JavaScript realizes credit card verification method _javascript Skill

This article describes the JavaScript implementation of credit card verification method. Share to everyone for your reference. The specific analysis is as follows:

Here the JavaScript version of the credit card verification code, using the Luhn algorithm

function Isvalidcreditcard (type, ccnum) {if (type = = "Visa") {//Visa:length, prefix 4, dashes optional.
  var re =/^4\d{3}-?\d{4}-?\d{4}-?\d{4}$/;
   else if (type = = "MC") {//mastercard:length, prefix 51-55, dashes optional.
  var re =/^5[1-5]\d{2}-?\d{4}-?\d{4}-?\d{4}$/;
   else if (type = = "Disc") {//discover:length, prefix 6011, dashes optional.
  var re =/^6011-?\d{4}-?\d{4}-?\d{4}$/;
   else if (type = = "AmEx") {//American express:length, prefix or 37.
  var re =/^3[4,7]\d{13}$/;
   else if (type = = "Diners") {//diners:length, prefix, or 38.
  var re =/^3[0,6,8]\d{12}$/;
  if (!re.test (Ccnum)) return false;
  Remove all dashes for the checksum//checks to eliminate negative numbers = Ccnum ("-"). Join ("");
  Checksum ("Mod")//ADD even digits in even length strings//or odd digits in odd length strings.
  var checksum = 0; For (Var i= (ccnum.length% 2); I<=ccnum.lenGth
  i+=2) {checksum + = parseint (Ccnum.charat (i-1));
  }//Analyze odd digits in even length strings//or even the digits in odd length strings.
   For (Var i= (ccnum.length% 2) + 1; i<ccnum.length; i+=2) {var digit = parseint (Ccnum.charat (i-1)) * 2;
   if (digit <) {checksum + = digit;}
  else {checksum + = (digit-9);} ' If ((checksum%) = = 0) return true;
else return false; }

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