下面的例子可提示当鼠标按键被点击时 "SHIFT" 键是否被按住 - 在线编辑器

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>蜜蜂教程(mifengjc.com)</title>
  <script>
    function isKeyPressed(event) {
      if (event.shiftKey == 1) {
        alert(" shift 键被按下!");
      } else {
        alert(" shift 键没被按下!");
      }
    }
  </script>
</head>
<body onmousedown="isKeyPressed(event)">

  <p>点击该段落，弹窗会提示是否按下 shift 键。</p>

</body>
</html>
​x
 
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>蜜蜂教程(mifengjc.com)</title>
  <script>
    function isKeyPressed(event) {
      if (event.shiftKey == 1) {
        alert(" shift 键被按下!");
      } else {
        alert(" shift 键没被按下!");
      }
    }
  </script>
</head>
<body onmousedown="isKeyPressed(event)">
​
  <p>点击该段落，弹窗会提示是否按下 shift 键。</p>
​
</body>
</html>