gets the ie version of the browser, else returns -1

ieversion.jquery.js

//usage: returns IE version else -1
function getInternetExplorerVersion()
    // Returns the version of Internet Explorer or a -1
    // (indicating the use of another browser).
    {
      rv = -1; // Return value assumes failure.
      if (navigator.appName == 'Microsoft Internet Explorer')
      {
        var ua = navigator.userAgent;
        var re  = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
        if (re.exec(ua) != null)
          rv = parseFloat( RegExp.$1 );
      }
        return rv;
    }