检测页面是否允许使用Flash

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
<script>
    if (window.ActiveXObject) {
        var flag = new ActiveXObject('ShockwaveFlash.ShockwaveFlash');
        if(!flag){
            alert('请将您的浏览器设置中内容设置Flash项更改为允许！');
        }
    } else {
        var flag = navigator.plugins['Shockwave Flash'];
        if(!flag){
             alert('请将您的浏览器设置中内容设置Flash项更改为允许！');
        }
    }
</script>
</body>
</html>