A nice way to detect IE version

ie_detect.js

var ie = (function(){
    var undef, v = 3, div = document.createElement('div');
    while (
        div.innerHTML = '<!--[if gt IE '+(++v)+']><i></i><![endif]-->',
        div.getElementsByTagName('i')[0]
    );
    return v > 4 ? v : undef;
}());

var msie = typeof ie !== "undefined" ? true : false;