To use captcha.eu with the npm hosted package use one of the following snippets.
npm install --save captcha-eu-sdkconst CaptchaEU = require('captcha-eu-sdk');
const KROT = CaptchaEU.KROT;import { KROT } from 'captcha-eu-sdk';KROT.init();For further details on how to use the JS sdk proceed here