## Posted By

welancers on 08/14/12

# Easy Credit Card validation using Javascript

/ Published in: JavaScript

Do Credit Card validation easily using JavaScript

1. function isValidCreditCard(type, ccnum) {
2. if (type == "Visa") {
3. // Visa: length 16, prefix 4, dashes optional.
4. var re = /^4\d{3}-?\d{4}-?\d{4}-?\d{4}\$/;
5. } else if (type == "MC") {
6. // Mastercard: length 16, prefix 51-55, dashes optional.
7. var re = /^5[1-5]\d{2}-?\d{4}-?\d{4}-?\d{4}\$/;
8. } else if (type == "Disc") {
9. // Discover: length 16, prefix 6011, dashes optional.
10. var re = /^6011-?\d{4}-?\d{4}-?\d{4}\$/;
11. } else if (type == "AmEx") {
12. // American Express: length 15, prefix 34 or 37.
13. var re = /^3[4,7]\d{13}\$/;
14. } else if (type == "Diners") {
15. // Diners: length 14, prefix 30, 36, or 38.
16. var re = /^3[0,6,8]\d{12}\$/;
17. }
18. if (!re.test(ccnum)) return false;
19. // Remove all dashes for the checksum checks to eliminate negative numbers
20. ccnum = ccnum.split("-").join("");
21. // Checksum ("Mod 10")
22. // Add even digits in even length strings or odd digits in odd length strings.
23. var checksum = 0;
24. for (var i=(2-(ccnum.length % 2)); i<=ccnum.length; i+=2) {
25. checksum += parseInt(ccnum.charAt(i-1));
26. }
27. // Analyze odd digits in even length strings or even digits in odd length strings.
28. for (var i=(ccnum.length % 2) + 1; i<ccnum.length; i+=2) {
29. var digit = parseInt(ccnum.charAt(i-1)) * 2;
30. if (digit < 10) { checksum += digit; } else { checksum += (digit-9); }
31. }
32. if ((checksum % 10) == 0) return true; else return false;
33. }