How to authenticate CloudKit JS in react JS or React-Redux JS

I am very new to web development. I have downloaded the CloudKit JS & adding in index.html in script tag. And I made sure it loads before my react-redux bundle JS.

  <script src="/cloudkit.js"></script>
  <script src="/bundle.js"></script>

I have made single class component & I am running authentication on component did mount as follows.

componentWillMount() {
CloudKit.configure({
  containers: [{
    containerIdentifier: '<container ID>',
    apiToken: '<secret api token>',
    environment: 'development'
  }]
});
var container = CloudKit.getDefaultContainer();
container.setUpAuth().then(function(userInfo) {
  if(userInfo) {
            console.log(userInfo);
        } else {
            console.log('need to login');
        }
    });
}

Then I get following error How do I authenticate in React with CloudKit JS?

The 421 is expected: basically this is CloudKit JS checking with the server if the user is signed in. You should still see your log statement 'need to login'.

You should also:

• Provide dom elements where the signIn / signOut buttons should to be rendered to.
• Call container.setUpAuth in componentDidMount instead of componentWillMount (the dom elements for the sign in buttons have to exist when you call this method).

Sample code (https://jsfiddle.net/byb7ha0o/4/):

CloudKit.configure({
  containers: [{
    containerIdentifier: '<container>',
    apiToken: '<token>',
    environment: 'development'
  }]
});
const container = CloudKit.getDefaultContainer();

class HelloCloudKitJS extends React.Component {

  constructor() {
    super();
    this.state = {
        userInfo: null
    }
  }

  componentDidMount() {
    container
      .setUpAuth()
        .then(userInfo => {
        if(userInfo) {
            this.setState({userInfo: userInfo});
          return;
        }
        container
          .whenUserSignsIn()
            .then(userInfo => {
                this.setState({userInfo: userInfo})
          })  
      })
  }

  render() {
    return <div>
      <div>
        <div id="apple-sign-in-button"></div>
        <div id="apple-sign-out-button"></div>
      </div>
    </div>;
  }
}

ReactDOM.render(
  <HelloCloudKitJS />,
  document.getElementById('container')
);