如何检测浏览器是否安装了Shockwave及Quicktime视频插件

var myPlugin =navigator.plugins["Shockwave"];
if (myPlugin)
document.writeln("你已经安装了Shockwave!")
else
document.writeln("你尚未安装Shockwave!")
// -->
</script>
<script LANGUAGE="JavaScript">
<!--
var myPlugin =navigator.plugins["Quicktime"];
if (myPlugin)
document.writeln("你已经安装了Quicktime!")
else
document.writeln("你尚未安装Quicktime!")
// -->
</script>