浏览器的版本号

 function isBroswer () {//检测浏览器内核--返回的是两个key，name：浏览器内核的名称---version：浏览器的版本号
            var _broswer = {};
            var sUserAgent = navigator.userAgent;
            var isOpera = sUserAgent.indexOf("Opera") > -1;
            if (isOpera) {
                //首先检测Opera是否进行了伪装
                if (navigator.appName == 'Opera') {
                    //如果没有进行伪装，则直接后去版本号
                    _broswer.version = parseFloat(navigator.appVersion);
                } else {
                    var reOperaVersion = new RegExp("Opera (\\d+.\\d+)");
                    //使用正则表达式的test方法测试并将版本号保存在RegExp.$1中
                    reOperaVersion.test(sUserAgent);
                    _broswer.version = parseFloat(RegExp['$1']);
                }
                _broswer.opera = true;
                _broswer.name = 'opera';
            }
            var isChrome = sUserAgent.indexOf("Chrome") > -1;
            if (isChrome) {
                var reChorme = new RegExp("Chrome/(\\d+\\.\\d+(?:\\.\\d+\\.\\d+))?");
                reChorme.test(sUserAgent);
                _broswer.version = parseFloat(RegExp['$1']);
                _broswer.chrome = true;
                _broswer.name = 'chrome';
            }
            //排除Chrome信息，因为在Chrome的user-agent字符串中会出现Konqueror/Safari的关键字
            var isKHTML = (sUserAgent.indexOf("KHTML") > -1
                || sUserAgent.indexOf("Konqueror") > -1 || sUserAgent
                    .indexOf("AppleWebKit") > -1)
                && !isChrome;
            if (isKHTML) {//判断是否基于KHTML，如果时的话在继续判断属于何种KHTML浏览器
                var isSafari = sUserAgent.indexOf("AppleWebKit") > -1;
                var isKonq = sUserAgent.indexOf("Konqueror") > -1;
                if (isSafari) {
                    var reAppleWebKit = new RegExp("Version/(\\d+(?:\\.\\d*)?)");
                    reAppleWebKit.test(sUserAgent);
                    var fAppleWebKitVersion = parseFloat(RegExp["$1"]);
                    _broswer.version = parseFloat(RegExp['$1']);
                    _broswer.safari = true;
                    _broswer.name = 'safari';
                } else if (isKonq) {
                    var reKong = new RegExp(
                        "Konqueror/(\\d+(?:\\.\\d+(?\\.\\d)?)?)");
                    reKong.test(sUserAgent);
                    _broswer.version = parseFloat(RegExp['$1']);
                    _broswer.konqueror = true;
                    _broswer.name = 'konqueror';
                }
            }
            // !isOpera 避免是由Opera伪装成的IE
            var isIE = sUserAgent.indexOf("compatible") > -1
                && sUserAgent.indexOf("MSIE") > -1 && !isOpera;
            if (isIE) {
                var reIE = new RegExp("MSIE (\\d+\\.\\d+);");
                reIE.test(sUserAgent);
                _broswer.version = parseFloat(RegExp['$1']);
                _broswer.msie = true;
                _broswer.name = 'msie';
            }
            // 排除Chrome 及 Konqueror/Safari 的伪装
            var isMoz = sUserAgent.indexOf("Gecko") > -1 && !isChrome && !isKHTML;
            if (isMoz) {
                var reMoz = new RegExp("rv:(\\d+\\.\\d+(?:\\.\\d+)?)");
                reMoz.test(sUserAgent);
                _broswer.version = parseFloat(RegExp['$1']);
                _broswer.mozilla = true;
                _broswer.name = 'mozilla';
            }
            return _broswer;
        }
// 调用
        /**返回的是两个key，name：浏览器内核的名称---version：浏览器的版本号*/

 简版

 var theUA = window.navigator.userAgent.toLowerCase();
    if ((theUA.match(/msie\s\d+/) && theUA.match(/msie\s\d+/)[0]) || (theUA.match(/trident\s?\d+/) && theUA.match(/trident\s?\d+/)[0])) {
        var ieVersion = theUA.match(/msie\s\d+/)[0].match(/\d+/)[0] || theUA.match(/trident\s?\d+/)[0];
        if (ieVersion < 9) {
            var str = "你的浏览器版本太低了,请升级您的浏览器";
            var str2 = "<h2 style='font-weight:900;padding:10px 0;'>推荐使用：<a href='https://www.baidu.com/s?ie=UTF-8&wd=%E8%B0%B7%E6%AD%8C%E6%B5%8F%E8%A7%88%E5%99%A8' target='_blank' style='color:#ffffff;'>谷歌</a>,"
                + "<a href='https://www.baidu.com/s?ie=UTF-8&wd=%E7%81%AB%E7%8B%90%E6%B5%8F%E8%A7%88%E5%99%A8' target='_blank' style='color:#ffffff;'>火狐</a>,"
                + "或其他双核极速模式</h2>";
            document.writeln("<pre style='font-size:25px;text-align:center;color:#fff;background-color:#0cc; height:100%;border:0;position:fixed;top:0;left:0;width:100%;z-index:1234'>" +
                "<h2 style='padding-top:200px;margin:0'><strong>" + str + "<br/></strong></h2><h2>" +
                str2 + "</h2><h2 style='margin:0'><strong>如果您的使用的是360、搜狗、QQ等双核浏览器，请在最顶部切换到极速模式访问<br/></strong></h2>" +
                "<img src='../images/iechange.png' style='width:315px;height:200px;margin-top:10px;'></pre>");
            document.execCommand("Stop");
        }
    }