/**
 * Attach ripple effect to an element.
 *
 * @param el Element to attach ripple effect
 * @param rippleColor Color of the ripple (in css color string)
 * @returns An object, use `cleanup()` to remove attached event listener,
 * use `rippleAt(x, y)` to manually invoke a ripple to create
 *
 * @example
 * ```js
 * const { cleanup, rippleAt } = ripple(
 *     document.querySelector("#el"),
 *     "rgb(from var(--md-sys-color-primary) r g b / 0.1)"
 * )
 * ```
 */
export declare function ripple(el: HTMLElement, rippleColor?: string): {
    cleanup: () => void;
    rippleAt: (rippleX: number, rippleY: number, autoRemove?: boolean) => (onFinish?: VoidFunction) => void;
} | undefined;