Get Internet Explorer version; or return undefined if it is NOT internet explorer. Modded from james.padolsey.com/javascript/detect-ie-in-js-using-conditional-comments/ Unfortunately IE10 doesn't accept HTML conditional statements, so we have to use a JS conditional statement.

IE_detection.js

var ie = (function(){
 
    var undef,
        v = 3,
        div = document.createElement('div'),
        all = div.getElementsByTagName('i');
 
    do {
        div.innerHTML = '<!--[if gt IE ' + (++v) + ']><i></i><![endif]-->'; 
    } while(all[0]);
    /*@cc_on;if(v<5)v=10;@*/
    return v > 4 ? v : undef ;
 
}());

E.g.

    if(ie < 9){
        // Do something if is IE 8 or IE 7 or IE 6
    }