Suggestion: functional implementation

[JurJean]

I want to suggest to use a more functional approach for the library. I created an example of this for PostalCode:

type PostalCodeInfo = {
    pattern: RegExp;
    search?: RegExp | undefined;
    replace?: string | undefined;
};

function createPostalCodeInfo(
    pattern: RegExp,
    search?: RegExp | undefined,
    replace?: string | undefined
): PostalCodeInfo {
    return {
        pattern,
        search,
        replace
    };
}

const PostalCodeInfos = {
    AD: createPostalCodeInfo(/^(AD)?[1-7][0-9]{2}$/, /^(AD)?(...)$/, 'AD-$2'),
    AF: createPostalCodeInfo(/^(0[1-9]|[1-3][0-9]|4[0-3])([0-9]{2})(?<!00)$/),
    AI: createPostalCodeInfo(/^(AI)?2640$/, /^.+$/, 'AI-2640'),
    AL: createPostalCodeInfo(/^[1-9][0-9]{3}$/),
    AM: createPostalCodeInfo(/^[0-4][0-9]{3}$/),
    AR: createPostalCodeInfo(/^[A-Z][1-9][0-9]{3}[A-Z]{3}$/, /^(.)(....)(...)$/, '$1 $2 $3'),
    AS: createPostalCodeInfo(/^9[0-9]{4}([0-9]{4})?$/, /^(.{5})(....)?$/, '$1 $2'),
    AT: createPostalCodeInfo(/^[1-9][0-9]{3}$/),
    AU: createPostalCodeInfo(/^(0[89]|[1-9][0-9])[0-9]{2}$/),
    AX: createPostalCodeInfo(/^22[0-9]{3}$/, /^(..)(...)$/, '$1-$2'),
    AZ: createPostalCodeInfo(/^(AZ)?[0-9]{4}$/, /^(AZ)?(....)$/, 'AZ-$2'),
    BA: createPostalCodeInfo(/^[0-9]{5}$/),
    BB: createPostalCodeInfo(/^(BB)?[0-9]{5}$/, /^(BB)?(.{5})$/, 'BB-$2'),
    BD: createPostalCodeInfo(/^[0-9]{4}$/),
    BE: createPostalCodeInfo(/^[1-9][0-9]{3}$/),
    BG: createPostalCodeInfo(/^[1-9][0-9]{3}$/),
    BH: createPostalCodeInfo(/^(1[0-2]|[1-9])[0-9]{2}$/),
    BL: createPostalCodeInfo(/^977[0-9]{2}$/),
    BM: createPostalCodeInfo(/^[A-Z]{2}([A-Z0-9]{2})?$/, /^(..)(..)$/, '$1 $2'),
    BN: createPostalCodeInfo(/^[A-Z]{2}[0-9]{4}$/),
    BO: createPostalCodeInfo(/^[0-9]{4}$/),
    BR: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{6}$/, /^(.{5})(...)$/, '$1-$2'),
    BT: createPostalCodeInfo(/^[0-9]{3}$/),
    BY: createPostalCodeInfo(/^[0-9]{6}$/),
    CA: createPostalCodeInfo(/^[ABCEGHJKLMNPRSTVXY][0-9][ABCEGHJKLMNPRSTVWXYZ][0-9][ABCEGHJKLMNPRSTVWXYZ][0-9]$/, /^(...)(...)$/, '$1 $2'),
    CC: createPostalCodeInfo(/^[0-9]{4}$/),
    CH: createPostalCodeInfo(/^[1-9][0-9]{3}$/),
    CL: createPostalCodeInfo(/^[0-9]{7}$/, /^(...)(....)$/, '$1-$2'),
    CN: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{4}$/),
    CO: createPostalCodeInfo(/^[0-9]{6}$/),
    CR: createPostalCodeInfo(/^[0-9]{5}$/),
    CU: createPostalCodeInfo(/^(CP)?[0-9]{5}$/, /^(..)?(.{5})$/, 'CP$2'),
    CV: createPostalCodeInfo(/^[0-9]{4}$/),
    CX: createPostalCodeInfo(/^[0-9]{4}$/),
    CY: createPostalCodeInfo(/^[1-9][0-9]{3}$/),
    CZ: createPostalCodeInfo(/^[1-7][0-9]{4}$/, /^(...)(..)$/, '$1 $2'),
    DE: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{3}$/),
    DK: createPostalCodeInfo(/^(DK)?[1-9][0-9]{3}$/, /^(DK)?(....)$/, 'DK-$2'),
    DZ: createPostalCodeInfo(/^[0-9]{5}$/),
    EC: createPostalCodeInfo(/^[0-9]{6}$/),
    EE: createPostalCodeInfo(/^[0-9]{5}$/),
    EG: createPostalCodeInfo(/^[1-9][0-9]{4}$/),
    ES: createPostalCodeInfo(/^((0[1-9])|([1-4][0-9])|(5[012]))[0-9]{3}$/),
    ET: createPostalCodeInfo(/^[0-9]{4}$/),
    FI: createPostalCodeInfo(/^[0-9]{5}$/, /^(..)(...)$/, '$1-$2'),
    FK: createPostalCodeInfo(/^FIQQ1ZZ$/, /^.+$/, 'FIQQ 1ZZ'),
    FM: createPostalCodeInfo(/^9694[1234]([0-9]{4})?$/, /^(.{5})(....)$/, '$1-$2'),
    FO: createPostalCodeInfo(/^(FO)?[1-9][0-9]{2}$/, /^(FO)?(...)$/, 'FO-$2'),
    FR: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{3}$/),
    GA: createPostalCodeInfo(/^[0-9]{4}$/, /^(..)(..)$/, '$1 $2'),
    GB: createPostalCodeInfo(/^[A-Z]?[A-Z][0-9][A-Z0-9]?[0-9][A-Z]{2}$/, /^(.+)(...)$/, '$1 $2'),
    GE: createPostalCodeInfo(/^[0-9]{4}$/),
    GF: createPostalCodeInfo(/^973[0-9]{2}$/),
    GG: createPostalCodeInfo(/^(GY)?[0-9]{2,3}[A-Z]{2}$/, /^(GY)?(...?)(...)$/, 'GY$2 $3'),
    GI: createPostalCodeInfo(/^GX111AA$/, /^.+$/, 'GX11 1AA'),
    GL: createPostalCodeInfo(/^(GL)?39[0-9]{2}$/, /^(GL)?(....)$/, 'GL-$2'),
    GP: createPostalCodeInfo(/^971[0-9]{2}$/),
    GR: createPostalCodeInfo(/^[1-9][0-9]{4}$/, /^(...)(..)$/, '$1 $2'),
    GS: createPostalCodeInfo(/^SIQQ1ZZ$/, /^.+$/, 'SIQQ 1ZZ'),
    GT: createPostalCodeInfo(/^[0-9]{5}$/),
    GU: createPostalCodeInfo(/^969([12][0-9]|3[0-3])([0-9]{4})?$/, /^(.{5})(....)$/, '$1-$2'),
    GW: createPostalCodeInfo(/^[0-9]{4}$/),
    HM: createPostalCodeInfo(/^[0-9]{4}$/),
    HN: createPostalCodeInfo(/^[0-9]{5}$/),
    HR: createPostalCodeInfo(/^[0-9]{5}$/),
    HT: createPostalCodeInfo(/^[0-9]{4}$/),
    HU: createPostalCodeInfo(/^[1-9][0-9]{3}$/),
    ID: createPostalCodeInfo(/^[1-9][0-9]{4}$/),
    IL: createPostalCodeInfo(/^[0-9]{7}$/),
    IM: createPostalCodeInfo(/^(IM)?[0-9]{2,3}[A-Z]{2}$/, /^(IM)?(..?)(...)$/, 'IM$2 $3'),
    IN: createPostalCodeInfo(/^[1-9][0-9]{5}$/),
    IO: createPostalCodeInfo(/^BBND1ZZ$/, /^.+$/, 'BBND 1ZZ'),
    IQ: createPostalCodeInfo(/^[13456][0-9]{4}$/),
    IR: createPostalCodeInfo(/^[0-9]{10}$/, /^(.{5})(.{5})$/, '$1-$2'),
    IS: createPostalCodeInfo(/^[0-9]{3}$/),
    IT: createPostalCodeInfo(/^([0-9]{3})(?<!000)[0-9]{2}$/),
    JE: createPostalCodeInfo(/^(JE)?[0-9]{2,3}[A-Z]{2}$/, /^(JE)?(...?)(...)$/, 'JE$2 $3'),
    JO: createPostalCodeInfo(/^[0-9]{5}$/),
    JP: createPostalCodeInfo(/^[0-9]{7}$/, /^(....)(...)$/, '$1-$2'),
    KG: createPostalCodeInfo(/^[0-9]{6}$/),
    KH: createPostalCodeInfo(/^[0-9]{5}$/),
    KR: createPostalCodeInfo(/^[1-7][0-9]{5}$/, /^(...)(...)$/, '$1-$2'),
    KY: createPostalCodeInfo(/^(KY)?[0-9]{5}$/, /^(KY)?(.)(....)$/, 'KY$2-$3'),
    KZ: createPostalCodeInfo(/^[0-9]{6}$/),
    LA: createPostalCodeInfo(/^[0-9]{5}$/),
    LB: createPostalCodeInfo(/^[0-9]{8}$/, /^(....)(....)$/, '$1 $2'),
    LI: createPostalCodeInfo(/^94(8[5-9]|9[0-8])$/),
    LK: createPostalCodeInfo(/^[0-9]{5}$/),
    LR: createPostalCodeInfo(/^[0-9]{4}$/),
    LS: createPostalCodeInfo(/^[0-9]{3}$/),
    LT: createPostalCodeInfo(/^(LT)?[0-9]{5}$/, /^(LT)?(.{5})$/, 'LT-$2'),
    LU: createPostalCodeInfo(/^[0-9]{4}$/),
    LV: createPostalCodeInfo(/^(LV)?[0-9]{4}$/, /^(LV)?(....)$/, 'LV-$2'),
    LY: createPostalCodeInfo(/^[0-9]{5}$/),
    MA: createPostalCodeInfo(/^[1-9][0-9]{4}$/, /^(..)(...)$/, '$1 $2'),
    MC: createPostalCodeInfo(/^(MC)?980[0-9]{2}$/),
    MD: createPostalCodeInfo(/^(MD)?[0-9]{4}$/, /^(MD)?(....)$/, 'MD-$2'),
    ME: createPostalCodeInfo(/^8[145][0-9]{3}$/),
    MF: createPostalCodeInfo(/^978[0-9]{2}$/),
    MG: createPostalCodeInfo(/^[0-9]{3}$/),
    MH: createPostalCodeInfo(/^969[67][0-9]([0-9]{4})?$/, /^(.{5})(....)$/, '$1-$2'),
    MK: createPostalCodeInfo(/^[0-9]{4}$/),
    MM: createPostalCodeInfo(/^[0-9]{5}$/),
    MN: createPostalCodeInfo(/^[0-9]{5}$/),
    MP: createPostalCodeInfo(/^9695[012]([0-9]{4})?$/, /^(.{5})(....)$/, '$1-$2'),
    MQ: createPostalCodeInfo(/^972[0-9]{2}$/),
    MT: createPostalCodeInfo(/^[A-Z]{3}[0-9]{4}$/, /^(...)(....)$/, '$1 $2'),
    MX: createPostalCodeInfo(/^[0-9]{5}$/),
    MY: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{3}$/),
    MZ: createPostalCodeInfo(/^[0-9]{4}$/),
    NA: createPostalCodeInfo(/^9[0-2][0-9]{3}$/),
    NC: createPostalCodeInfo(/^988[0-9]{2}$/),
    NE: createPostalCodeInfo(/^[0-9]{4}$/),
    NF: createPostalCodeInfo(/^[0-9]{4}$/),
    NG: createPostalCodeInfo(/^[0-9]{6}$/),
    NI: createPostalCodeInfo(/^[0-9]{5}$/),
    NL: createPostalCodeInfo(/^[1-9][0-9]{3}([A-Z]{2})(?<!SS|SA|SD)$/, /^(....)(..)$/, '$1 $2'),
    NO: createPostalCodeInfo(/^[0-9]{4}$/),
    NP: createPostalCodeInfo(/^[0-9]{5}$/),
    NZ: createPostalCodeInfo(/^[0-9]{4}$/),
    OM: createPostalCodeInfo(/^[0-9]{3}$/),
    PA: createPostalCodeInfo(/^[0-9]{6}$/),
    PE: createPostalCodeInfo(/^[0-9]{5}$/),
    PF: createPostalCodeInfo(/^987[0-9]{2}$/),
    PG: createPostalCodeInfo(/^[0-9]{3}$/),
    PH: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{2}$/),
    PK: createPostalCodeInfo(/^[1-9][0-9]{4}$/),
    PL: createPostalCodeInfo(/^[0-9]{5}$/, /^(..)(...)$/, '$1-$2'),
    PM: createPostalCodeInfo(/^97500$/),
    PN: createPostalCodeInfo(/^PCRN1ZZ$/, /^.+$/, 'PCRN 1ZZ'),
    PR: createPostalCodeInfo(/^[0-9]{5}$/),
    PS: createPostalCodeInfo(/^[0-9]{5}$/),
    PT: createPostalCodeInfo(/^[1-9][0-9]{6}$/, /^(....)(...)$/, '$1 $2'),
    PW: createPostalCodeInfo(/^96940([0-9]{4})?$/, /^(.{5})(....)$/, '$1-$2'),
    PY: createPostalCodeInfo(/^[0-9]{4}$/),
    RE: createPostalCodeInfo(/^974[0-9]{2}$/),
    RO: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{4}$/),
    RS: createPostalCodeInfo(/^[123][0-9]{4}$/),
    RU: createPostalCodeInfo(/^[1-6][0-9]{5}$/),
    SA: createPostalCodeInfo(/^[0-9]{5}([0-9]{4})?$/, /^(.{5})(....)$/, '$1-$2'),
    SD: createPostalCodeInfo(/^[0-9]{5}$/),
    SE: createPostalCodeInfo(/^[1-9][0-9]{4}$/, /^(...)(..)$/, '$1 $2'),
    SG: createPostalCodeInfo(/^[0-9]{6}$/),
    SH: createPostalCodeInfo(/^STHL1ZZ$/, /^.+$/, 'STHL 1ZZ'),
    SI: createPostalCodeInfo(/^(SI)?[0-9]{4}$/, /^(SI)?(....)$/, 'SI-$2'),
    SK: createPostalCodeInfo(/^[0-9]{5}$/, /^(...)(..)$/, '$1 $2'),
    SM: createPostalCodeInfo(/^4789[0-9]$/),
    SN: createPostalCodeInfo(/^(CP)?[0-9]{5}$/, /^(..)?(.{5})$/, 'CP$2'),
    SV: createPostalCodeInfo(/^01101$/),
    SZ: createPostalCodeInfo(/^[HLMS][0-9]{3}$/),
    TC: createPostalCodeInfo(/^TKCA1ZZ$/, /^.+$/, 'TKCA 1ZZ'),
    TD: createPostalCodeInfo(/^[0-9]{5}$/),
    TH: createPostalCodeInfo(/^[1-9][0-9]{4}$/),
    TJ: createPostalCodeInfo(/^[0-9]{6}$/),
    TM: createPostalCodeInfo(/^[0-9]{6}$/),
    TN: createPostalCodeInfo(/^[0-9]{4}$/),
    TR: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{3}$/),
    TT: createPostalCodeInfo(/^[0-9]{6}$/),
    TW: createPostalCodeInfo(/^[1-9][0-9]{4}$/),
    UA: createPostalCodeInfo(/^([0-9]{2})(?<!00)[0-9]{3}$/),
    US: createPostalCodeInfo(/^[0-9]{5}([0-9]{4})?$/, /^(.{5})(....)$/, '$1-$2'),
    UY: createPostalCodeInfo(/^[0-9]{5}$/),
    VA: createPostalCodeInfo(/^00120$/),
    VC: createPostalCodeInfo(/^(VC)?[0-9]{4}$/, /^(VC)?(....)$/, 'VC$2'),
    VE: createPostalCodeInfo(/^[0-9]{4}[A-Z]?$/, /^(....)(.)$/, '$1-$2'),
    VG: createPostalCodeInfo(/^(VG)?11[0-6][0-9]$/, /^(VG)?(....)$/, 'VG$2'),
    VI: createPostalCodeInfo(/^008[1-5][0-9]([0-9]{4})?$/, /^(.{5})(....)$/, '$1-$2'),
    VN: createPostalCodeInfo(/^[0-9]{6}$/),
    WF: createPostalCodeInfo(/^986[0-9]{2}$/),
    XK: createPostalCodeInfo(/^[1-7][0-9]{4}$/),
    YT: createPostalCodeInfo(/^976[0-9]{2}$/),
    ZA: createPostalCodeInfo(/^([0-9]{4})(?<!0000)$/),
    ZM: createPostalCodeInfo(/^[0-9]{5}$/),
};

export type PostalCode = string;

export function formatPostalCode(code: PostalCode, country: keyof typeof PostalCodeInfos): string {
    if (!validatePostalCode(code, country)) {
        throw new Error(`Not a valid postal code for country ${country}`);
    }
    
    const info = PostalCodeInfos[country];

    return info.search === undefined
        ? code
        : code.replace(this.search, this.replace);
}

export function validatePostalCode(code: PostalCode | undefined | null, country: keyof typeof PostalCodeInfos): code is PostalCode {
    if (code === '' || code === null || code === undefined) {
        return false;
    }

    const info = PostalCodeInfos[country];

    return info.pattern.test(code);
}

export function normalizePostalCode(value: string): PostalCode {
    return value
        .replace(/[_- \.]/g, '')
        .toUpperCase();
}

It will have these benefits:

• No need for serialization (toJson/fromJson) or parsing.
• Easy integration into validation frameworks, just pass the validatePostalCode function.
• Easy integration into form frameworks, since only simple types are used. No need to transform to/from an object if the form value changes.
• Better tree-shaking.