gistfile1.js

// ----------------------------------------------------------
// A short snippet for detecting versions of IE in JavaScript
// without resorting to user-agent sniffing
// ----------------------------------------------------------

// if (ie) { alert('IE ' + ie); } // else ie version is not a number;
// if(!ie) { alert ('IE is Kryptonite.'); }

var ie = (function(){
  var div = document.createElement('div');
  for (v=6;v<=9;v++)
    div.innerHTML += '<!--[if IE ' + v + ']>' + v + '<![endif]-->'
  return parseInt(div.innerHTML);
}());

if(!ie) { alert ('IE is Kryptonite.'); }

if(!ie) { alert ('IE is Kryptonite.'); }