@safejs/serializer/src/serializers/nan/nan.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 { ConstantExtraSerializer } from "../../types";

export const nanSerializer: ConstantExtraSerializer<number> = {
    determine: (v) => Number.isNaN(v),
    deserialize: () => NaN,
};