JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://fb.me/react-with-addons-15.1.0.js"></script>
<script src="https://fb.me/react-dom-15.1.0.js"></script>
<script src="https://www.paypalobjects.com/api/checkout.js" async></script>
<div id="View"></div>

Babel + JSX

class PayPalButton extends React.Component {
  constructor() {
    super();
    // you can take this value from a config.js module for example.
    this.merchantId = '6XF3MPZBZV6HU';
  }

  componentDidMount() {
    let container = this.props.id;
    let merchantId = this.merchantId;
    window.paypalCheckoutReady = function() {
      paypal.checkout.setup(merchantId, {
        locale: 'en_US',
        environment: 'sandbox',
        container: container,
      });
    }
  }

  render() {
    return(
      <a id={this.props.id} href="/checkout" />
    );
  }
}

ReactDOM.render(<PayPalButton id="button" />, document.getElementById('View'));