if ( !jQuery.browser ) {
      var uaMatch = function( ua ) {
        ua = ua.toLowerCase();

        var match = /(chrome)[ \/]([\w.]+)/.exec( ua ) ||
          /(webkit)[ \/]([\w.]+)/.exec( ua ) ||
          /(opera)(?:.*version|)[ \/]([\w.]+)/.exec( ua ) ||
          /(msie) ([\w.]+)/.exec( ua ) ||
          ua.indexOf("compatible") < 0 && /(mozilla)(?:.*? rv:([\w.]+)|)/.exec( ua ) ||
          [];

        return {
          browser: match[ 1 ] || "",
          version: match[ 2 ] || "0"
        };
      };

      matched = uaMatch( navigator.userAgent );
      browser = {};

      if ( matched.browser ) {
        browser[ matched.browser ] = true;
        browser.version = matched.version;
      }

      // Chrome is Webkit, but Webkit is also Safari.
      if ( browser.chrome ) {
        browser.webkit = true;
      } else if ( browser.webkit ) {
        browser.safari = true;
      }

      jQuery.browser = browser;
    }