信用卡检查器 luhn 算法 javascript

Question

我目前正在制作信用卡检查器（Luhn algorithm) from the Codecademy project 但我的功能似乎不起作用，因为它返回“false”，数组必须 return “true "(valid3)。有人能帮帮我吗？

// All valid credit card numbers
const valid1 = [4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8];
const valid2 = [5, 5, 3, 5, 7, 6, 6, 7, 6, 8, 7, 5, 1, 4, 3, 9];
const valid3 = [3, 7, 1, 6, 1, 2, 0, 1, 9, 9, 8, 5, 2, 3, 6];
const valid4 = [6, 0, 1, 1, 1, 4, 4, 3, 4, 0, 6, 8, 2, 9, 0, 5];
const valid5 = [4, 5, 3, 9, 4, 0, 4, 9, 6, 7, 8, 6, 9, 6, 6, 6];

// All invalid credit card numbers
const invalid1 = [4, 5, 3, 2, 7, 7, 8, 7, 7, 1, 0, 9, 1, 7, 9, 5];
const invalid2 = [5, 7, 9, 5, 5, 9, 3, 3, 9, 2, 1, 3, 4, 6, 4, 3];
const invalid3 = [3, 7, 5, 7, 9, 6, 0, 8, 4, 4, 5, 9, 9, 1, 4];
const invalid4 = [6, 0, 1, 1, 1, 2, 7, 9, 6, 1, 7, 7, 7, 9, 3, 5];
const invalid5 = [5, 3, 8, 2, 0, 1, 9, 7, 7, 2, 8, 8, 3, 8, 5, 4];

// An array of all the arrays above
const batch = [valid1, valid2, valid3, valid4, valid5, invalid1, invalid2, invalid3, invalid4, invalid5];

// Add your functions below:

function validateCred(arr) {
  let reverseArr = arr.reverse()
  let sum = 0;
  for (let i = 0; i < reverseArr.length; i += 2) {
    sum += reverseArr[i];
    sum += reverseArr[i + 1] * 2;
    if (reverseArr[i + 1] * 2 > 9) {
      sum -= 9;
    }
  }
  if (sum % 10 === 0) {
    return true
  } else {
    return false
  }
}

function findInvalidCards(arr000) {
  let invalidArr = []
  for (let j = 0; j < arr000.length; j++) {
    if (validateCred(arr000[j]) === false) {
      invalidArr.push(arr000[j])
    }
  }
  return invalidArr;
}

let arr = [4, 5, 5, 6, 7, 3, 7, 5, 8, 6, 8, 9, 9, 8, 5]
let arr1 = 6
console.log(validateCred(valid3))

console.log(findInvalidCards(batch))

Answer 1

valid3 具有奇数个元素，因此 reverseArr[i + 1] 在 validateCred 中变为未定义。也许你可以在将它添加到总和之前检查 reverseArr[i + 1] 是否有值：

// All valid credit card numbers
const valid1 = [4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8];
const valid2 = [5, 5, 3, 5, 7, 6, 6, 7, 6, 8, 7, 5, 1, 4, 3, 9];
const valid3 = [3, 7, 1, 6, 1, 2, 0, 1, 9, 9, 8, 5, 2, 3, 6];
const valid4 = [6, 0, 1, 1, 1, 4, 4, 3, 4, 0, 6, 8, 2, 9, 0, 5];
const valid5 = [4, 5, 3, 9, 4, 0, 4, 9, 6, 7, 8, 6, 9, 6, 6, 6];

// All invalid credit card numbers
const invalid1 = [4, 5, 3, 2, 7, 7, 8, 7, 7, 1, 0, 9, 1, 7, 9, 5];
const invalid2 = [5, 7, 9, 5, 5, 9, 3, 3, 9, 2, 1, 3, 4, 6, 4, 3];
const invalid3 = [3, 7, 5, 7, 9, 6, 0, 8, 4, 4, 5, 9, 9, 1, 4];
const invalid4 = [6, 0, 1, 1, 1, 2, 7, 9, 6, 1, 7, 7, 7, 9, 3, 5];
const invalid5 = [5, 3, 8, 2, 0, 1, 9, 7, 7, 2, 8, 8, 3, 8, 5, 4];

// An array of all the arrays above
const batch = [valid1, valid2, valid3, valid4, valid5, invalid1, invalid2, invalid3, invalid4, invalid5];

// Add your functions below:

function validateCred(arr) {
  let reverseArr = [...arr].reverse()
  let sum = 0;
  for (let i = 0; i < reverseArr.length; i += 2) {
    sum += reverseArr[i];
    
    if(reverseArr[i + 1]) { // Check reverseArr[i + 1] has a value
      sum += reverseArr[i + 1] * 2;
      if (reverseArr[i + 1] * 2 > 9) {
        sum -= 9;
      }
    }
  }
  
  return sum % 10 === 0;
}


console.log(batch.map(validateCred))

信用卡检查器 luhn 算法 javascript

Credit card checker luhn algorithm javascript

javascript

arrays

algorithm

credit-card

function