cc-validate

Credit card validation powered by the Luhn algorithm, with card-type detection and number formatting. Works in Node.js with both JavaScript and TypeScript.

Live Demo

Supported Card Types

| Network | Prefix(es) | Length | |---|---|---| | Visa | 4 | 16–19 | | MasterCard | 51–55, 2221–2720 | 16 | | American Express | 34, 37 | 15 | | Discover | 6011, 622126–622925, 644–649, 65 | 16–19 | | JCB | 3528–3589 | 16–19 | | Maestro | 5018, 5020, 5038, 5893, 6304, 6759, 6761–6763 | 16–19 | | Diners Club | 300–305, 3095, 36, 38–39 | 13–19 |

Installation

npm install cc-validate

Usage

JavaScript

const { isValid } = require('cc-validate');

const result = isValid('4196 2214 3817 0266');

TypeScript

import { isValid, ValidationResult } from 'cc-validate';

const result: ValidationResult = isValid('4196 2214 3817 0266');

API

isValid(cardNumber: string): ValidationResult

Parameter: the card number as a string — spaces are ignored.

Returns a ValidationResult object:

interface ValidationResult {
    cardNumber: string;  // space-formatted number, e.g. "4196 2214 3817 0266"
    cardType:   string;  // detected network, e.g. "Visa" — "Unknown" if unrecognised
    isValid:    boolean; // true only when the Luhn check passes
    message:    string;  // human-readable result
}

Example:

isValid('4196 2214 3817 0266');
// {
//   cardNumber: '4196 2214 3817 0266',
//   cardType:   'Visa',
//   isValid:    true,
//   message:    'credit card number entered is valid'
// }

isValid('4111 2111 1111 1111');
// {
//   cardNumber: '4111 2111 1111 1111',
//   cardType:   'Visa',
//   isValid:    false,
//   message:    'credit card number entered is not valid'
// }

How It Works

The Luhn algorithm works by walking the digits from right to left, doubling every second digit (summing the two sub-digits if the result exceeds 9), then checking whether the total is divisible by 10. A detailed write-up is available in this article.

Development

# build
npm run build

# test
npm test

Changelog

| Version | Changes | |---|---| | 2.0.5 | Added live demo link | | 2.0.4 | Added Diners Club validation | | 2.0.0 | Card type detection and number formatting | | 1.0.9 | First stable release |

License

MIT — Hassan Shulli