request.js

const performARequest = () => {
  const httpRequest = new XMLHttpRequest();
  httpRequest.onreadystatechange = () => {
      if (httpRequest.readyState === 4 && httpRequest.status === 200) {
          console.log('Request successful!');
      }
  };

  httpRequest.open('GET', window.ENVIRONMENT.backendUrl + '/users/john');
  httpRequest.send();
};
performARequest();