This approach to detecting IE combines the strengths and avoids the weaknesses of jKey's answer using conditional comments and Owen's answer using user agents.
Owen's approach can fail on IE 5 & 6 (reporting 7) and is susceptible to UA spoofing, but it can detect IE versions >= 10 (now also including 12, which postdates Owen's answer).
// ----------------------------------------------------------
// A short snippet for detecting versions of IE
// ----------------------------------------------------------
// If you're not in IE (or IE version is less than 5) then:
// ie === undefined
// Thus, to detect IE:
// if (ie) {}
// And to detect the version:
// ie === 6 // IE6
// ie > 7 // IE8, IE9 ...
// ----------------------------------------------------------
var ie = (function(){
var v = 3,
div = document.createElement('div'),
all = div.getElementsByTagName('i');
while (
div.innerHTML = '<!--[if gt IE ' + (++v) + ']><i></i><![endif]-->',
all[0]
);
if (v <= 4) { // Check for IE>9 using user agent
var match = navigator.userAgent.match(/(?:MSIE |Trident\/.*; rv:|Edge\/)(\d+)/);
v = match ? parseInt(match[1]) : undefined;
}
return v;
}());
This can be used to set useful classes to your document containing the IE version:
if (ie) {
document.documentElement.className += ' ie' + ie;
if (ie < 9)
document.documentElement.className += ' ieLT9';
}
Note that it detects the compatibility mode being used, if IE is in compatability mode. Also note that IE version is mostly useful for older versions (<10); higher versions are more standards-compliant and it's probably better to instead check for features using something like modernizr.js.