Credit Card Type Detection

detect-card-type.js

// card type prefixes sourced from: https://en.wikipedia.org/wiki/Bank_card_number#Issuer_identification_number_.28IIN.29
var cardTypes = {
	'American Express': [
		[34],
		[37]
	],
	'Diners Club Intl': [
		[300, 305], 
		[309], 
		[36], 
		[38, 39]
	],
	'Discover': [
		[6011],
		[622126, 622925],
		[644, 649],
		[65]
	],
	'JCB': [
		[3528, 3589]
	],
	'Mastercard': [
		[50, 55]
	],
	'Visa': [
		[4]
	],
};

function startsWith (source, subString) {
	return source.indexOf(subString) === 0;
}

function between(cardNumber, x, y) {
	var cardNumberPrefix = cardNumber.substring(0, x.toString().length);
	if (isNaN(cardNumberPrefix)) return false;
	return cardNumberPrefix >= x && cardNumberPrefix <= y;
}

function detectCardType (cardNumber, prefixes) {
	for (var i = 0, n = prefixes.length; i < n; i++) {
		if (prefixes[i].length == 1) {
			if (startsWith(cardNumber, prefixes[i][0].toString())) 
				return true;
		} else if (prefixes[i].length == 2) {
			if (between(cardNumber, prefixes[i][0], prefixes[i][1])) {
				return true;
			}
		}
	}
	
	return false;
}

module.exports = function (cardNumber) {
	var cardType = '';
	
	for (var property in cardTypes) {
    	if (cardTypes.hasOwnProperty(property)) {
			if (detectCardType(cardNumber, cardTypes[property])) {
				return property;
			}
		}
	}
	
	return cardType;
};

tests.js

var detectCardType = require('./index'),
	chai = require('chai');

chai.should();

describe('detectCardType', function () {
	// AMERICAN EXPRESS
	it('should return "American Express" for a card number starting with 34', function () {
		var cardType = detectCardType('3400000000000000');
		cardType.should.equal('American Express');
	});
	
	it('should return "American Express" for a card number starting with 37', function () {
		var cardType = detectCardType('3700000000000000');
		cardType.should.equal('American Express');
	});
	
	//DINER'S CLUB INTL
	it('should return "Diners Club Intl" for a card number starting with 300', function () {
		var cardType = detectCardType('3000000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 301', function () {
		var cardType = detectCardType('3010000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 302', function () {
		var cardType = detectCardType('3020000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 303', function () {
		var cardType = detectCardType('3030000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 304', function () {
		var cardType = detectCardType('3040000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 305', function () {
		var cardType = detectCardType('3050000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 309', function () {
		var cardType = detectCardType('3090000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 36', function () {
		var cardType = detectCardType('3600000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 38', function () {
		var cardType = detectCardType('3800000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	it('should return "Diners Club Intl" for a card number starting with 39', function () {
		var cardType = detectCardType('3900000000000000');
		cardType.should.equal('Diners Club Intl');
	});
	
	// DISCOVER
	it('should return "Discover" for a card number starting with 6011', function () {
		var cardType = detectCardType('6011000000000000');
		cardType.should.equal('Discover');
	});
	
	it('should return "Discover" for a card number starting with 644', function () {
		var cardType = detectCardType('6440000000000000');
		cardType.should.equal('Discover');
	});
	
	it('should return "Discover" for a card number starting with 645', function () {
		var cardType = detectCardType('6450000000000000');
		cardType.should.equal('Discover');
	});
	
	it('should return "Discover" for a card number starting with 646', function () {
		var cardType = detectCardType('6460000000000000');
		cardType.should.equal('Discover');
	});
	
	it('should return "Discover" for a card number starting with 647', function () {
		var cardType = detectCardType('6470000000000000');
		cardType.should.equal('Discover');
	});
	
	it('should return "Discover" for a card number starting with 648', function () {
		var cardType = detectCardType('6480000000000000');
		cardType.should.equal('Discover');
	});
	
	it('should return "Discover" for a card number starting with 649', function () {
		var cardType = detectCardType('6490000000000000');
		cardType.should.equal('Discover');
	});
	
	it('should return "Discover" for a handful of card numbers between 622126 and 622925', function () {
		var cardType = detectCardType('6221260000000000');
		cardType.should.equal('Discover');
		
		cardType = detectCardType('6229250000000000');
		cardType.should.equal('Discover');
		
		cardType = detectCardType('6226250000000000');
		cardType.should.equal('Discover');
		
		cardType = detectCardType('6227250000000000');
		cardType.should.equal('Discover');
		
		cardType = detectCardType('6228250000000000');
		cardType.should.equal('Discover');
	});
	
	// JCB
	it('should return "JCB" for a handful of card numbers between 3528 and 3589', function () {
		var cardType = detectCardType('3528000000000000');
		cardType.should.equal('JCB');
		
		cardType = detectCardType('3589000000000000');
		cardType.should.equal('JCB');
		
		cardType = detectCardType('3548000000000000');
		cardType.should.equal('JCB');
		
		cardType = detectCardType('3558000000000000');
		cardType.should.equal('JCB');
		
		cardType = detectCardType('3568000000000000');
		cardType.should.equal('JCB');
	});
	
	// MASTERCARD
	it('should return "Mastercard" for a card number starting with 50', function () {
		var cardType = detectCardType('5000000000000000');
		cardType.should.equal('Mastercard');
	});
	
	it('should return "Mastercard" for a card number starting with 51', function () {
		var cardType = detectCardType('5111111111111111');
		cardType.should.equal('Mastercard');
	});
	
	it('should return "Mastercard" for a card number starting with 52', function () {
		var cardType = detectCardType('5222222222222222');
		cardType.should.equal('Mastercard');
	});
	
	it('should return "Mastercard" for a card number starting with 53', function () {
		var cardType = detectCardType('5333333333333333');
		cardType.should.equal('Mastercard');
	});
	
	it('should return Mastercard for a card number starting with 54', function () {
		var cardType = detectCardType('5444444444444444');
		cardType.should.equal('Mastercard');
	});
	
	it('should return "Mastercard" for a card number starting with 55', function () {
		var cardType = detectCardType('5555555555555555');
		cardType.should.equal('Mastercard');
	});
	
	// VISA
	it('should return "Visa" for a card number starting with 4', function () {
		var cardType = detectCardType('4111111111111111');
		cardType.should.equal('Visa');
	});
});