/**
 * @license chowa v1.1.3
 *
 * Copyright (c) Chowa Techonlogies Co.,Ltd.(http://www.chowa.cn).
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
import * as React from 'react';
import * as PropTypes from 'prop-types';
export interface BackTopProps {
    className?: string;
    style?: React.CSSProperties;
    target?: () => HTMLElement | Window;
}
export interface BackTopState {
    visible: boolean;
    rolling: boolean;
}
declare class BackTop extends React.PureComponent<BackTopProps, BackTopState> {
    static propTypes: {
        className: PropTypes.Requireable<string>;
        style: PropTypes.Requireable<object>;
        target: PropTypes.Requireable<(...args: any[]) => any>;
    };
    static defaultProps: {
        target: () => Window & typeof globalThis;
    };
    constructor(props: BackTopProps);
    private getScrollTop;
    private setScrollTop;
    private onScrollHandler;
    componentDidMount(): void;
    componentWillUnmount(): void;
    private onClickHandler;
    render(): JSX.Element;
}
export default BackTop;