JAVASCRIPT Detect browser and set class to html tag

gistfile1.js

var BrowserDetect =
{
    init: function ()
    {
        this.browser = this.searchString(this.dataBrowser) || "Other";
        this.version = this.searchVersion(navigator.userAgent) ||       this.searchVersion(navigator.appVersion) || "Unknown";
    },

    searchString: function (data)
    {
        for (var i=0 ; i < data.length ; i++)
        {
            var dataString = data[i].string;
            this.versionSearchString = data[i].subString;

            if (dataString.indexOf(data[i].subString) != -1)
            {
                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: "MSIE",    identity: "Explorer" },
        { string: navigator.userAgent, subString: "Firefox", identity: "Firefox" },
        { string: navigator.userAgent, subString: "Safari",  identity: "Safari" },
        { string: navigator.userAgent, subString: "Opera",   identity: "Opera" }
    ]

};
BrowserDetect.init();
document.getElementsByTagName("html")[0].className = BrowserDetect.browser;