Use the Adyen Web npm package

[gcatanese]

Node Sample Integration should use the Adyen NPM packages, see https://docs.adyen.com/online-payments/web-drop-in

import AdyenCheckout from '@adyen/adyen-web';
import '@adyen/adyen-web/dist/adyen.css';

Currently the application embeds the resources in the HTML

<!-- Adyen JS from TEST environment (change to live for production)-->
  <script src="https://checkoutshopper-test.adyen.com/checkoutshopper/sdk/5.23.1/adyen.js"
            integrity="sha384-O0Q35c47I1ojd1zrD78yWAs+r5gytAjBC/sxwZqgQW5z9hDbAFM49z8SViprrDwm"
            crossorigin="anonymous"></script>

<!-- Adyen CSS from TEST environment (change to live for production)-->
  <link rel="stylesheet"
          href="https://checkoutshopper-test.adyen.com/checkoutshopper/sdk/5.23.1/adyen.css"
          integrity="sha384-y6jvSkH/EJ+EmVfUABibJST5Df3+PXlPuQveX3NigzwJmiNofEBsUXxbxoaEllaI"
          crossorigin="anonymous">

[jlengrand]

I've done a version of this for Paula (bare in mind it has no readme and is not complete) to fit closer to the docs actually : https://github.com/jlengrand/vanilla-js.

Thing is, then it requires adding a bundler to the toolchain. It's a good idea though.