jQuery validate creditcard2, how to only validate the credit card if the card is required?

问题

In my validation rules, I have the following code:

CardNumber:{
        required:function(element){ return validateIfDeposit();},
        creditcard2: function(){ return $('#CardType').val(); }
    },

The required function works great (I use it successfully for the nameOnCard field). Unfortunately the CardNumber field is still coming back invalid. How can I have the credit card field be valid if the field is not required?

来源：https://stackoverflow.com/questions/9068588/jquery-validate-creditcard2-how-to-only-validate-the-credit-card-if-the-card-is