Makes HTML anchors defined with ref work with HashRouters in react apps.

anchorsHashRouter.js

componentDidMount() {
    // Other initialization...
    // IMPORTANT: Put this after "document.body.classList.toggle"
    let hash = this.props.location.hash.replace('#', '');
    if (hash) {
        let node = ReactDOM.findDOMNode(this.refs[hash]);
        if (node) {
            node.scrollIntoView();
        }
    }
}

componentDidUpdate() {
    let hash = this.props.location.hash.replace('#', '');
    if (hash) {
        let node = ReactDOM.findDOMNode(this.refs[hash]);
        if (node) {
            node.scrollIntoView();
        }
    }
}

// Usage:
// /component-a
// <h3 ref='scroll_here'>Scroll to here</h3>
// ...
// /component-b
// <a href="/component-b#scroll_here">Scrolls to h3</a>