code: function getIframeContentJson(id, iframe) {
          /*jshint evil: true*/
  
          var response, doc, innerHtml;
  
          //IE may throw an "access is denied" error when attempting to access contentDocument on the iframe in some cases
          try {
              // iframe.contentWindow.document - for IE<7
              doc = iframe.contentDocument || iframe.contentWindow.document;
              innerHtml = doc.body.innerHTML;
  
              log("converting iframe's innerHTML to JSON");
              log("innerHTML = " + innerHtml);
              //plain text response may be wrapped in <pre> tag
              if (innerHtml && innerHtml.match(/^<pre/i)) {
                  innerHtml = doc.body.firstChild.firstChild.nodeValue;
              }
  
              response = handler._parseJsonResponse(innerHtml);
          }
          catch (error) {
              log("Error when attempting to parse form upload response (" + error.message + ")", "error");
              response = {success: false};
          }
  
          return response;
      }
docs: Returns json object received by iframe from server.