by value distribute spacing

These should help you out (scripts below),

but I have an additional query, as to how you get the same results but with “Aling to Key Object” selection?

Horizontally:

app.activeDocument.distribute(app.selection, DistributeOptions.HORIZONTAL_SPACE, undefined, true, "1 p");

Vertically:

app.activeDocument.distribute(app.selection, DistributeOptions.VERTICAL_SPACE, undefined, true, "1p");

Thanks.

Align to Key Object activated on image frame on the right. Causing distribute script to fail.

Adobe InDesign CS6 (8.0) Object Model JS: Document

and less so http://jongware.mit.edu/idcs6js/pc_AlignDistributePreference.html