/**
 * Polyfill for requestAnimationFrame.
 *
 * @param {Function} callback The function to call when it's time.
 * @returns {number}
 */
export declare function requestAnimationFrame(callback: () => void): number;
/**
 * Polyfill for cancelAnimationFrame.
 *
 * @param {number} id The request Id, generated by `requestAnimationFrame`.
 */
export declare function cancelAnimationFrame(id: number): void;
/**
 * Schedules a low-priority task to run when the browser is idle. Uses `requestIdleCallback`
 * when available — with a timeout, so the task still progresses when the browser never idles —
 * and falls back to `requestAnimationFrame` otherwise.
 *
 * Use this for background work that nothing visual waits for (e.g. cache warming); unlike an
 * animation frame, an idle task does not compete with rendering while the user scrolls.
 *
 * @param {Function} callback The function to call during an idle period.
 * @param {number} [timeout=100] The maximum delay (in milliseconds) before the task is forced to run.
 * @returns {number}
 */
export declare function requestIdleTask(callback: () => void, timeout?: number): number;
/**
 * Cancels a task scheduled with `requestIdleTask`.
 *
 * @param {number} id The task Id, generated by `requestIdleTask`.
 */
export declare function cancelIdleTask(id: number): void;
/**
 * @returns {boolean}
 */
export declare function isTouchSupported(): boolean;
/**
 * Checks if the environment that the code runs in is a browser.
 *
 * @returns {boolean}
 */
export declare function isCSR(): boolean;
/**
 * Get string comparison function for sorting purposes. It supports multilingual string comparison base on Internationalization API.
 *
 * @param {string} [language] The language code used for phrases sorting.
 * @param {object} [options] Additional options for sort comparator.
 * @returns {*}
 */
export declare function getComparisonFunction(language?: string, options?: object): (a: string, b: string) => number;