code: function getIEVersion () {
      var ieMatch = /MSIE (\d+)/.exec( navigator.userAgent ) || /Trident\/.+? rv:(\d+)/.exec( navigator.userAgent );
      return ( ieMatch && ieMatch.length ) ? parseFloat( ieMatch[1] ) : 0;
  }
docs: Detects the IE version. Returns the major version number, or 0 if the browser is not IE.
  
  Simple solution, solely based on UA sniffing. In a better implementation, conditional comments would be used to
  detect IE6 to IE9 - see https://gist.github.com/cowboy/542301 for an example. UA sniffing would only serve as a
  fallback to detect IE > 9. There are also other solutions to infer the version of IE > 9. For inspiration, see
  http://stackoverflow.com/q/17907445/508355.