user agent
// See also: https://github.com/azer/environ
//http://nextmarvel.net/blog/2011/02/one-line-javascript-browser-detection/
var IE6 = /msie 6/i.test(navigator.userAgent),
IE7 = /msie 7/i.test(navigator.userAgent),
IE8 = /msie 8/i.test(navigator.userAgent),
IE9 = /msie 9/i.test(navigator.userAgent),
IE10 = /msie 9/i.test(navigator.userAgent),
SAFARI = /safari/i.test(navigator.userAgent),
FIREFOX = /firefox/i.test(navigator.userAgent),
CHROME = /chrome/i.test(navigator.userAgent),
IPHONE = /iphone/i.test(navigator.userAgent),
MAC = /mac/i.test(navigator.userAgent),
WINDOWS = /win/i.test(navigator.appVersion),
LINUX = /linux/i.test(navigator.appVersion),
UNIX = /X11/i.test(navigator.appVersion),
KINDLE = /kindle/i.test(navigator.userAgent);