CODE EXAMPLE FOR JAVASCRIPT

jquery input cvv format

     function validate_cvv(cvv){

         var myRe = /^[0-9]{3,4}$/;
         var myArray = myRe.exec(cvv);
         if(cvv!=myArray)
          {
            alert("Invalid cvv number"); //invalid cvv number
            return false;
         }else{
             return true;  //valid cvv number
            }

         }