var request;

$('.addEntry').submit(function (event) {

    if(validateBookYear() && validateBookAuthor() && validateBookName()) {

        var serializedData = $(this).serialize();

        if (request) {
            request.abort();
        }

        request = $.ajax({
            url: "addBook.php",
            type: "POST",
            data: serializedData
        });

        request.done(function (response, textStatus, jqXHR) {
            console.log("sucess");
        });

        request.fail(function (jqXHR, textStatus, errorThrown) {
            console.error(
                "error: " +
                textStatus, errorThrown
            );
        });
    }

    return false;
});