I'm not sure, but maybe it will help you...
var doc = activeDocument,
currentArtboard = getActiveArtboard();
/* ======================== */
alert(currentArtboard);
/* ======================== */
function getActiveArtboard() {
while(true) {
if (isArtboardLayer()) {
return doc.activeLayer
}
selectForwardLayer();
}
}
function isArtboardLayer() {
var ref = new ActionReference();
ref.putEnumerated(charIDToTypeID("Lyr "), charIDToTypeID("Ordn"), charIDToTypeID("Trgt"));
var isArtboardLayer = executeActionGet(ref).getBoolean(stringIDToTypeID("artboardEnabled"));
return isArtboardLayer
}
function selectForwardLayer() {
var desc = new ActionDescriptor();
var ref = new ActionReference();
ref.putEnumerated(charIDToTypeID('Lyr '), charIDToTypeID('Ordn'), charIDToTypeID('Frwr'));
desc.putReference(charIDToTypeID('null'), ref);
desc.putBoolean(charIDToTypeID('MkVs'), false);
executeAction(charIDToTypeID('slct'), desc, DialogModes.NO);
}