Alternative to the CC Embed which doesn't error handle correctly for me

ccembed.html

<script>
  $(document).ready(function() {
    $("#ctct_signup").submit(function(e) {
      var formData = $("#ctct_signup").serialize();
      $.ajax({
        type : 'POST', 
        url : 'https://visitor2.constantcontact.com/api/signup', 
        data : formData, 
        dataType : 'json',
        success: function(data){
             $("#ctct-messages").html("<p>Thank you for joining our mailing list!</p>");
        },
        error: function(response) {
          var respText = JSON.parse(response.responseText);
          $("#ctct-messages").empty();
          $.each(respText.offenders, function(i,obj){
              $("#ctct-messages").append("<p>" + obj.err + "</p>");
          });
          //$("#ctct-messages").html("<p>" + respText.offenders[0].err + "</p>");
      });
      e.preventDefault();
    });
});
</script>

<div id="ctct-messages"></div>
<form id="ctct_signup" action="https://visitor2.constantcontact.com/api/signup" method="post">
  <p>Join our email list to receive updates and specials!</p>
  <input name="email" type="email" placeholder="Email" size="30" required>
  <br/><br/>
  <input name="first_name" placeholder="First name" size="30"><br/><br/>
  <input type="hidden" name="ca" value="your-ca-value">
  <input type="submit">
</form>

</body>