export declare function isExternalURL(url: URL): boolean;
/**
 * Given a link href, constructs the URL that should be prefetched. Returns null
 * in cases where prefetching should be disabled, like external URLs, or
 * during development.
 * @param href The href passed to <Link>, router.prefetch(), or similar
 * @returns A URL object to prefetch, or null if prefetching should be disabled
 */
export declare function createPrefetchURL(href: string): URL | null;