what-credit-card

Validate credit card numbers using the Luhn algorithm and detect card type (Visa, MasterCard, Amex, etc.)

Features

• ✅ Validates credit card numbers using the Luhn algorithm
• 🏷️ Detects card type (Visa, MasterCard, American Express, Discover, JCB, Diners Club)
• 🛡️ Input sanitization (removes all non-digit characters)
• ❌ Comprehensive error handling
• 📝 TypeScript definitions included
• 🚀 Zero dependencies

Install

npm install what-credit-card

Usage

Basic Usage (Legacy API)

const whatCreditCard = require('what-credit-card');

console.log(whatCreditCard('4111111111111111')); // 'visa'
console.log(whatCreditCard('5555555555554444')); // 'mastercard'
console.log(whatCreditCard('1234567890123456')); // 'invalid'

Advanced Usage (New API)

const { validate, isValid, getType } = require('what-credit-card');

// Handles various formatting automatically
const result = validate('4111-1111.1111 1111');
console.log(result);
// {
//   isValid: true,
//   type: 'visa',
//   cleanNumber: '4111111111111111'
// }

// Just check if valid
console.log(isValid('4111 1111 1111 1111')); // true

// Just get card type  
console.log(getType('4111.1111.1111.1111')); // 'visa'

Error Handling

const { validate } = require('what-credit-card');

const result = validate('invalid-input');
console.log(result);
// {
//   isValid: false,
//   type: null,
//   cleanNumber: null,
//   error: 'Card number cannot be empty after removing formatting'
// }

Supported Card Types

• Visa: Cards starting with 4
• MasterCard: Cards starting with 5
• American Express: Cards starting with 34 or 37
• Discover: Cards starting with 6011 or 65
• JCB: Cards starting with 2131, 1800, or 35
• Diners Club: Cards starting with 30, 36, or 38
• Maestro: Cards starting with 50, 56-58, 6304, 6390, or 67
• UnionPay: Cards starting with 62
• Mir: Russian cards starting with 2200-2204
• Elo: Brazilian cards (various prefixes)
• Hipercard: Brazilian cards starting with 606282 or 3841
• Troy: Turkish cards starting with 9792

API

whatCreditCard(cardNumber) (Default Export)

Returns the card type as a string or 'invalid' if the card number is invalid.

Parameters:

• cardNumber (string|number): The credit card number

Returns:

• string: Card type ('visa', 'mastercard', 'amex', 'discover', 'jcb', 'dinersclub') or 'invalid'

validate(cardNumber)

Performs full validation and returns detailed information.

Parameters:

• cardNumber (string|number): The credit card number

Returns:

• object: Validation result with isValid, type, cleanNumber, and optional error

isValid(cardNumber)

Checks if the card number is valid using the Luhn algorithm.

Parameters:

• cardNumber (string|number): The credit card number

Returns:

• boolean: True if valid, false otherwise

getType(cardNumber)

Returns the card type without validation.

Parameters:

• cardNumber (string|number): The credit card number

Returns:

• string|null: Card type or null if unknown

CARD_TYPES

Array of supported card types.

Returns:

• string[]: ['amex', 'dinersclub', 'jcb', 'visa', 'mastercard', 'maestro', 'discover', 'hipercard', 'elo', 'mir', 'troy', 'unionpay']

formatCardNumber(cardNumber)

Formats a card number with appropriate spacing based on card type.

Parameters:

• cardNumber (string|number): The credit card number

Returns:

• string: Formatted card number with spaces

Example:

formatCardNumber('4532015112830366'); // Returns: '4532 0151 1283 0366'
formatCardNumber('378282246310005');  // Returns: '3782 822463 10005' (Amex format)

maskCardNumber(cardNumber, options?)

Masks a card number for secure display.

Parameters:

• cardNumber (string|number): The credit card number
• options (object, optional):
  • maskChar (string): Character to use for masking (default: '*')
  • showFirst (number): Number of first digits to show (default: 4)
  • showLast (number): Number of last digits to show (default: 4)

Returns:

• string: Masked and formatted card number

Example:

maskCardNumber('4532015112830366');                           // Returns: '4532 **** **** 0366'
maskCardNumber('4532015112830366', { maskChar: 'X' });       // Returns: '4532 XXXX XXXX 0366'
maskCardNumber('4532015112830366', { showFirst: 6, showLast: 2 }); // Returns: '4532 01** **** **66'

clearCache()

Clears the internal memoization cache for performance optimization.

Returns:

• void

Example:

clearCache(); // Clears all cached validation results

TypeScript

This package includes TypeScript definitions:

import whatCreditCard, { validate, ValidationResult } from 'what-credit-card';

const result: ValidationResult = validate('4111111111111111');
const cardType: string = whatCreditCard('4111111111111111');

License

MIT © Chirag Chauhan