IE和FF判断浏览器是否安装了flash插件

IE:

<script type="text/javascript"> 
  var swf=new ActiveXObject(\'ShockwaveFlash.ShockwaveFlash\');       
  (swf)? alert(\'你已经安装了插件\') : alert(\'你没有安装插件\');  
</script>  

FF:

<script type="text/javascript">
   var flag = false;
    for (i = 0; i < navigator.plugins.length; i++) {
        if (navigator.plugins[i].name == "Shockwave Flash")
            flag = true;
        break;
    }
    flag ? alert("你已经安装了插件") : alert("你没有安装插件");
</script>