spec/helpers/dom-utils.js
function getIEVersion () {
    var ieMatch = /MSIE (\d+)/.exec( navigator.userAgent ) || /Trident\/.+? rv:(\d+)/.exec( navigator.userAgent );
    return ( ieMatch && ieMatch.length ) ? parseFloat( ieMatch[1] ) : 0;
}
function getIEVersion () {
    var ieMatch = /MSIE (\d+)/.exec( navigator.userAgent ) || /Trident\/.+? rv:(\d+)/.exec( navigator.userAgent );
    return ( ieMatch && ieMatch.length ) ? parseFloat( ieMatch[1] ) : 0;
}
function getIEVersion ( ) { var ieMatch = / MSIE (\d+) / . exec ( navigator . userAgent ) || / Trident\/.+? rv:(\d+) / . exec ( navigator . userAgent ) ; return ( ieMatch && ieMatch . length ) ? parseFloat ( ieMatch [ 1 ] ) : 0 ; }
Detects the IE version. Returns the major version number, or 0 if the browser is not IE.

Simple solution, solely based on UA sniffing. In a better implementation, conditional comments would be used to
detect IE6 to IE9 - see https://gist.github.com/cowboy/542301 for an example. UA sniffing would only serve as a
fallback to detect IE > 9. There are also other solutions to infer the version of IE > 9. For inspiration, see
http://stackoverflow.com/q/17907445/508355.
Detects the IE version . Returns the major version number or 0 if the browser is not IE .