js区分浏览器

function myBrowser() {
    var userAgent = navigator.userAgent; //取得浏览器的userAgent字符串
    var isOpera = userAgent.indexOf("Opera") > -1; //判断是否Opera浏览器
    var isIE = userAgent.indexOf("compatible") > -1
            && userAgent.indexOf("MSIE") > -1 && !isOpera; //判断是否IE浏览器
    var isEdge = userAgent.indexOf("Edge") > -1; //判断是否IE的Edge浏览器
    var isFF = userAgent.indexOf("Firefox") > -1; //判断是否Firefox浏览器
    var isSafari = userAgent.indexOf("Safari") > -1
            && userAgent.indexOf("Chrome") == -1; //判断是否Safari浏览器
    var isChrome = userAgent.indexOf("Chrome") > -1
            && userAgent.indexOf("Safari") > -1; //判断Chrome浏览器

    if (isIE) {
        var reIE = new RegExp("MSIE (\d+\.\d+);");
        reIE.test(userAgent);
        var fIEVersion = parseFloat(RegExp["$1"]);
        if (fIEVersion == 7) {
            return "IE7";
        } else if (fIEVersion == 8) {
            return "IE8";
        } else if (fIEVersion == 9) {
            return "IE9";
        } else if (fIEVersion == 10) {
            return "IE10";
        } else if (fIEVersion == 11) {
            return "IE11";
        } else {
            return "0";
        }//IE版本过低
        return "IE";
    }
    if (isOpera) {
        return "Opera";
    }
    if (isEdge) {
        return "Edge";
    }
    if (isFF) {
        return "FF";
    }
    if (isSafari) {
        return "Safari";
    }
    if (isChrome) {
        return "Chrome";
    }
    
}