pagination-helpers

Zero-dependency pagination math primitives.

Three small, pure functions for computing the page count, the page range to render (with ellipses), and the "Showing X to Y of Z" display range from page/perPage/total. No React, no router, no styling — just the math, so each consumer can build their own pagination component on top.

Features

• Zero dependencies
• Pure functions — no state, no I/O, trivially testable
• Atomic primitives: pick the function you need, ignore the rest
• Full TypeScript support
• ESM and CommonJS builds

Installation

npm install pagination-helpers
# or
pnpm add pagination-helpers
# or
yarn add pagination-helpers

Quick Start

import {
  getPageCount,
  getPageRange,
  getDisplayRange,
} from 'pagination-helpers'

const page = 10
const perPage = 10
const total = 195

getPageCount({ total, perPage })
// 20

getPageRange({ page, pageCount: 20 })
// [1, 'ellipsis-before', 8, 9, 10, 11, 12, 'ellipsis-after', 20]

getDisplayRange({ page, perPage, total })
// { from: 91, to: 100 }

API

getPageCount({ total, perPage })

Returns the number of pages. Math.ceil(total / perPage). Returns 0 when total is 0.

getPageCount({ total: 50, perPage: 10 }) // 5
getPageCount({ total: 47, perPage: 10 }) // 5
getPageCount({ total: 0, perPage: 10 })  // 0

getPageRange({ page, pageCount, pagesAroundCurrent?, pagesAtEdges? })

Returns the sequence of page numbers (with ellipses) to render in a pagination control.

The output always starts with the first pagesAtEdges pages and ends with the last pagesAtEdges pages, with pagesAroundCurrent pages on either side of page. Gaps between these groups become 'ellipsis-before' (gap on the left of page) or 'ellipsis-after' (gap on the right of page). When a gap consists of a single missing page, that page is included in the output instead of an ellipsis.

| Option | Default | Meaning | | --- | --- | --- | | pagesAroundCurrent | 2 | Pages to show on each side of page | | pagesAtEdges | 1 | Pages to always show at the start and end |

Returns Array<number | 'ellipsis-before' | 'ellipsis-after'>. Empty when pageCount is 0.

// Both ellipses
getPageRange({ page: 10, pageCount: 20 })
// [1, 'ellipsis-before', 8, 9, 10, 11, 12, 'ellipsis-after', 20]

// Single-page gaps fill in instead of ellipsis
getPageRange({ page: 5, pageCount: 10 })
// [1, 2, 3, 4, 5, 6, 7, 'ellipsis-after', 10]

// All pages fit
getPageRange({ page: 3, pageCount: 5 })
// [1, 2, 3, 4, 5]

// Custom knobs
getPageRange({ page: 10, pageCount: 20, pagesAroundCurrent: 1 })
// [1, 'ellipsis-before', 9, 10, 11, 'ellipsis-after', 20]

getPageRange({ page: 10, pageCount: 20, pagesAtEdges: 2 })
// [1, 2, 'ellipsis-before', 8, 9, 10, 11, 12, 'ellipsis-after', 19, 20]

The two ellipsis variants let consumers give them stable React keys without falling back to the array index.

getDisplayRange({ page, perPage, total })

Returns the 1-based item range shown on the current page — { from, to }. Useful for "Showing X to Y of Z results" labels.

Returns { from: 0, to: 0 } when there are no items to show on the current page (total is 0, or page is past the last page).

getDisplayRange({ page: 1, perPage: 10, total: 47 }) // { from: 1, to: 10 }
getDisplayRange({ page: 5, perPage: 10, total: 47 }) // { from: 41, to: 47 }
getDisplayRange({ page: 1, perPage: 10, total: 0 })  // { from: 0, to: 0 }

Edge cases

The package does no input validation or clamping — it computes honest math from whatever you pass in. Callers are responsible for sane inputs (page >= 1, perPage >= 1, total >= 0). The one edge case worth highlighting:

• total === 0 (empty list): getPageCount returns 0, getPageRange returns [], getDisplayRange returns { from: 0, to: 0 }. Callers typically render an empty state instead of pagination, and pages.length > 0 is the natural condition.

Worked example

A minimal pagination component built from the three primitives:

import {
  getPageCount,
  getPageRange,
  getDisplayRange,
} from 'pagination-helpers'

type Props = { page: number; perPage: number; total: number }

function Pagination({ page, perPage, total }: Props) {
  const pageCount = getPageCount({ total, perPage })
  if (pageCount === 0) return null

  const pages = getPageRange({ page, pageCount })
  const { from, to } = getDisplayRange({ page, perPage, total })

  return (
    <div>
      <p>
        Showing {from} to {to} of {total} results
      </p>
      <nav aria-label="Pagination">
        {pages.map((item) => {
          if (item === 'ellipsis-before' || item === 'ellipsis-after') {
            return <span key={item}>…</span>
          }
          return (
            <a
              key={item}
              href={`?page=${item}`}
              aria-current={item === page ? 'page' : undefined}
            >
              {item}
            </a>
          )
        })}
      </nav>
    </div>
  )
}

Types

import type { PageRangeItem } from 'pagination-helpers'
// number | 'ellipsis-before' | 'ellipsis-after'

License

MIT