<script type="text/javascript">

        var Sys = {};

        var ua = navigator.userAgent.toLowerCase();

        window.ActiveXObject ? Sys.ie = ua.match(/msie ([\d.]+)/)[1] :

        document.getBoxObjectFor ? Sys.firefox = ua.match(/firefox\/([\d.]+)/)[1] :

        window.MessageEvent && !document.getBoxObjectFor ? Sys.chrome = ua.match(/chrome\/([\d.]+)/)[1] :

        window.opera ? Sys.opera = ua.match(/opera.([\d.]+)/)[1] :

        window.openDatabase ? Sys.safari = ua.match(/version\/([\d.]+)/)[1] : 0;

       

        //以下进行测试

        if(Sys.ie) document.write('IE: '+Sys.ie);

        if(Sys.firefox) document.write('Firefox: '+Sys.firefox);

        if(Sys.chrome) document.write('Chrome: '+Sys.chrome);

        if(Sys.opera) document.write('Opera: '+Sys.opera);

        if(Sys.safari) document.write('Safari: '+Sys.safari);

    </script>

------解决方案--------------------

// 判断浏览器;  
function getOs()  
{  
   var OsObject = "";  
   if(navigator.userAgent.indexOf("MSIE")>0) {  
        return "MSIE";  
   }  
   if(isFirefox=navigator.userAgent.indexOf("Firefox")>0){  
        return "Firefox";  
   }  
   if(isSafari=navigator.userAgent.indexOf("Safari")>0) {  
        return "Safari";  
   }   
   if(isCamino=navigator.userAgent.indexOf("Camino")>0){  
        return "Camino";  
   }  
   if(isMozilla=navigator.userAgent.indexOf("Gecko/")>0){  
        return "Gecko";  
   }  
}