how to calculte product discount from a price level in the suite commerece advance using javascript

how to calculte product discount from a price level in the suite commerece advance using javascript

// @property _DiscountPercent calculates the percentage between customers price and MSRP
    ,   _DiscountPercent: function (item)
        {
            var attributes = item.get('onlinecustomerprice') || ('pricelevel15');

            if ((pricelevel15 != 0) && (onlinecustomerprice != 0)) 

            {
                DiscountPercent = (1 - pricelevel15 / onlinecustomerprice) * 100;
            }
            else 
            {
             DiscountPercent = null;
             }
            return 'DiscountPercent';
        }

you can add this code make use f it .
thank you