javascript include?

Hi,

is there a way to include another script file into the current script (and then call a function from the other script)? e.g. to build a pure "library" file with lots of functions that can then be used by various other scripts.

Is that possible?
If tried things like include(path/to/file.jsx), but that didn't work.
Couldn't find much clue in the scripting docs...

Any idea?