ExtendScript/ActionManager code to read current Save For Web options

hey all

I am trying unsuccessfully to get the current Save For Web Options (as entered in Photoshop’s UI).

Doing a bunch of tests with ActionDescriptors, (also with the help of Humanizer or descriptor-info), but with no success.
For starters, I would like to get by script the current output format that is set in “Save for Web (Legacy
)” : GIF, JPEG, PNG-8, PNG-24, or WBMP.

Any ideas how i can fetch that with ExtendScript/ActionManager?

thnx in advance!