how to know the credit card type

[edysegura]

export function creditCardType(cc: string) {
  let amex = new RegExp('^3[47][0-9]{13}$');
  let visa = new RegExp('^4[0-9]{12}(?:[0-9]{3})?$');
  let cup1 = new RegExp('^62[0-9]{14}[0-9]*$');
  let cup2 = new RegExp('^81[0-9]{14}[0-9]*$');
 
  let mastercard = new RegExp('^5[1-5][0-9]{14}$');
  let mastercard2 = new RegExp('^2[2-7][0-9]{14}$');
 
  let disco1 = new RegExp('^6011[0-9]{12}[0-9]*$');
  let disco2 = new RegExp('^62[24568][0-9]{13}[0-9]*$');
  let disco3 = new RegExp('^6[45][0-9]{14}[0-9]*$');
 
  let diners = new RegExp('^3[0689][0-9]{12}[0-9]*$');
  let jcb =  new RegExp('^35[0-9]{14}[0-9]*$');
 
 
  if (visa.test(cc)) {
    return 'VISA';
  }
  if (amex.test(cc)) {
    return 'AMEX';
  }
  if (mastercard.test(cc) || mastercard2.test(cc)) {
    return 'MASTERCARD';
  }
  if (disco1.test(cc) || disco2.test(cc) || disco3.test(cc)) {
    return 'DISCOVER';
  }
  if (diners.test(cc)) {
    return 'DINERS';
  }
  if (jcb.test(cc)) {
    return 'JCB';
  }
  if (cup1.test(cc) || cup2.test(cc)) {
    return 'CHINA_UNION_PAY';
  }
  return undefined;
}