jscript function return object or JSON object

Use Case:

    Have central flow that returns a structure of 2 dates: paymentDate and payThroughDate;

     I tried two techniques that I debugged in VisualStudio and they work there. So, pasted them in to an Assign script var.

Abridged Version

subFlow:

function calcDates(frequency)

{

     logicToCalcDates;

     var pDates

     pDates = {"paymentDate":paymentDate,"payThroughDate":payThroughDate}  //JSON object

     /*

        or,

        pDates = function(){}  //jscript object

        pDates.paymentDate = paymentDate

        pDates.payThroughDate = payThroughDate

     */

}

the calling script (same flow)

Assign node

pDates = eval(calcDates("TUESDAY"))

paymentDate = pDates.paymentDate

payThroughDate = pDates.payThroughDate

At this point, both the above vars are "undefined"...... Hmmm...