@sanity/orderable-document-list/src/helpers/initialRank.ts

Drag-and-drop Document Ordering without leaving the Editing surface

import {LexoRank} from 'lexorank'
import {NewItemPosition} from '../types'

// Use in initial value field by passing in the rank value of the last document
// If not value passed, generate a sensibly low rank
export default function initialRank(
  compareRankValue = ``,
  newItemPosition: NewItemPosition = 'after'
): string {
  const compareRank = compareRankValue ? LexoRank.parse(compareRankValue) : LexoRank.min()
  const rank =
    newItemPosition === 'before' ? compareRank.genPrev().genPrev() : compareRank.genNext().genNext()

  return rank.toString()
}