docs: private void calcPage() {
          if (navigatepageNums != null && navigatepageNums.length > 0) {
              navigateFirstPage = navigatepageNums[0];
              navigateLastPage = navigatepageNums[navigatepageNums.length - 1];
              if (pageNum > 1) {
                  prePage = pageNum - 1;
              }
              if (pageNum < pages) {
                  nextPage = pageNum + 1;
              }
          }
      }