如何通过id获取span元素？

Question

实际上，我创建了一个带有关闭图标的弹出窗口，并且我尝试使用span方法关闭弹出窗口。我想通过元素ID获取跨度元素值。

       <script>

  // Get the modal

  var modal = document.getElementById('myModal');

  // Get the button that opens the modal

  var btn = document.getElementById("myBtn");

  // Get the <span> element that closes the modal

  var span = document.getElementsByClassName("close")[1];

  // When the user clicks the button, open the modal

  btn.onclick = function() {

    modal.style.display = "block";

  }

  // When the user clicks on <span> (x), close the modal

  span.onclick = function() {

    modal.style.display = "none";

  }

  // When the user clicks anywhere outside of the modal, close it

  window.onclick = function(event) {

    if (event.target == modal) {

      modal.style.display = "none";

    }

  }

  </script>