pagination.utils.ts

export interface PaginationOptions {
  total: number;
  current: number;
  noOfSiblings?: number;
}

export function pagination(options: PaginationOptions) {
  const { total, noOfSiblings, current } = validate(options);

  const max = 2 * noOfSiblings + 5;
  const breakpoint = noOfSiblings + 3;

  const needEllipsis = total > max;
  const pages = range(1, total);

  if (!needEllipsis) return pages;

  if (current <= breakpoint) {
    const from = 1;
    const to = max - 2;
    return [...range(from, to), '...', total];
  }

  if (current > total - breakpoint) {
    const from = total - (max - 3);
    const to = total;
    return [1, '...', ...range(from, to)];
  }

  const from = current - noOfSiblings;
  const to = current + noOfSiblings;
  return [1, '...', ...range(from, to), '...', total];
}