/**
 * Checks if the device has an active internet connection by making a fetch request to
 * 'https://ipv4.icanhazip.com/' and resolving the result.
 * The request will time out if the specified timeout duration is exceeded.
 *
 * @param {Object} options - The options object for the function.
 * @param {number} options.timeout - The timeout duration in milliseconds. If the request
 *                                    takes longer than this, it will be aborted.
 *
 * @returns {Promise<boolean>} A Promise that resolves to `true` if the device is online
 *                             (i.e., the fetch request is successful), or `false` if the device
 *                             is offline or the request fails or times out.
 */
export declare function isOnline(options: {
    timeout: number;
}): Promise<boolean>;