gistfile1.js

// ----------------------------------------------------------
// A short snippet for detecting versions of IE:
// Uses a combination of object detection and user-agent 
// sniffing.
// ----------------------------------------------------------
// If you're not in IE then:
//     ie === NaN  // falsy
// If you're in IE then you can determine which version:
//     ie === 7; // IE7
// Thus, to detect IE:
//     if (ie) {}
// And to detect the version:
//     ie === 6 // IE6
//     ie > 7 // IE8, IE9 ...
//     ie < 9 // Anything less than IE9
// ----------------------------------------------------------


var ie = ( !!window.ActiveXObject && +( /msie\s(\d+)/i.exec( navigator.userAgent )[1] ) ) || NaN;

ie-mobile-detect.js

// The same thing but for IE Mobile instead.

var ieMobile = ( !! window.ActiveXObject && +( /IEMobile\/(\d+\.?(\d+)?)/.exec( navigator.userAgent )[1] ) ) || NaN;