, and I might be explaining this all badly anyway.
AFAICT, the simplest way of explaining the difference between FRP and "popular frp" is that in FRP things are described as functions of time, whereas in popular frp they are streams of events.
The "real" FRP is great for describing non-interactive things. They can be used to describe anumations: e.g. a FRP behavior can describe the position of a ball as a function of time:
ballPosition :: t -> Position
whereas in "quasi" frp, the ballPosition is a stream of Position values:
ballPosition :: (Stream Position)
Basically, quasi FRP is what you get when you sample real FRP at certain times :)
FRP is deterministic and referentially transparent, frp is not. Key concepts in FRP are behaviors, events, signals; key concepts in frp is streams, observables, subscriptions. Although I'm not expert with either, there's a lot of overlap and term overloading, and I might be explaining this all badly anyway.