你可以使用navigator对象来检测user-navigator，你不需要jquery，下面的4个注释已经包括在内，所以这个代码片段可以正常工作

if (/MSIE (\d+\.\d+);/.test(navigator.userAgent) || navigator.userAgent.indexOf("Trident/") > -1 ){ 
 // Do stuff with Internet-Exploders ... :)
}

http://www.javascriptkit.com/javatutors/navigator.shtml

JavaScript检测ie或Edge版本的功能

function ieVersion(uaString) {
  uaString = uaString || navigator.userAgent;
  var match = /\b(MSIE |Trident.*?rv:|Edge\/)(\d+)/.exec(uaString);
  if (match) return parseInt(match[2])
}

对于任何版本的Internet Explorer都返回true:

function isIE(userAgent) {
  userAgent = userAgent || navigator.userAgent;
  return userAgent.indexOf("MSIE ") > -1 || userAgent.indexOf("Trident/") > -1 || userAgent.indexOf("Edge/") > -1;
}

userAgent参数是可选的，默认为浏览器的用户代理。

方法1: 美元。浏览器在jQuery 1.3版中已弃用，并在1.9版中被移除

if ( $.browser.msie) {
  alert( "Hello! This is IE." );
}

方法2: 使用条件注释

<!--[if gte IE 8]>
<p>You're using a recent version of Internet Explorer.</p>
<![endif]-->

<!--[if lt IE 7]>
<p>Hm. You should upgrade your copy of Internet Explorer.</p>
<![endif]-->

<![if !IE]>
<p>You're not using Internet Explorer.</p>
<![endif]>

方法03:

 /**
 * Returns the version of Internet Explorer or a -1
 * (indicating the use of another browser).
 */
function getInternetExplorerVersion()
{
    var rv = -1; // Return value assumes failure.

    if (navigator.appName == 'Microsoft Internet Explorer')
    {
        var ua = navigator.userAgent;
        var re  = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
        if (re.exec(ua) != null)
            rv = parseFloat( RegExp.$1 );
    }

    return rv;
}

function checkVersion()
{
    var msg = "You're not using Internet Explorer.";
    var ver = getInternetExplorerVersion();

    if ( ver > -1 )
    {
        if ( ver >= 8.0 ) 
            msg = "You're using a recent copy of Internet Explorer."
        else
            msg = "You should upgrade your copy of Internet Explorer.";
    }

    alert( msg );
}

方法04: 使用JavaScript/手动检测

/*
     Internet Explorer sniffer code to add class to body tag for IE version.
     Can be removed if your using something like Modernizr.
 */
 var ie = (function ()
 {

     var undef,
     v = 3,
         div = document.createElement('div'),
         all = div.getElementsByTagName('i');

     while (
     div.innerHTML = '<!--[if gt IE ' + (++v) + ']><i></i>< ![endif]-->',
     all[0]);

     //append class to body for use with browser support
     if (v > 4)
     {
         $('body').addClass('ie' + v);
     }

 }());

参考链接

几年后，Edge浏览器现在使用Chromium作为渲染引擎。 遗憾的是，检查IE 11仍然是一件事。

这里有一个更直接的方法，因为古老版本的IE应该消失了。

if (window.document.documentMode) {
  // Do IE stuff
}

---

以下是我以前的答案(2014年):

在Edge中，用户代理字符串已更改。

/**
 * detect IEEdge
 * returns version of IE/Edge or false, if browser is not a Microsoft browser
 */
function detectIEEdge() {
    var ua = window.navigator.userAgent;

    var msie = ua.indexOf('MSIE ');
    if (msie > 0) {
        // IE 10 or older => return version number
        return parseInt(ua.substring(msie + 5, ua.indexOf('.', msie)), 10);
    }

    var trident = ua.indexOf('Trident/');
    if (trident > 0) {
        // IE 11 => return version number
        var rv = ua.indexOf('rv:');
        return parseInt(ua.substring(rv + 3, ua.indexOf('.', rv)), 10);
    }

    var edge = ua.indexOf('Edge/');
    if (edge > 0) {
       // Edge => return version number
       return parseInt(ua.substring(edge + 5, ua.indexOf('.', edge)), 10);
    }

    // other browser
    return false;
}

示例用法:

alert('IEEdge ' + detectIEEdge());

ie10默认字符串:

Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)

IE 11默认字符串:

Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko 

Edge 12的默认字符串:

Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36 Edge/12.0 

Edge 13的默认字符串(thx @DrCord):

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2486.0 Safari/537.36 Edge/13.10586 

Edge 14的默认字符串:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2486.0 Safari/537.36 Edge/14.14300 

Edge 15的默认字符串:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36 Edge/15.15063 

Edge 16的默认字符串:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36 Edge/16.16299 

Edge 17的默认字符串:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/17.17134 

Edge 18的默认字符串(内部预览):

Mozilla/5.0 (Windows NT 10.0; Win64; x64; ServiceUI 14) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/18.17730 

在CodePen进行测试:

http://codepen.io/gapcode/pen/vEJNZN

我知道这是一个老问题，但如果有人再次遇到这个问题，并且无法检测IE11，这里有一个适用于所有当前版本的IE的有效解决方案。

var isIE = false;
if (navigator.userAgent.indexOf('MSIE') !== -1 || navigator.appVersion.indexOf('Trident/') > 0) {
    isIE = true;   
}