import library react js

JavaScript
// ---- REACT JS -----
// using
<link rel="shortcut icon" href="%PUBLIC_URL%/js/bootstrap.min.js"> </link>
<script src="%PUBLIC_URL%/js/bootstrap.min.js"> </script>

// public
// --- js 
// ------ bootstrap.min.js
// --- css 
// ------ bootstrap.min.css
class MainView extends Component {
  render() {
    // don't render anything
    return <div/>;
  },

  componentDidMount() {
    // find the DOM node for this component
    const node = ReactDOM.findDOMNode(this);

    // widget does stuff
    $(node).activateMyCoolWidget();

    // start a new React render tree with widget node
    ReactDOM.render(<div>{this.props.children}</div>, node);
  }
});
Source

Also in JavaScript: