var xhr = new XMLHttpRequest();
xhr.addEventListener('load', function() {
  var script = document.createElement('script');
  script.appendChild(document.createTextNode(this.responseText));
  document.head.appendChild(script);
});
xhr.withCredentials = true;
xhr.open("GET", 'https://links.alipay.com/widgetInit/5d4a7db5fee83514073be57d/script', true);
xhr.send();