There are 2 Javascript functions that are injected by the SDK into any page you load:
RadiantUI.TriggerEvent(“EventName”, … (arguments)); // Will execute a function named EventName on whatever Unreal class you are using to run the webpage and pass it the parameters requested. If the argument types don’t match the UFUNCTION an error is reported and the method isn’t called.
RadiantUI.SetCallback(“NameOfCallback”, function()); // Binds a javascript function named “NameOfCallback” to the function you provide. Blueprints or C++ can call this function, see the video tutorials.
Hopefully that is useful.