js判断浏览器版本(IE,FF,Chrome,Opear,Safari)

1. 五大浏览器判断

<script type="text/javascript">        
    var Sys = {};  
        var ua = navigator.userAgent.toLowerCase();  
        var s;  
        (s = ua.match(/msie ([\d.]+)/))? Sys.ie = s[1]:  
        (s = ua.match(/firefox\/([\d.]+)/))? Sys.firefox= s[1]:  
        (s = ua.match(/chrome\/([\d.]+)/))? Sys.chrome= s[1]:  
        (s = ua.match(/opera.([\d.]+)/))? Sys.opera= s[1]:  
        (s = ua.match(/version\/([\d.]+).*safari/))? Sys.safari= s[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>

2.IE浏览器版本

<!--[if IE]>    
<script type="text/javascript">    
alert("ie")    
</script>    
<![endif]-->    
<!--[if IE 6]>    
<script type="text/javascript">    
alert("ie6")    
</script>    
<![endif]-->    
<!--[if IE 7]>    
<script type="text/javascript">    
alert("ie7")    
</script>    
<![endif]-->