浏览器区分IE(前端必备)

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
        }
    }