JavaScript credit card validator - checks length, prefix numbers, and checksum number

creditCardValidator.js

function creditCardValidator(cc) {
	/**
	 * Credit card validator
	 * Based on: https://www.freeformatter.com/credit-card-number-generator-validator.html
	 * and this: https://en.wikipedia.org/wiki/Payment_card_number
	 */

	// Remove all non-numeric characters
	cc = cc.toString().replace(/\D/g,'');

	// Structure of response object
	var res = {
		cc: cc,
		valid: false,
		type: null
	};

	// Validation rules
	var rules = {
		'American Express':	{
			prefix: [34, 37],
			length:	[15]
		},
		'Diners Club - Carte Blanche':	{
			prefix: [[300, 305]],
			length: [14]
		},
		'Diners Club - International':	{
			prefix: [36],
			length: [14]
		},
		'Diners Club - USA & Canada':	{
			prefix: [54],
			length: [16]
		},
		'Discover':	{
			prefix: [6011, [622126, 622925], [644, 649], 65],
			length: [16, 19]
		},
		'InstaPayment':	{
			prefix: [[637, 639]],
			length: [16]
		},
		'JCB':	{
			prefix: [[3528, 3589]],
			length: [16, 19]
		},
		'Maestro':	{
			prefix: [5018, 5020, 5038, 5893, 6304, 6759, 6761, 6762, 6763],
			length: [16, 19]
		},
		'MasterCard':	{
			prefix: [[51, 55], [222100, 272099]],
			length: [16]
		},
		'Visa':	{
			prefix: [4],
			length:	[13, 16, 19]
		},
		'Visa Electron':	{
			prefix: [4026, 417500, 4508, 4844, 4913, 4917],
			length: [16]
		}
	}

	// Validate against rules
	var validPrefix = false;
	var validLength = false;
	Object.keys(rules).forEach(function(type) {
		if(validPrefix && validLength) return;
		// Check prefixes
		var prefix = rules[type].prefix;
		validPrefix = false;
		prefix.forEach(function(p) {
			// If prefix is an array check lower and upper ends
			if(p instanceof Array) {
				if(p[0] <= cc.substr(0, p[0].toString().length) && p[1] >= cc.substr(0, p[1].toString().length)) validPrefix = true;
			}
			// If prefix is a number
			else if(typeof p == 'number') {
				if(p == cc.substr(0, p.toString().length)) validPrefix = true;
			}
		});

		if(!validPrefix) return;

		// Check length
		var length = rules[type].length;
		validLength = false;
		length.forEach(function(l) {
			// If length is an array check lower and upper ends
			if(l instanceof Array) {
				if(l[0] <= cc.length && l[1] >= cc.length) validLength = true;
			}
			// If length is a number
			else if(typeof l == 'number') {
				if(l == cc.length) validLength = true;
			}
		});

		if(validPrefix && validLength) res.type = type;
	});

	if(!(validPrefix && validLength)) return res;

	// Validate checksum using Luhn formula
	var ccCheckDigit = cc.substr(cc.length - 1); // Extract last digit
	var ccDataDigits = cc.substr(0, cc.length - 1).split('').map((d) => parseInt(d)).reverse(); // Convert digits to array, and reverse order
	ccDataDigits = ccDataDigits.map(function(d, i){
		// Odd digits: multiply by 2, then subtract 9 if > 9
		if(i % 2 === 0) {
			d = d * 2;
			return d > 9 ? d - 9 : d;
		}
		// Keep even digits as they are
		else return d;
	});
	// Add all digits
	ccDataDigits = ccDataDigits.reduce((acc, d) => acc + d);
	// Calculate check digit
	ccDataDigits = ccDataDigits % 10;
	if(ccDataDigits !== 0) ccDataDigits = 10 - ccDataDigits;
	if(ccDataDigits == ccCheckDigit) res.valid = true;

	return res;
}