pagination.js

const createPageOptions  = ((currentPage, pageCount) => {
  // from component properties
  const currentPage = currentPage

  // from Constants
  const NUM_OF_PAGE_OPTIONS = 7

  // useMemo with [currentPage] as deps
  const pageOptions = (() => {
    if (pageCount <= 0) return []
  
    const pages = new Array(pageCount).fill(1).map((e, i) => e + i)

    if (pageCount <= NUM_OF_PAGE_OPTIONS) return pages

    const firstPage = pages[0]
    const lastPage = pages[pages.length - 1]
    const pageOffset = Math.min(
      Math.max(
        Math.ceil(NUM_OF_PAGE_OPTIONS / 2), currentPage
      ) - Math.floor(NUM_OF_PAGE_OPTIONS / 2),
      pageCount - NUM_OF_PAGE_OPTIONS + 1
    )

    return [
        firstPage,
        ...[...pages].splice(pageOffset, NUM_OF_PAGE_OPTIONS - 2),
        lastPage
    ]
  })()

  return { pageOptions }
})