typings.d.ts

declare namespace Intl {
	function getCanonicalLocales(locales: string | string[] | undefined): string[];

	type Locale = string;
	type Locales = Locale[];
	type Type = "conjunction" | "disjunction" | "unit";
	type Style = "long" | "short" | "narrow";
	type LocaleMatcher = "lookup" | "best fit";

	interface ListFormatOptions {
		type: Type;
		style: Style;
		localeMatcher: LocaleMatcher;
	}

	interface ResolvedListFormatOptions {
		type: Type;
		style: Style;
		locale: Locale;
	}

	interface ElementPartition {
		type: "element";
		value: ListPartition[] | string;
	}

	interface ListPartitionBase {
		value: string;
	}

	interface LiteralPartition extends ListPartitionBase {
		type: "literal";
	}

	type ListPartition = ElementPartition | LiteralPartition;

	type ListPartitions = ReadonlyArray<ListPartition>;

	class ListFormat {
		constructor(locales?: Locale | Locales | undefined, options?: Partial<ListFormatOptions>);

		public static supportedLocalesOf(locales: Locale | Locales, options?: Intl.SupportedLocalesOptions | undefined): Locales;

		public format(list?: Iterable<string>): string;

		public formatToParts(list?: Iterable<string>): ListPartitions;

		public resolvedOptions(): ResolvedListFormatOptions;
	}
}