遗憾的是，IE11的导航器中不再有MSIE。

Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; OfficeLiveConnector.1.5; OfficeLivePatch.1.3; .NET4.0C; BRI/2; BOIE9;ENUS; rv:11.0) like Gecko

至于为什么你想知道你在使用哪个浏览器，这是因为每个浏览器都有自己的一组错误，你最终实现了浏览器和版本特定的解决方案，或者告诉用户使用不同的浏览器!

下面是我如何为Internet Explorer做自定义CSS:

在我的JavaScript文件:

function isIE () {
      var myNav = navigator.userAgent.toLowerCase();
      return (myNav.indexOf('msie') != -1) ? parseInt(myNav.split('msie')[1]) : false;
}

jQuery(document).ready(function(){
    if(var_isIE){
            if(var_isIE == 10){
                jQuery("html").addClass("ie10");
            }
            if(var_isIE == 8){
                jQuery("html").addClass("ie8");
                // you can also call here some function to disable things that 
                //are not supported in IE, or override browser default styles.
            }
        }
    });

然后在我的CSS文件中，定义每个不同的样式:

.ie10 .some-class span{
    .......
}
.ie8 .some-class span{
    .......
}

遗憾的是，IE11的导航器中不再有MSIE。

Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; OfficeLiveConnector.1.5; OfficeLivePatch.1.3; .NET4.0C; BRI/2; BOIE9;ENUS; rv:11.0) like Gecko

至于为什么你想知道你在使用哪个浏览器，这是因为每个浏览器都有自己的一组错误，你最终实现了浏览器和版本特定的解决方案，或者告诉用户使用不同的浏览器!

 var isOpera = !!window.opera || navigator.userAgent.indexOf('Opera') >= 0;
        // Opera 8.0+ (UA detection to detect Blink/v8-powered Opera)
        var isFirefox = typeof InstallTrigger !== 'undefined';   // Firefox 1.0+
        var isSafari = Object.prototype.toString.call(window.HTMLElement).indexOf('Constructor') > 0;
        // At least Safari 3+: "[object HTMLElementConstructor]"
        var isChrome = !!window.chrome;                          // Chrome 1+
        var isIE = /*@cc_on!@*/false; 

你可以阅读更多 如何检测Safari, Chrome, IE, Firefox和Opera浏览器?

这是我写来获取客户信息的

var ua = navigator.userAgent.toLowerCase();
var check = function(r) {
    return r.test(ua);
};
var DOC = document;
var isStrict = DOC.compatMode == "CSS1Compat";
var isOpera = check(/opera/);
var isChrome = check(/chrome/);
var isWebKit = check(/webkit/);
var isSafari = !isChrome && check(/safari/);
var isSafari2 = isSafari && check(/applewebkit\/4/); // unique to
// Safari 2
var isSafari3 = isSafari && check(/version\/3/);
var isSafari4 = isSafari && check(/version\/4/);
var isIE = !isOpera && check(/msie/);
var isIE7 = isIE && check(/msie 7/);
var isIE8 = isIE && check(/msie 8/);
var isIE6 = isIE && !isIE7 && !isIE8;
var isGecko = !isWebKit && check(/gecko/);
var isGecko2 = isGecko && check(/rv:1\.8/);
var isGecko3 = isGecko && check(/rv:1\.9/);
var isBorderBox = isIE && !isStrict;
var isWindows = check(/windows|win32/);
var isMac = check(/macintosh|mac os x/);
var isAir = check(/adobeair/);
var isLinux = check(/linux/);
var isSecure = /^https/i.test(window.location.protocol);
var isIE7InIE8 = isIE7 && DOC.documentMode == 7;

var jsType = '', browserType = '', browserVersion = '', osName = '';
var ua = navigator.userAgent.toLowerCase();
var check = function(r) {
    return r.test(ua);
};

if(isWindows){
    osName = 'Windows';

    if(check(/windows nt/)){
        var start = ua.indexOf('windows nt');
        var end = ua.indexOf(';', start);
        osName = ua.substring(start, end);
    }
} else {
    osName = isMac ? 'Mac' : isLinux ? 'Linux' : 'Other';
} 

if(isIE){
    browserType = 'IE';
    jsType = 'IE';

    var versionStart = ua.indexOf('msie') + 5;
    var versionEnd = ua.indexOf(';', versionStart);
    browserVersion = ua.substring(versionStart, versionEnd);

    jsType = isIE6 ? 'IE6' : isIE7 ? 'IE7' : isIE8 ? 'IE8' : 'IE';
} else if (isGecko){
    var isFF =  check(/firefox/);
    browserType = isFF ? 'Firefox' : 'Others';;
    jsType = isGecko2 ? 'Gecko2' : isGecko3 ? 'Gecko3' : 'Gecko';

    if(isFF){
        var versionStart = ua.indexOf('firefox') + 8;
        var versionEnd = ua.indexOf(' ', versionStart);
        if(versionEnd == -1){
            versionEnd = ua.length;
        }
        browserVersion = ua.substring(versionStart, versionEnd);
    }
} else if(isChrome){
    browserType = 'Chrome';
    jsType = isWebKit ? 'Web Kit' : 'Other';

    var versionStart = ua.indexOf('chrome') + 7;
    var versionEnd = ua.indexOf(' ', versionStart);
    browserVersion = ua.substring(versionStart, versionEnd);
}else{
    browserType = isOpera ? 'Opera' : isSafari ? 'Safari' : '';
}

所有关于web浏览器的信息都包含在navigator对象中。名字和版本都在那里。

var appname = window.navigator.appName;

来源:javascript浏览器检测