code: function ( index, direction, router ) {
  			var current = F.current;
  
  			if (!current) {
  				return;
  			}
  
  			index = getScalar(index);
  
  			F.direction = direction || current.direction[ (index >= current.index ? 'next' : 'prev') ];
  			F.router    = router || 'jumpto';
  
  			if (current.loop) {
  				if (index < 0) {
  					index = current.group.length + (index % current.group.length);
  				}
  
  				index = index % current.group.length;
  			}
  
  			if (current.group[ index ] !== undefined) {
  				F.cancel();
  
  				F._start(index);
  			}
  		}
docs: Navigate to gallery item by index