@safejs/serializer/src/serializers/map/map.spec.ts

Serializer is a superset of JSON that includes recursive objects, dates, regular expressions, functions and others which you also can expand by yourself

import { mapSerializer } from "./map";

describe("Map", () => {
    it("should serialize", () => {
        expect(mapSerializer.serialize(new Map())).toEqual([]);
    });
});