js判断是否安装flash

<script type="text/javascript">
(function () {
var noFlash = "你的浏览器没有安装Flash，会影响视频查看和上传图片...";
var isIE = !-[1, ];
if (isIE) {
try {
var swf1 = new ActiveXObject('ShockwaveFlash.ShockwaveFlash');
//alert('安装了Flash');
}
catch (e) {
alert(noFlash);
}
}
else {
try {
var swf2 = navigator.plugins['Shockwave Flash'];
if (swf2 == undefined) {
alert(noFlash);
}
else {
//alert('安装了Flash');
}
}
catch (e) {
alert(noFlash);
}
}
})();
</script>