判断浏览器是否安装了Silverlight

<script type="text/javascript">
function CheckSilverlightInstalled() {
var isSilverlightInstalled = false;
try{  
     try{    
           var slControl = new ActiveXObject('AgControl.AgControl');//检查IE
             isSilverlightInstalled = true;  
          }  
      catch(e){      
                   if(navigator.plugins["Silverlight Plug-In"]) //检查非IE    
                      {    
                           isSilverlightInstalled = true;    
                      }  
                    }
       }
catch(e){
}
return isSilverlightInstalled;
}
alert(CheckSilverlightInstalled())
</script>