Execute javascript code within the viewer

Hello, I'm trying to find a way to execute some javascript code defined on the html page that embeds the krpano viewer, however I want to execute that function when a certain action inside the viewer is done, for example onlick, or on hotspot click, etc. I already have seen the javascript interface that allow us to execute an action within a javascript function, but the inverse is possible? An action that executes code on the web page. Thanks a lot.