Hydrate JSON dates

hydrate.ts

import { formatISO, parseISO } from "date-fns"

const dateRegex = /^[0-9]{4}(-[0-9]{2}){2}T[0-9]{2}(:[0-9]{2}){2}/
export function hydrate <T extends unknown>(obj: T): T
export function hydrate (obj: unknown): unknown {
  if (Array.isArray(obj)) return obj.map(hydrate)
  if (typeof obj !== 'object') return obj
  if (!obj) return obj

  return Object.entries(obj).reduce((hsh, [k, v]) => ({
    ...hsh,
    [k]: obj.constructor.name === 'object'
      ? hydrate(v)
      : typeof v === 'string' && dateRegex.exec(v)
        ? parseISO(v)
        : v
  }), {})
}

const replacer = (_: string, val: unknown) => {
  if (val instanceof Date) return formatISO(val)
  return val
}

export const dehydrate = (obj: unknown): string => {
  return JSON.stringify(obj, replacer)
}