regex.js

 //Regex
    var visa = /^4[0-9]{12}(?:[0-9]{3})?$/;//All Visa card numbers start with a 4. New cards have 16 digits. Old cards have 13.
    var masterCard = /^5[1-5][0-9]{14}$/;//All MasterCard numbers start with the numbers 51 through 55. All have 16 digits.
    var amex = /^3[47][0-9]{13}$/;//American Express card numbers start with 34 or 37 and have 15 digits.
    var discover = /^6(?:011|5[0-9]{2})[0-9]{12}$/;//Discover card numbers begin with 6011 or 65. All have 16 digits.
    var cvv = /^[0-9]{3,4}/;//Credit cards security code. from 3 to 4 digits
    //Example
    function validate(cardType){
        var creditcard = $("#card-number").val();
        if(creditcard.match(cardType)) {
            $("p").html("This is a valid credit card number");
            $("p").css("color","green");
        } else{
            $("p").html("Error: This credit card is invalid");
            $("p").css("color","red");
        }
    }
$("button").click(function(){
    validate(visa);
});