[ReactJS] Detect Scrolls To Bottom

[ReactJS] Detect Scrolls To Bottom

constructor(props) {
        super(props);
        this.state = {
            height: window.innerHeight,
            message: 'not at bottom'
        };
        this.handleScroll = this.handleScroll.bind(this);
    }
    handleScroll() {
        const windowHeight = "innerHeight" in window ? window.innerHeight : document.documentElement.offsetHeight;
        const body = document.body;
        const html = document.documentElement;
        const docHeight = Math.max(body.scrollHeight, body.offsetHeight, html.clientHeight, html.scrollHeight, html.offsetHeight);
        const windowBottom = windowHeight + window.pageYOffset;
        if (windowBottom >= docHeight) {
            this.setState({
                message: 'bottom reached'
            });
        } else {
            this.setState({
                message: 'not at bottom'
            });
        }
    }

    componentDidMount() {
        window.addEventListener("scroll", this.handleScroll);
    }

    componentWillUnmount() {
        window.removeEventListener("scroll", this.handleScroll);
    }