JS判断是否为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
            }
        }