With an application built using the create-react-app script the easiest way to include the component library is to call defineCustomElements(window) from the index.js file. Note that in this scenario applyPolyfills is needed if you are targeting Edge or IE11.

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import registerServiceWorker from './registerServiceWorker';

// test-component is the name of our made up Web Component that we have
// published to npm:
import { applyPolyfills, defineCustomElements } from 'test-components/loader';

ReactDOM.render(<App />, document.getElementById('root'));

applyPolyfills().then(() => {

Following the steps above will enable your web components to be used in React, however there are some additional complexities that must also be considered. describes them well.