Context Menu in React

class ContextMenu extends React.Component {

    state = {
        visible: false,
    };

    componentDidMount() {
        document.addEventListener('contextmenu', this._handleContextMenu);
        document.addEventListener('click', this._handleClick);
        document.addEventListener('scroll', this._handleScroll);
    };

    componentWillUnmount() {
      document.removeEventListener('contextmenu', this._handleContextMenu);
      document.removeEventListener('click', this._handleClick);
      document.removeEventListener('scroll', this._handleScroll);
    }

    _handleContextMenu = (event) => {
        event.preventDefault();

        this.setState({ visible: true });

        const clickX = event.clientX;
        const clickY = event.clientY;
        const screenW = window.innerWidth;
        const screenH = window.innerHeight;
        const rootW = this.root.offsetWidth;
        const rootH = this.root.offsetHeight;

        const right = (screenW - clickX) > rootW;
        const left = !right;
        const top = (screenH - clickY) > rootH;
        const bottom = !top;

        if (right) {
            this.root.style.left = `${clickX + 5}px`;
        }

        if (left) {
            this.root.style.left = `${clickX - rootW - 5}px`;
        }

        if (top) {
            this.root.style.top = `${clickY + 5}px`;
        }

        if (bottom) {
            this.root.style.top = `${clickY - rootH - 5}px`;
        }
    };

    _handleClick = (event) => {
        const { visible } = this.state;
        const wasOutside = !(event.target.contains === this.root);

        if (wasOutside && visible) this.setState({ visible: false, });
    };

    _handleScroll = () => {
        const { visible } = this.state;

        if (visible) this.setState({ visible: false, });
    };

    render() {
        const { visible } = this.state;

        return(visible || null) && 
            <div ref={ref => {this.root = ref}} className="contextMenu">
                <div className="contextMenu--option">React Tutorials</div>               
                <div className="contextMenu--option">PHP Tutorials</div>
                <div className="contextMenu--separator" />
                <div className="contextMenu--option">All Tutorials</div>
            </div>
    };
}

.contextMenu {
    position: fixed;
    background: white;
    box-shadow: 0px 2px 10px #999999;

    &--option {
        padding: 6px 50px 5px 10px;
        min-width: 160px;
        cursor: default;
        font-size: 12px;
        &:hover {
            background: linear-gradient(to top, #555, #333);
            color: white;
        }

        &:active {
            color: #e9e9e9;
            background: linear-gradient(to top, #555, #444);
        }

        &__disabled {
            color: #999999;
            pointer-events: none;
        }
    }

    &--separator {
        width: 100%;
        height: 1px;
        background: #CCCCCC;
        margin: 0 0 0 0;
    }
}