Detect Internet Explorer and version.

gistfile1.js

// ----------------------------------------------------------
// If you're not in IE (or IE version is less than 5) then:
// isIE === undefined
// If you're in IE (>=5) then you can determine which version:
// isIE === 7; // IE7
// Thus, to detect IE:
// if (isIE) {}
// And to detect the version:
// isIE === 6 // IE6
// isIE > 7 // IE8, IE9, IE10 ...
// isIE < 9 // Anything less than IE9
// ----------------------------------------------------------
// Credits http://stackoverflow.com/a/16657946
// ----------------------------------------------------------
var isIE = (function(){
    var undef,rv = -1; // Return value assumes failure.
    if (navigator.appName == 'Microsoft Internet Explorer')
    {
        var ua = navigator.userAgent;
        var re  = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
        if (re.exec(ua) != null)
            rv = parseFloat( RegExp.$1 );
    }

    return ((rv > -1) ? rv : undef);
}());