creditcard.js
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// http://jqueryvalidation.org/creditcard-method/
// based on http://en.wikipedia.org/wiki/Luhn_algorithm
$.validator.addMethod( "creditcard", function( value, element ) {
if ( this.optional( element ) ) {
return "dependency-mismatch";
}
// Accept only spaces, digits and dashes
if ( /[^0-9 \-]+/.test( value ) ) {
return false;
}
var nCheck = 0,
nDigit = 0,
bEven = false,
n, cDigit;
value = value.replace( /\D/g, "" );
// Basing min and max length on
// http://developer.ean.com/general_info/Valid_Credit_Card_Types
if ( value.length < 13 || value.length > 19 ) {
return false;
}
for ( n = value.length - 1; n >= 0; n-- ) {
cDigit = value.charAt( n );
nDigit = parseInt( cDigit, 10 );
if ( bEven ) {
if ( ( nDigit *= 2 ) > 9 ) {
nDigit -= 9;
}
}
nCheck += nDigit;
bEven = !bEven;
}
return ( nCheck % 10 ) === 0;
}, "Please enter a valid credit card number." );