detect-ie.js

/**
 * modified from http://gist.github.com/527683
 * only improve slightly to get small
 */
var ie = function(v, p, needle, undef) {

    needle = p.getElementsByTagName('br');

    while(
        p.innerHTML = '<!--[if gt IE ' + (++v) + ']><br><![endif]-->',
        needle[0]
    );

    return v > 4 ? v : undef;

}(3, document.createElement('p'));

(you'll need to test p.getElementsByTagName('br')[0] in the while loop)

@cowboy: needle is live nodelist, don't need to re get in loop

How did I not know that? That's really interesting, thanks!