resolve-accept-language/lib/cjs/index.d.ts

Resolve the preferred locale based on the value of an `Accept-Language` HTTP header.

/** The type of matches. */
export type MatchType = 'locale' | 'languageSpecificLocale' | 'language' | 'relatedLocale' | 'languageCountry' | 'country' | 'defaultLocale';
/** The type of matches enumeration. */
export declare const MATCH_TYPES: {
    readonly [K in MatchType]: K;
};
/** Type to normalize the locale format. */
export type NormalizeLocale<Remainder extends string> = Remainder extends `${infer LanguageCode}-${infer CountryCode}` ? `${Lowercase<LanguageCode>}-${Uppercase<CountryCode>}` : Remainder;
/** Additional options to apply. */
type Options<WithMatchType extends boolean | undefined> = {
    /** Should the match type be returned? */
    returnMatchType?: WithMatchType;
    /** Should the country of the locale be used for matching? */
    matchCountry?: boolean;
};
type Result<Locales extends readonly string[], WithMatchType extends boolean | undefined> = WithMatchType extends true ? {
    /** The best locale match. */
    match: NormalizeLocale<Locales[number]>;
    /** The type of match. */
    matchType: MatchType;
} : NormalizeLocale<Locales[number]>;
/**
 * Resolve the preferred locale from an HTTP `Accept-Language` header.
 *
 * All locale identifiers provided as parameters must following the BCP 47 `language`-`country` (case insensitive).
 *
 * @param acceptLanguageHeader - The value of an HTTP request `Accept-Language` header (also known as a "language priority list").
 * @param locales - An array of locale identifiers that must include the default locale. The order will be used for matching where
 * the first identifier will be more likely to be matched than the last identifier.
 * @param defaultLocale - The default locale identifier when no match is found.
 * @param options - Additional options to apply.
 *
 * @returns Either the best locale match or a match object, depending on options.
 *
 * @example
 * // returns 'fr-CA'
 * resolveAcceptLanguage(
 *   'fr-CA;q=0.01,en-CA;q=0.1,en-US;q=0.001',
 *   ['en-US', 'fr-CA'],
 *   'en-US'
 * )
 */
export declare const resolveAcceptLanguage: <Locales extends readonly string[], WithMatchType extends boolean | undefined = undefined>(acceptLanguageHeader: string, locales: Locales, defaultLocale: Locales[number], options?: Options<WithMatchType>) => Result<Locales, WithMatchType>;
export {};