区分IE版本的js代码

 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<11浏览器
         var isEdge = userAgent.indexOf("Edge") > -1 && !isIE; //判断是否IE的Edge浏览器
         var isIE11 = userAgent.indexOf('Trident') > -1 && userAgent.indexOf("rv:11.0") > -1;
         if(isIE) {
             var reIE = new RegExp("MSIE (\\d+\\.\\d+);");
             reIE.test(userAgent);
             var fIEVersion = parseFloat(RegExp["$1"]);
             if(fIEVersion == 7) {
                 return 7;
             } else if(fIEVersion == 8) {
                 return 8;
             } else if(fIEVersion == 9) {
                 return 9;
             } else if(fIEVersion == 10) {
                 return 10;
             } else {
                 return 6;//IE版本<=7
             }
         } else if(isEdge) {
             return 'edge';//edge
         } else if(isIE11) {
             return 11; //IE11
         }else{
             return -1;//不是ie浏览器
         }
     }