Javascript get credit card type helper

// http://stackoverflow.com/questions/72768/how-do-you-detect-credit-card-type-based-on-number
this.getCreditCardType = function(number) {

	if (!number) {
		return undefined;
	};

	// trim whitesapce
	number = number.replace(/\s+/g, '');

	// MasterCard
	if (/^5[1-5][0-9]{5,}$/.test(number)) {
		return 'mastercard';
	}

	// Visa
	else if (/^4[0-9]{6,}$/.test(number)) {
		return 'visa';
	}

	// AmEx
	else if (/^3[47][0-9]{5,}$/.test(number)) {
		return 'amex';
	}

	// Diners Club
	else if (/^3(?:0[0-5]|[68][0-9])[0-9]{4,}$/.test(number)) {
		return 'diners';
	}

	// Discover
	else if (/^6(?:011|5[0-9]{2})[0-9]{3,}$/.test(number)) {
		return 'discover';
	}

	// JCB
	else if (/^(?:2131|1800|35[0-9]{3})[0-9]{3,}$/.test(number)) {
		return 'jcb';
	}

	return undefined;
};