js 銀行卡號校驗

示例：luhnCheck(62155937000139567)

function luhnCheck(bankno) {
    var lastNum = bankno.substr(bankno.length - 1, 1); //取出最后一位（與luhn進行比較）
    var first15Num = bankno.substr(0, bankno.length - 1); //前15或18位
    var newArr = new Array();
    for (var i = first15Num.length - 1; i > -1; i--) { //前15或18位倒序存進數組
        newArr.push(first15Num.substr(i, 1));
    }
    var arrJiShu = new Array(); //奇數位*2的積 <9
    var arrJiShu2 = new Array(); //奇數位*2的積 >9
    var arrOuShu = new Array(); //偶數位數組
    for (var j = 0; j < newArr.length; j++) {
        if ((j + 1) % 2 == 1) { //奇數位
            if (parseInt(newArr[j]) * 2 < 9) arrJiShu.push(parseInt(newArr[j]) * 2);
            else arrJiShu2.push(parseInt(newArr[j]) * 2);
        } else //偶數位
        arrOuShu.push(newArr[j]);
    }
    var jishu_child1 = new Array(); //奇數位*2 >9 的分割之后的數組個位數
    var jishu_child2 = new Array(); //奇數位*2 >9 的分割之后的數組十位數
    for (var h = 0; h < arrJiShu2.length; h++) {
        jishu_child1.push(parseInt(arrJiShu2[h]) % 10);
        jishu_child2.push(parseInt(arrJiShu2[h]) / 10);
    }
    var sumJiShu = 0; //奇數位*2 < 9 的數組之和
    var sumOuShu = 0; //偶數位數組之和
    var sumJiShuChild1 = 0; //奇數位*2 >9 的分割之后的數組個位數之和
    var sumJiShuChild2 = 0; //奇數位*2 >9 的分割之后的數組十位數之和
    var sumTotal = 0;
    for (var m = 0; m < arrJiShu.length; m++) {
        sumJiShu = sumJiShu + parseInt(arrJiShu[m]);
    }
    for (var n = 0; n < arrOuShu.length; n++) {
        sumOuShu = sumOuShu + parseInt(arrOuShu[n]);
    }
    for (var p = 0; p < jishu_child1.length; p++) {
        sumJiShuChild1 = sumJiShuChild1 + parseInt(jishu_child1[p]);
        sumJiShuChild2 = sumJiShuChild2 + parseInt(jishu_child2[p]);
    }
    //計算總和
    sumTotal = parseInt(sumJiShu) + parseInt(sumOuShu) + parseInt(sumJiShuChild1) + parseInt(sumJiShuChild2);
    //計算luhn值
    var k = parseInt(sumTotal) % 10 == 0 ? 10 : parseInt(sumTotal) % 10;
    var luhn = 10 - k;
    if (lastNum == luhn) {
        // $("#banknoInfo").html("luhn驗證通過");
        return true;
    } else {
        // $("#banknoInfo").html("銀行卡號必須符合luhn校驗");
        return false;
    }
}