code: function backgroundRefreshInit(){
      if(!backgroundRefreshEnabled){
        backgroundRefreshEnabled = true;
        if(self.backgroundRefreshIntervalCheck){
          if(self.backgroundRefreshInterval > self.backgroundRefreshMinTtl){
            throw new Error('BACKGROUND_REFRESH_INTERVAL_EXCEPTION: backgroundRefreshInterval cannot be greater than backgroundRefreshMinTtl.');
          }
        }
        interval = setInterval(backgroundRefresh, self.backgroundRefreshInterval);
      }
    }
docs: Initialize background refresh