export declare namespace DOM {
    function clean(e: HTMLElement): void;
    function appendClassName(e: HTMLElement, name: string): void;
    function removeClassName(e: HTMLElement, name: string): void;
    function setClassNames(e: HTMLElement, value: string | string[] | {
        [key: string]: boolean;
    }): void;
    function isInViewport(el: HTMLElement): boolean;
}