function luhnCheck(bankno) {

  let lastNum = bankno.substr(bankno.length - 1, 1); //取出最后一位（与luhn进行比较）

  let first15Num = bankno.substr(0, bankno.length - 1); //前15或18位

  let newArr = new Array();

  for (let i = first15Num.length - 1; i > -1; i--) { //前15或18位倒序存进数组

    newArr.push(first15Num.substr(i, 1));

  }

  let arrJiShu = new Array(); //奇数位*2的积 <9

  let arrJiShu2 = new Array(); //奇数位*2的积 >9

  let arrOuShu = new Array(); //偶数位数组

  for (let j = 0; j < newArr.length; j++) {

    if ((j + 1) % 2 == 1) { //奇数位

      if (parseInt(newArr[j]) * 2 < 9)

        arrJiShu.push(parseInt(newArr[j]) * 2);

      else

        arrJiShu2.push(parseInt(newArr[j]) * 2);

    } else //偶数位

      arrOuShu.push(newArr[j]);

  }

  let jishu_child1 = new Array(); //奇数位*2 >9 的分割之后的数组个位数

  let jishu_child2 = new Array(); //奇数位*2 >9 的分割之后的数组十位数

  for (let h = 0; h < arrJiShu2.length; h++) {

    jishu_child1.push(parseInt(arrJiShu2[h]) % 10);

    jishu_child2.push(parseInt(arrJiShu2[h]) / 10);

  }

  let sumJiShu = 0; //奇数位*2 < 9 的数组之和

  let sumOuShu = 0; //偶数位数组之和

  let sumJiShuChild1 = 0; //奇数位*2 >9 的分割之后的数组个位数之和

  let sumJiShuChild2 = 0; //奇数位*2 >9 的分割之后的数组十位数之和

  let sumTotal = 0;

  for (let m = 0; m < arrJiShu.length; m++) {

    sumJiShu = sumJiShu + parseInt(arrJiShu[m]);

  }

  for (let n = 0; n < arrOuShu.length; n++) {

    sumOuShu = sumOuShu + parseInt(arrOuShu[n]);

  }

  for (let p = 0; p < jishu_child1.length; p++) {

    sumJiShuChild1 = sumJiShuChild1 + parseInt(jishu_child1[p]);

    sumJiShuChild2 = sumJiShuChild2 + parseInt(jishu_child2[p]);

  }

  //计算总和

  sumTotal = parseInt(sumJiShu) + parseInt(sumOuShu) + parseInt(sumJiShuChild1) + parseInt(sumJiShuChild2);

  //计算luhn值

  let k = parseInt(sumTotal) % 10 == 0 ? 10 : parseInt(sumTotal) % 10;

  let luhn = 10 - k;

  if (lastNum == luhn) {

    console.log("验证通过");

    return true;

  } else {

    console.log("银行卡号必须符合luhn校验");

    return false;

  }

}

//检查银行卡号

function CheckBankNo(_bankno) {

  let bankno = _bankno.replace(/\s/g, '');

  if (bankno == "") {

    console.log("请填写银行卡号");

    return false;

  }

  if (bankno.length < 16 || bankno.length > 19) {

    console.log("银行卡号长度必须在16到19之间");

    return false;

  }

  let num = /^\d*$/; //全数字

  if (!num.exec(bankno)) {

    console.log("银行卡号必须全为数字");

    return false;

  }

  //开头6位

  let strBin = "10,18,30,35,37,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,58,60,62,65,68,69,84,87,88,94,95,98,99";

  if (strBin.indexOf(bankno.substring(0, 2)) == -1) {

    console.log("银行卡号开头6位不符合规范");

    return false;

  }

  //Luhn校验

  if (!luhnCheck(bankno)) {

    return false;

  }

  return true;

}

// 直接调用CheckBankNo方法即可

CheckBankNo(bankNo);

// 返回 true 或 false