JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://js.chargebee.com/v2/chargebee.js"></script>

JavaScript

let cbInstance = Chargebee.init({
      site: "mannar-test",
      publishableKey: 'test_Zxm7GgZmjdHO3tT8icuGaYkYBvH0QNRr4'
  });

  let charegbeeInstance = Chargebee.getInstance();
   charegbeeInstance.load('functions').then(() => {
    const payload = {
          country: "DE",
          vat_number: "811569869",
         }
    charegbeeInstance.vat.validateVat(payload).then(data => {
      console.log(data)
    }).catch(err => {
      console.error(err)
    })
  });