Thanks Michael, I’ve tried Resp = JSON.parse(req.responseText) but it gave me an error:
RangeError: Invalid array length
at _NSBsubCreateArray (basicFunctions.js:1432)…
…
But your hint got me onto the right track! Since I do most of the coding in basic, I’ve started to look at the javascript the compiler produces:
Resp = JSON.parse = createMultiDimArray(req.responseText);
Without the createMultiDimArray-function, parsing works and I can finally access the values 