722_ajax_取消请求

<script>
      var btns = document.querySelectorAll("button");
      let x;
      btns[0].onclick = function () {
        x = new XMLHttpRequest();
        x.open("GET", "http://127.0.0.1:8000/delay");
        x.send();
      };
      btns[1].onclick = function () {
        x.abort();
      };
    </script>