根据里程数和日历年计算金额

Question

试图弄清楚如何基于日历年计算值。

$(function () {
    "use strict";
    var tbl = $('.pcd_disburse');
    tbl.find('tr').each(function () {
        // $this = this;
        $(this).find('input[type=text]').on("change", function () {
            calcMileage();
        });
    });

    function calcMileage() {
        var rateC = 0.53; // CO mileage rate 2017
        var rateB = 0.55; // CO mileage rate 2018
        var rateA = 0.58; // CO mileage rate 2019
        var getYear = $('.ndate').val();
        var year = getYear.slice(-2);
        var tbl = $('.pcd_disburse');
        tbl.find('tr').each(function () {
            var sum = 0;
            $(this).find('.ntotal').each(function () {
                if (!isNaN(this.value) && this.value.length !== 0 && year === '17') {
                    sum += parseFloat(this.value * rateC);
                } else if (!isNaN(this.value) && this.value.length !== 0 && year === '18') {
                    sum += parseFloat(this.value * rateB);
                } else {
                    sum += parseFloat(this.value * rateA);
                }
            });
            $(this).find('.miltotal').val('$' + sum.toFixed(2).replace(/(\d)(?=(\d{3})+(?!\d))/g, "$1,"));
        });
    }
});

计算不正确。目的是计算里程数乘以基于日历年的费率。任何建议表示赞赏！