Question

我有一些javascript可以获取浏览器的浏览器名称和版本号。一切正常;我正确地得到了正确的名称和版本，除非它是一个特定的网站。在该特定站点上，而不是我的IE9显示版本9，显示版本8。如果我再次在其他浏览器中测试，则名称和版本是正确的。问题只在IE中。它不仅仅是IE9;该特定网站上的IE8显示版本7.我还刚刚使用javascript创建了一个单独的HTML页面，我得到了正确的版本号。代码如下：

<html>
    <head>

        <script type="text/javascript">
    var BrowserDetect = {
            init: function () {
                this.browser = this.searchString(this.dataBrowser) || "An unknown browser";
                this.version = this.searchVersion(navigator.userAgent)
                    || this.searchVersion(navigator.appVersion)
                    || "an unknown version";
                this.OS = this.searchString(this.dataOS) || "an unknown OS";
            },
            searchString: function (data) {
                for (var i=0;i<data.length;i++) {
                    var dataString = data[i].string;
                    var dataProp = data[i].prop;
                    this.versionSearchString = data[i].versionSearch || data[i].identity;
                    if (dataString) {
                        if (dataString.indexOf(data[i].subString) != -1)
                            return data[i].identity;
                    }
                    else if (dataProp)
                        return data[i].identity;
                }
            },
            searchVersion: function (dataString) {
                alert("this.versionSearchString: " + this.versionSearchString);
                alert("useragent: " + dataString);
                var index = dataString.indexOf(this.versionSearchString);
                if (index == -1) return;
                return parseFloat(dataString.substring(index+this.versionSearchString.length+1));
            },
            dataBrowser: [
                {
                    string: navigator.userAgent,
                    subString: "Chrome",
                    identity: "Chrome"
                },
                {   string: navigator.userAgent,
                    subString: "OmniWeb",
                    versionSearch: "OmniWeb/",
                    identity: "OmniWeb"
                },
                {
                    string: navigator.vendor,
                    subString: "Apple",
                    identity: "Safari",
                    versionSearch: "Version"
                },
                {
                    prop: window.opera,
                    identity: "Opera"
                },
                {
                    string: navigator.vendor,
                    subString: "iCab",
                    identity: "iCab"
                },
                {
                    string: navigator.vendor,
                    subString: "KDE",
                    identity: "Konqueror"
                },
                {
                    string: navigator.userAgent,
                    subString: "Firefox",
                    identity: "Firefox"
                },
                {
                    string: navigator.vendor,
                    subString: "Camino",
                    identity: "Camino"
                },
                {       // for newer Netscapes (6+)
                    string: navigator.userAgent,
                    subString: "Netscape",
                    identity: "Netscape"
                },
                {
                    string: navigator.userAgent,
                    subString: "MSIE",
                    identity: "Explorer",
                    versionSearch: "MSIE"
                },
                {
                    string: navigator.userAgent,
                    subString: "Gecko",
                    identity: "Mozilla",
                    versionSearch: "rv"
                },
                {       // for older Netscapes (4-)
                    string: navigator.userAgent,
                    subString: "Mozilla",
                    identity: "Netscape",
                    versionSearch: "Mozilla"
                }
            ],
            dataOS : [
                {
                    string: navigator.platform,
                    subString: "Win",
                    identity: "Windows"
                },
                {
                    string: navigator.platform,
                    subString: "Mac",
                    identity: "Mac"
                },
                {
                       string: navigator.userAgent,
                       subString: "iPhone",
                       identity: "iPhone/iPod"
                },
                {
                    string: navigator.platform,
                    subString: "Linux",
                    identity: "Linux"
                }
            ]

        };
        BrowserDetect.init();
    </script>
        <script>
        function browserCheck() {
            var invalid = false;
            var browser = BrowserDetect.browser;
            var version = BrowserDetect.version;

            alert("Browser: " + browser + ", Version: " + version);



    if (browser == 'Firefox'){
            if (parseFloat(version) < parseFloat('3.0')){
                invalid = true;
            }
        } else if (browser == 'Explorer'){
            if (parseFloat(version) < parseFloat('8.0')){
                invalid = true;
            }
        } else {
            invalid = true;
        }

        if (invalid){
            //some action
        }
    }
    </script>
</head>
<body onload="browserCheck()">

</body>
</html>

为什么特定网站会显示错误的浏览器版本？

Answer 1

IE9 http://blogs.msdn.com/b/ie/archive/2010/03/23/introducing-ie9-s-user-agent-string.aspx和IE8 http://blogs.msdn.com/b/ie/archive/2009/01/09/the-internet-explorer-8-user-agent-string-updated-edition.aspx具有兼容User Agent（UA）字符串的兼容模式。因此，您可以使用IE9，但可以在 Compatilbility模式中查看网站，这可以将UA更改为IE8，这可能就是您所看到的。

如果你不介意完整库的额外开销，jQuery有内置的browser detection，我相信如果IE欺骗UA，它仍会遇到同样的问题。修改实际上，确实有一种解决方法 - 请参阅Detect IE8 Compatibility Mode，但同样可能需要大量的开销进行浏览器检测。

总的来说（和其他人一样）UA嗅探是不可靠的，因为它可以很容易被欺骗。

Answer 2

杰森说。您似乎认为浏览器检测是可靠的;实际上，您只是在查看供应商决定使用的任何字符串。微软因其用户代理字符串而臭名昭着;注意他们在过去的20年里是如何写出“Mozilla”的。

MSIE版本不同

2 个答案: