code: function(){
          var me = this,
              total = me.getPageData().pageCount,
              next = me.store.currentPage + 1;
  
          if (next <= total) {
              if (me.fireEvent('beforechange', me, next) !== false) {
                  me.store.nextPage();
              }
          }
      }
docs: Move to the next page, has the same effect as clicking the 'next' button.