Javascript代码在除Internet Explorer之外的任何地方都可以使用

我编写这段JS代码是为了知道用户是用哪个浏览器打开文件的。 代码在任何地方都可以正常工作，但IE不行。 尝试将代码复制到html文件中，然后用google chrome打开它，它可以工作，但当你用IE打开它时，它不能工作。 代码如下：

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我想知道我的代码是否有问题，或者IE是否有bug。

为什么不使用现有的库来提供这些信息？还有更多，比如jquery？因为我想学习如何编写我想要的代码，而不是从Libraries获得它。在IE9中我也可以使用IE9中的IE7/8兼容模式

 <script><!--
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) {
    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",
        versionSearch: "Version"
    },
    {
        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 type="text/javascript">
<!--
document.write('<p class="accent">You\'re using ' + BrowserDetect.browser + ' ' +         
BrowserDetect.version + ' on ' + BrowserDetect.OS + '!</p>');
// -->
</script>