完整的JavaScript版的信用卡校验代码

 1 function isValidCreditCard(type, ccnum) {
 2    if (type == "Visa") {
 3       // Visa: length 16, prefix 4, dashes optional.
 4       var re = /^4d{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 }