type T = any;
const TYPE = 't';
const MAP = 'm';
const SET = 's';
const VAL = 'v';
const stringify = (v: T) => JSON.stringify(v, replacer);
const parse = (v: string) => JSON.parse(v, reviver);
const isObject = (v: T) => typeof v === 'object' && v !== null;

const replacer = (_: T, v: T) =>
  v instanceof Map
    ? { [TYPE]: MAP, [VAL]: [...v] }
    : v instanceof Set
      ? { [TYPE]: SET, [VAL]: [...v] }
      : v;

const reviver = (_: T, v: T) =>
  isObject(v) && v[TYPE] === MAP
    ? new Map(v[VAL])
    : isObject(v) && v[TYPE] === SET
      ? new Set(v[VAL])
      : v;

/** Serializer is used to extend `JSON.stringify` and `JSON.parse` to support ES maps. */
export const JSONMap = { stringify, parse };