code: function(val, fractionDigits)
      {
        return val == null || val === "" ? 0 : formatNumber(val,
        {
          minimumFractionDigits: fractionDigits == null ? 0 : fractionDigits,
          maximumFractionDigits: fractionDigits == null ? maximumFractionDigits : fractionDigits
        })
      }
docs: model -> view: formats the value when updating the input element.