浏览器是否在线 - 在线编辑器

          <!DOCTYPE html>
<html>
<body>

  <p id="demo">Click the button to see if the browser is online.</p>

  <button onclick="myFunction()">Try it</button>

  <script>
    function myFunction() {
      var x = navigator.onLine;
      document.getElementById("demo").innerHTML = x;
    }
  </script>

</body>
</html>
        