//购物车-

        function Jian(obj) {

            var n = $(obj).prev().val();

            var num = parseInt(n) - 1;

            if (num == 0) {

                layer.msg("购物数量不能小于0");

                return false;

            }

            $(obj).prev().val(num);

        }

//购物车+

        function Jia(obj) {

            var n = $(obj).next().val();

            var num = parseInt(n) + 1;

            if (num == 0) {

                return;

            }

            $(obj).next().val(num);

        }