docs: function completed(event) {
              var iframeDoc;
  
              // IE < 10 (also 11?) gives 'Permission Denied' if trying to access
              // the iframeDoc from the context of the function above.
              // We need to re-get it from the DOM.
              iframeDoc = J.getIFrameDocument(iframe);
  
              // readyState === "complete" works also in oldIE.
              if (event.type === 'load' ||
                  iframeDoc.readyState === 'complete') {
  
                  // Detaching the function to avoid double execution.
                  iframe.detachEvent('onreadystatechange', completed );
                  iframeWin.detachEvent('onload', completed );
  
                  if (cb) {
                      // Some browsers fire onLoad too early.
                      // A small timeout is enough.
                      setTimeout(function() { cb(); }, 120);
                  }
              }
          }