messageformat-number-skeleton/lib/numberformat/locales.js

A parser & formatter for ICU NumberFormat skeleton strings & patterns

/**
 * Add
 * {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl#Locale_identification_and_negotiation | numbering-system tags}
 * to locale identifiers
 *
 * @internal
 */
export function getNumberFormatLocales(locales, { numberingSystem }) {
    if (!Array.isArray(locales))
        locales = [locales];
    return numberingSystem
        ? locales
            .map(lc => {
            const ext = lc.indexOf('-u-') === -1 ? 'u-nu' : 'nu';
            return `${lc}-${ext}-${numberingSystem}`;
        })
            .concat(locales)
        : locales;
}