我推荐使用小型javascript库Bowser。它基于导航器。userAgent和相当好测试的所有浏览器，包括iphone, android等。

https://github.com/ded/bowser

你可以简单地说:

if (bowser.msie && bowser.version <= 6) {
  alert('Hello IE');
} else if (bowser.firefox){
  alert('Hello Foxy');
} else if (bowser.chrome){
  alert('Hello Chrome');
} else if (bowser.safari){
  alert('Hello Safari');
} else if(bowser.iphone || bowser.android){
  alert('Hello mobile');
}

您可以使用jQuery库来检测浏览器版本。

例子:

jQuery.browser.version

然而，这只有在你同时使用jQuery的其他函数时才有意义。对我来说，仅仅为了检测浏览器而添加整个库似乎有点小题大做。

更多信息: http://api.jquery.com/jQuery.browser/

(你需要向下滚动一点)

如果你想要一个返回浏览器和版本的函数，这里是对原始答案的改进:

navigator.browserInfo = 
(
    function()
    {
        var browser = '';
        var version = '';
        var idString = '';

        var ua = navigator.userAgent;
        var tem = [];
        var M = ua.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i);

        //IE will be identified as 'Trident' and a different version number. The name must be corrected to 'Internet Explorer' and the correct version identified.
        //ie correction
        if(/trident/i.test(M[1]))
        {
            tem = /\brv[ :]+(\d+.?\d*)/g.exec(ua) || [];
            browser = 'Internet Explorer';
            version = tem[1];
        }

        //firefox
        else if(/firefox/i.test(M[1]))
        {
            tem = /\brv[ :]+(\d+.?\d*)/g.exec(ua) || [];
            browser = 'Firefox';
            version = tem[1];
        }

        //safari
        else if(/safari/i.test(M[1]))
        {
            tem = ua.match(/\bVersion\/(\d+.?\d*\s*\w+)/);
            browser = 'Safari';
            version = tem[1];
        }

        //If 'Chrome' is found, it may be another browser. 
        else if(M[1] === 'Chrome')
        {
            //opera
            var temOpr = ua.match(/\b(OPR)\/(\d+.?\d*.?\d*.?\d*)/);
            //edge
            var temEdge = ua.match(/\b(Edge)\/(\d+.?\d*)/);
            //chrome
            var temChrome = ua.match(/\b(Chrome)\/(\d+.?\d*.?\d*.?\d*)/);

            //a genuine 'Chrome' reading will result from ONLY temChrome not being null.
            var genuineChrome = temOpr == null && temEdge == null && temChrome != null;

            if(temOpr != null)
            {
                browser = temOpr[1].replace('OPR', 'Opera');
                version = temOpr[2];
            }

            if(temEdge != null)
            {
                browser = temEdge[1];
                version = temEdge[2];
            }

            if(genuineChrome)
            {
                browser = temChrome[1];
                version = temChrome[2];
            }
        }
        //There will be some odd balls, so if you wish to support those browsers, add functionality to display those browsers as well.

        if(browser == '' || version == '')
        {
            idString = 'We couldn\'t find your browser, but you can still use the site';
        }
        else
        {
            idString = browser + ' version ' + version;
        }

        alert('Your browser is ' + idString);

        //store the type of browser locally
        if(typeof(Storage) !== "undefined")
        {
            //Store
            localStorage.setItem('browser', browser);
            localStorage.setItem('version', version);
        } 
        else
        {
            alert('local storage not available');
        }
    }
)();

这样，它还将结果存储在本地，因此不必每次都执行该检查。

var isOpera = !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 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 && !isOpera;              // Chrome 1+
var isIE = /*@cc_on!@*/false || !!document.documentMode;
// Edge 20+
var isEdge = !isIE && !!window.StyleMedia;
// Chrome 1+
var output = 'Detecting browsers by ducktyping:<hr>';
output += 'isFirefox: ' + isFirefox + '<br>';
output += 'isChrome: ' + isChrome + '<br>';
output += 'isSafari: ' + isSafari + '<br>';
output += 'isOpera: ' + isOpera + '<br>';
output += 'isIE: ' + isIE + '<br>';
output += 'isIE Edge: ' + isEdge + '<br>';
document.body.innerHTML = output;

 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?

我做了这个小函数，希望对大家有帮助。在这里你可以找到最新的版本 browserDetection

function detectBrowser(userAgent){
  var chrome  = /.*(Chrome\/).*(Safari\/).*/g;
  var firefox = /.*(Firefox\/).*/g;
  var safari  = /.*(Version\/).*(Safari\/).*/g;
  var opera   = /.*(Chrome\/).*(Safari\/).*(OPR\/).*/g

  if(opera.exec(userAgent))
    return "Opera"
  if(chrome.exec(userAgent))
    return "Chrome"
  if(safari.exec(userAgent))
    return "Safari"
  if(firefox.exec(userAgent))
    return "Firefox"
}