detect.js

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();