[page].js

//api/posts/[page].js

import {getSortedPostsData} from "../../lib/posts";


export default function (req, res) {
    const { page } = req.query
    const allPostsData = getSortedPostsData()
    const perPage = 9
    const totalPosts = allPostsData.length
    const totalPages = totalPosts / perPage
    const start = (page - 1) * perPage
    let end = start + perPage
    if (end > totalPosts) {
        end = totalPosts
    }

    res.status(200).json({
        currentPage: page,
        perPage: perPage,
        totalCount: totalPosts,
        pageCount: totalPages,
        start: start,
        end: end,
        posts: allPostsData.slice(start, end)
    })
}