// Credit Card Validation Javascript
// copyright 12th May 2003, by Stephen Chapman, Felgall Pty Ltd

// You have permission to copy and use this javascript provided that
// the content of the script is not changed in any way.

function validateCreditCard(s) {
         function cardval(s) {
         // remove non-numerics
         var v = "0123456789";
         var w = "";
         for (i=0; i < s.length; i++) {
         x = s.charAt(i);
         if (v.indexOf(x,0) != -1)
         w += x;
         }

         // validate number
         j = w.length / 2;
         if (j < 6.5 || j > 8 || j == 7) return false;
         k = Math.floor(j);
         m = Math.ceil(j) - k;
         c = 0;

         for (i=0; i<k; i++) {
         a = w.charAt(i*2+m) * 2;
         c += a > 9 ? Math.floor(a/10 + a%10) : a;
         }

         for (i=0; i<k+m; i++) c += w.charAt(i*2+1-m) * 1;
         return (c%10 == 0);
}

}