import { Binder } from "@ribajs/core";
export declare class ScrollspyClassBinder extends Binder<string, HTMLInputElement> {
    static key: string;
    private target?;
    private className?;
    private _onScroll;
    private onScroll;
    private _isInViewport;
    private isInViewport;
    bind(): void;
    routine(el: HTMLElement, targetSelector: string): void;
    unbind(): void;
}