React detect clicked element

react-handle-click-outside.ts

protected componentWillMount(): void {
    document.addEventListener('click', this.toggle);
}

protected componentWillUnmount(): void {
    document.removeEventListener('click', this.toggle);
}

private toggle = (event): void => {
    event.preventDefault();

    let component = ReactDOM.findDOMNode(this.refs['dropDown']);

    if (event.target === component || component.contains(event.target)) {
      // inside element
    } else {
      // outside element
    }
}