title: Uncaught InvalidStateError in JSON.stringify
body: <p>I've read this other thread and it was no good: <a href="https://stackoverflow.com/questions/18369280/put-data-into-json-with-jquery">Put data into JSON with Jquery</a></p>
  
  <p>Whenever I try to JSON.stringify an object array I get an error saying: </p>
  
  <pre><code>Uncaught InvalidStateError: An attempt was made to use an object that is not, or is no longer, usable. 
  </code></pre>
  
  <p>Here is my JS:</p>
  
  <pre><code>            var responseItems = [];
  
              var keynoteContainer = $('div.keynote-questions');
              var eventQuestionContainer = $('div.event-questions');
              var sessionContainer = $('div.session-questions');
              var eventId = $('#Evaluation-Event-Id').val();
  
              keynoteContainer.children().each(function (index, el) {
                  var element = $(el);
  
                  var id = "-1";
                  var parentId = element.find('input[type=hidden]').val();
                  var parentType = "Keynote";
                  var responseValue = element.find('.response-item-slider').slider("option", "value");
                  var responseText = "";
  
                  var response = { "Id": id, "EventId": eventId, "ParentId": parentId, "ParentType": parentType, "ResponseValue": responseValue, "ResponseText": responseText };
                  responseItems.push(response);
              });                    
  
              eventQuestionContainer.children().each(function (index, el) {
                  var element = $(el);
  
                  var id = "-1";
                  var parentId = element.find('input[type=hidden]').val();
                  var parentType = "EventQuestion";
                  var responseValue = element.find('.response-item-slider').slider("option", "value");
                  var responseText = element.find('textarea').val();
  
                  var response = { "Id": id, "EventId": eventId, "ParentId": parentId, "ParentType": parentType, "ResponseValue": responseValue, "ResponseText": responseText };
                  responseItems.push(response);
              });
  
              sessionContainer.children().each(function (index, el) {
                  var element = $(el);
  
                  var id = "-1";
                  var parentId = element.find('input[type=hidden]').val();
                  var parentType = "Session";
                  var responseValue = element.find('.response-item-slider').slider("option", "value");
                  var responseText = "";
  
                  var response = { "Id": id, "EventId": eventId, "ParentId": parentId, "ParentType": parentType, "ResponseValue": responseValue, "ResponseText": responseText };
                  responseItems.push(response);
              });
  
              responseItems = JSON.stringify(responseItems);
  </code></pre>
  
  <p>I've tried to log everything and it only breaks at the last line where I stringify it.</p>
  
  <p>How can I fix this? Any piece of advise or information would be highly appreciated.</p>