检测新窗口"myWindow" 是否已被关闭 - 在线编辑器

          <!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>蜜蜂教程(mifengjc.com)</title>
  <script>
    var myWindow;

    function openWin() {
      myWindow = window.open("", "", "width=400,height=200");
    }

    function closeWin() {
      if (myWindow) {
        myWindow.close();
      }
    }

    function checkWin() {
      if (!myWindow) {
        document.getElementById("msg").innerHTML = "我的窗口没有被打开!";
      } else {
        if (myWindow.closed) {
          document.getElementById("msg").innerHTML = "我的窗口被关闭!";
        } else {
          document.getElementById("msg").innerHTML = "我的窗口没有被关闭!";
        }
      }
    }
  </script>
</head>
<body>

  <input type="button" value="打开我的窗口" onclick="openWin()" />
  <input type="button" value="关闭我的窗口" onclick="closeWin()" />
  <br><br>
  <input type="button" value="我的窗口被关闭了吗?" onclick="checkWin()" />
  <br><br>
  <div id="msg"></div>

</body>
</html>
        