var acceptableVersions = {
    
"Firefox": 34, "Chrome": 39, "Microsoft Edge": 11, "Internet Explorer": 11, "Safari": 8
      };

      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: "OPR",
              identity: "Opera",
              versionSearch: "OPR"
          }, {
              string: navigator.userAgent,
              subString: "Vivaldi",
              identity: "Vivaldi"
          }, {
              string: navigator.userAgent,
              subString: "Chrome",
              identity: "Chrome"
          }, {
              string: navigator.userAgent,
              subString: "OmniWeb",
              versionSearch: "OmniWeb/",
              identity: "OmniWeb"
          }, {
              string: navigator.userAgent,
              subString: "CriOS",
              identity: "Chrome",
              versionSearch: "CriOS"
          }, {
              string: navigator.vendor,
              subString: "Apple",
              identity: "Safari",
              versionSearch: "Version"
          }, { // old Opera
              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: "Internet Explorer",
              versionSearch: "MSIE"
          }, {
              string: navigator.userAgent,
              subString: ".NET4",
              identity: "Microsoft Edge",
              versionSearch: "rv"
          }, {
              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.userAgent,
              subString: "Windows Phone",
              identity: "Windows Phone"
          }, {
              string: navigator.platform,
              subString: "Win",
              identity: "Windows"
          }, {
              string: navigator.platform,
              subString: "Mac",
              identity: "Mac"
          }, {
              string: navigator.userAgent,
              subString: "iPhone",
              identity: "iPhone/iPod"
          }, {
              string: navigator.userAgent,
              subString: "Android",
              identity: "Android"
          }, {
              string: navigator.platform,
              subString: "Linux",
              identity: "Linux"
          }, {
              string: navigator.platform,
              subString: "iPad",
              identity: "iPad"
          }]

      };
      BrowserDetect.init();
      
      function browserOk() {
        // check if the browser is ok
        return (acceptableVersions[BrowserDetect.browser] !== undefined && BrowserDetect.version >= acceptableVersions[BrowserDetect.browser]);
      }