Detect credit card type based on the number

getcctype.js

function getCCType(ccnumber) {
  var visaRE = /^4[0-9]{12}(?:[0-9]{3})?$/;
  var mastercardRE = /^5[1-5][0-9]{14}$/;
  var amexRE = /^3[47][0-9]{13}$/;
  var discoverRE = /^6(?:011|5[0-9]{2})[0-9]{12}$/;
  var dinersclubRE = /^3(?:0[0-5]|[68][0-9])[0-9]{11}$/;
  var jcbRE = /^(?:2131|1800|35\d{3})\d{11}$/;
  
  ccnumber = (ccnumber || '').replace(/[ -]/g, '');
  if (ccnumber.match(visaRE)) return 'visa';
  if (ccnumber.match(mastercardRE)) return 'mastercard';
  if (ccnumber.match(amexRE)) return 'americanexpress';
  if (ccnumber.match(discoverRE)) return 'discover';
  if (ccnumber.match(dinersclubRE)) return 'dinersclub';
  if (ccnumber.match(jcbRE)) return 'jcb';
  return 'unknown';
}