mp.events.addDataHandler error

[Chinakomba]

Hey,
I've been coding a server and playing around with various mods on this website and I came across a function commonly used in those mods - mp.events.addDataHandler("Handle", callback);

however this always returns an error - mp.events.addDataHandler is not a function.

I could not find any documentations regarding this exact function on the wiki.

I'm programming in NodeJS.

Can anyone explain this function and why does it not work?