pagination 分页计算

  pagination3(
    total: number, // 500 总共500条内容
    pageSize: number, // 50 一页显示50条内容
    current: number, //  1 当前第几页内容
    paginationSize: number = 10 // 可以显示多少个页码
  ) {
    var page = [];
    const pages = Math.ceil(total / pageSize);
    //const min = 1;
    const half = Math.min(
      Math.floor(pages / 2),
      Math.floor(paginationSize / 2)
    );
    let start = current - half;
    let end = current + half;

    if (start < 1) {
      end = end + -start;
      start = 1;
    }

    if (end > pages) {
      start = start - (end - pages - 1);
      end = pages;
    }

    while (start <= end) page.push(start++);

    return page;
  }