function onEvent(e,t) {
              if(e.type == 'keydown') {
                  if(e.keyCode==previousKey) { 
                      previous = t;
                      e.returnValue = false;
                  } else { if(e.keyCode==nextKey) {
                      next = t;
                      e.returnValue = false;
                  }}
              } 
          }
      "
  }
  
  }