js判断是否是ie浏览器

        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            }
        }