Get filepath from hostscriot cep

I'm trying to get the filepath or folderpath of the extension folder. The probleem is, that when I try to call this from a hostscript.jsx file it returns a random number. My guess at the moment CEP panels are loaded, there is no code available to read it.

I've tried using $.file but it keeps returning a random number. I if call the same function from a jsx file within cep panel it works. It also works to use csinterface.getSystemPath.extension

Does any one know a method or am I missing something?