## Implementing Luhn algorithm in JavaScript

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I'm trying to port a Luhm algorithm implementation I have that's in C# to JavaScript. I got it ported over and I thought it was working, but I can't get legitimate cards to validate. My AMEX validates fine, but my two VISAs refuse to do so. Here's the code:

luhn = function (number) { var _deltas = [0, 1, 2, 3, 4, -4, -3, -2, -1, 0], _checksum = 0, _digits = [], i, j; while (number != 0) { _digits.push(parseInt((number % 10), 10)); number = parseInt((number / 10), 10); } for (i = (_digits.length - 1), j = _digits.length; i > -1; i--) { _digit = _digits[i]; _checksum += _digit; _checksum += ((((i - j) % 2) === 0) ? _deltas[_digit] : 0); } return ((_checksum % 10) === 0); };

Can someone point me in the right direction on what's wrong? I thought this worked fine in the C# version, but now I'm having doubts... Thanks in advance!

**JavaScript fundamental (ES6 Syntax): Implement the Luhn Algorithm ,** Write a JavaScript program to implement the Luhn Algorithm used to validate a variety of identification numbers, such as credit card numbers, I am trying to implement simple validation of credit card numbers. I read about the Luhn algorithm on Wikipedia:. Counting from the check digit, which is the rightmost, and moving left, double the value of every second digit.

For others looking, below is a solution I submitted for a test :)

function validateCard(num){ var oddSum = 0; var evenSum = 0; var numToString = num.toString().split(""); for(var i = 0; i < numToString.length; i++){ if(i % 2 === 0){ if(numToString[i] * 2 >= 10){ evenSum += ((numToString[i] * 2) - 9 ); } else { evenSum += numToString[i] * 2; } } else { oddSum += parseInt(numToString[i]); } } return (oddSum + evenSum) % 10 === 0; } console.log(validateCard(41111111111111111));

**Luhn algorithm in Javascript. Check valid credit card numbers · GitHub,** test(value)) return false;. // The Luhn Algorithm. It's so pretty. let nCheck = 0 The Luhn Algorithm in JavaScript Luhn algorithm is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers Most credit cards and many government identification numbers use the algorithm as a simple method of distinguishing valid numbers from mistyped or otherwise incorrect numbers.

This solution accepts an array as a parameter. If its valid returns true and if its invalid returns false.

function validateCred(arr) { let sumArray = []; let numHolder = null; let everySecondNumber = 1; for (let i = arr.length - 1; i >= 0; i--) { if (everySecondNumber % 2 === 0) { numHolder = arr[i] * 2; if (numHolder > 9) { numHolder -= 9; } } else { numHolder = arr[i]; } sumArray.push(numHolder); everySecondNumber++; } totalSum = sumArray.reduce((acc,val) => acc + val, 0); if (totalSum % 10 == 0) { return true; } else { return false; } }

**Luhn Algorithm in JavaScript, Python, & Clojure: Part 1,** One question that appeared multiple times across a wide variety of CS101-type courses was the famous Luhn algorithm implementation. JavaScript fundamental (ES6 Syntax) exercises, practice and solution: Write a JavaScript program to implement the Luhn Algorithm used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, National Provider Identifier numbers etc.

**Implementing Luhn algorithm in JavaScript,** <script> // takes the form field value and returns true on valid number function valid_credit_card(value) { // accept only digits, dashes or spaces if JavaScript implementation of the Luhn algorithm, with calculation and validation functions. The Luhn algorithm, a simple checksum verification algorithm, is also known as Luhn formula, modulus 10 algorithm, or mod 10 algorithm. It is most notably used to validate credit card numbersand IMEI phone identification numbers.

**keywords:Luhn algorithm,** A fast Luhn algorithm for validating credit cards Collection of check digit algorithms implemented in JavaScript Credit Card validation using luhn algorithm Luhn algorithm in Javascript. Check valid credit card numbers. Raw. validate_credit_card.js. // Takes a credit card string value and returns true on valid number. function valid_credit_card(value) {. // Accept only digits, dashes or spaces. if (/[^0-9-\s]+/.test(value)) return false;

**keywords:luhn check,** Description. A fast Luhn algorithm for validating credit cards Description. Collection of check digit algorithms implemented in JavaScript Steps involved in Luhn algorithm. Consider the example of an account number “ 79927398713 “. Step 2 – If doubling of a number results in a two digits number i.e greater than 9 (e.g., 6 × 2 = 12), then add the digits of the product (e.g., 12: 1 + 2 = 3, 15: 1 + 5 = 6), to get a single digit number. Step 3 – Now take the sum of all the digits.

##### Comments

- Hint:
`alert(parseInt("54511187504546384725", 10))`

and the answer. - This works with the examples here: en.wikipedia.org/wiki/Luhn_algorithm but may not for larger numbers.