判断IE版本

function IEVersion()  
    {  
      var userAgent = navigator.userAgent; //取得浏览器的userAgent字符串  
      var isIE = userAgent.indexOf("compatible") > -1 && userAgent.indexOf("MSIE") > -1 ; //判断是否IE浏览器  
var isEdge = userAgent.indexOf("Windows NT 6.1; Trident/7.0;") > -1 && !isIE; //判断是否IE的Edge浏览器  
if(isIE)  
{  
 var reIE = new RegExp("MSIE (\\d+\\.\\d+);");  
 reIE.test(userAgent);  
 var fIEVersion = parseFloat(RegExp["$1"]);  
 if(fIEVersion == 7)  
   { alert( "IE7");}  
 else if(fIEVersion == 8)  
   { alert( "IE8");}  
 else if(fIEVersion == 9)  
   { alert( "IE9");}  
 else if(fIEVersion == 10)  
   { alert( "IE10");}  
 else if(fIEVersion == 11)  
   { alert( "IE11");}  
 else  
           { alert( "0")}//IE版本过低  
       }  
       else if(isEdge)  
       {  
        alert( "Edge");  
      }  
      else  
      {  
          alert( "-1");//非IE  
        }  
      }