Human readable IBAN formatting utility

HumanReadableIban.ts

// See: https://en.wikipedia.org/wiki/International_Bank_Account_Number
const IbanSpecialCountries = ['BI', 'EG', 'LY', 'SV'] as const;

// See: https://en.wikipedia.org/wiki/International_Bank_Account_Number
const IbanBreakpointsRegex = {
    // Breaks after every 4th character
    // Example: XXXX XXXX XXXX XXXX XXXX XX..
    default: /([a-z\d]{4}(?!$))/gi,

    // Burundi (4 5 5 11 2)
    // Example: BIXX XXXXX XXXXX XXXXXXXXXXX XX
    BI: /((?=(?:[a-z\d]{23}|[a-z\d]{18}|[a-z\d]{13}|[a-z\d]{2})$))/gi,

    // Egypt (no spaces)
    // Example: EGXXXXXXXXXXXXXXXXXXXXXXXXXXX
    // Uncomment this next line to format with spaces regardless
    // EG: /((?=(?:[a-z\d]{27}|[a-z\d]{25}|[a-z\d]{21}|[a-z\d]{17})$))/gi,

    // Libya (4 3 3 15)
    // Example: LYXX XXX XXX XXXXXXXXXXXXXXX
    LY: /((?=(?:[a-z\d]{21}|[a-z\d]{18}|[a-z\d]{15})$))/gi,

    // El Salvador (2 2 4 20)
    // Example: SV XX XXXX XXXXXXXXXXXXXXXXXXXX
    SV: /((?=(?:[a-z\d]{26}|[a-z\d]{24}|[a-z\d]{20})$))/gi,
} as const satisfies Partial<Record<(typeof IbanSpecialCountries)[number] | 'default'>>;

type IbanBreakpointsCountry = keyof typeof IbanBreakpointsRegex;

export function getHumanReadableIban(iban: string, useNonBreakingSpaces = true): string {
    const spaceSeparator = (useNonBreakingSpaces as any) !== false ? ' ' : ' ';
    const ibanWithoutSpaces = iban.replace(/\s+/g, '');

    let breakpointsCountry: IbanBreakpointsCountry = 'default';

    for (const country of IbanSpecialCountries) {
        if (RegExp(`^${country}`, 'i').test(ibanWithoutSpaces)) {
            breakpointsCountry = country as IbanBreakpointsCountry;
            break;
        }
    }

    return ibanWithoutSpaces.replace(IbanBreakpointsRegex[breakpointsCountry]!, `$1${spaceSeparator}`);
}