pagination. При получаем пагинацию для страниц

get_navigation.js

function get_navigation (page, post_number, total_post, number_link)
	{

	let number_pages = (total_post / post_number)

	if ((total_post % post_number) != 0)
		{
		number_pages++
		}

	if (total_post < post_number || page > number_pages)
		{
		return false
		}

	let result = {}
	result.next = []
	result.previous = []

	if (page != 1)
		{
		result.end = 1
		result.previous_page = page - 1
		}

	if (page > number_link + 1)
		{
		for (let i = page - number_link; i < page; i++)
			{
			result.previous.push(i)
			}
		}
	else
		{
		for (let i = 1; i < page; i++)
			{
			result.previous.push(i)
			}
		}

	result.current = page

	if (page + number_link < number_pages)
		{
		for (let i = page + 1; i <= page + number_link; i++)
			{
			result.next.push(i)
			}
		}
	else
		{
		for (let i = page + 1; i <= number_pages; i++)
			{
			result.next.push(i)
			}
		}

	if (page != number_pages)
		{
		result.next_page = page + 1
		result.end = number_pages
		}

	return result
	}

get_navigation.php

<?php 
/**
	 * @param int $page текущая страница
	 * @param int $post_number количество записей на странице 
	 * @param int $total_post всего записей
	 * @param int $number_link количество ссылок слева и справа (например, если нужно две ссылки, то у страницы 1, будет 1 2 3)
	 * @return array|false
	 */
	public function get_navigation($page, $post_number, $total_post, $number_link)
		{

		$number_pages = (int)($totalPost / $postNumber);

        if (($totalPost % $postNumber) != 0) {
            $number_pages++;
        }

        if ($totalPost < $postNumber || $page > $number_pages) {
            return FALSE;
        }

        $result = array();

        if ($page != 1) {
            $result['start'] = 1;
            $result['previous_page'] = $page - 1;
        }

        if ($page > $numberLink + 1) {
            for ($i = $page - $numberLink; $i < $page; $i++) {
                $result['previous'][] = $i;
            }
        } else {
            for ($i = 1; $i < $page; $i++) {
                $result['previous'][] = $i;
            }
        }

        $result['current'] = $page;

        if ($page + $numberLink < $number_pages) {
            for ($i = $page + 1; $i <= $page + $numberLink; $i++) {
                $result['next'][] = $i;
            }
        } else {
            for ($i = $page + 1; $i <= $number_pages; $i++) {
                $result['next'][] = $i;
            }
        }

        if ($page != $number_pages) {
            $result['next_page'] = $page + 1;
            $result['end'] = $number_pages;
        }

        return $result;
		}

результат

print_r(get_navigation(7, 2, 100, 3));
Array
(
    [start] => 1
    [previous_page] => 6
    [previous] => Array
        (
            [0] => 4
            [1] => 5
            [2] => 6
        )

    [current] => 7
    [next] => Array
        (
            [0] => 8
            [1] => 9
            [2] => 10
        )

    [next_page] => 8
    [end] => 50
)

get_navigation(1, 10, 99, 3);
Array
(
    [current] => 1
    [next] => Array
        (
            [0] => 2
            [1] => 3
            [2] => 4
        )

    [next_page] => 2
    [end] => 10
)

get_navigation(5, 10, 99, 1);
Array
(
    [start] => 1
    [previous_page] => 4
    [previous] => Array
        (
            [0] => 4
        )

    [current] => 5
    [next] => Array
        (
            [0] => 6
        )

    [next_page] => 6
    [end] => 10
)