How to to a JScript Macro?

How to do something like this?

Function fnConvTooQQ(uniBase,cantBase){

          var cantReturn;

          var factConv;

          if (uniBase=="LTA" || uniBase=="FGS" || uniBase=="QQ"){

                    cantReturn=cantBase;

          }

          else {

                    factConv = "LOAD FC as factConv FROM vConversionUM.qvd (qvd) WHERE UMO = uniBase and UMD='QQ'";

                    cantReturn = cantBase * factConv;                     

          }

          return cantReturn;

};