ExtJS method for determining the type of Internet explorer browser

The code is under SRC \core\ext.js in ext

The code for the latest ext3.0beat1 is as follows:

 
ua = navigator.userAgent.toLowerCase(), 
check = function(r){ 
return r.test(ua); 
}, 
isStrict = document.compatMode == "CSS1Compat", 
isOpera = check(/opera/), 
isChrome = check(/chrome/), 
isWebKit = check(/webkit/), 
isSafari = !isChrome && check(/safari/), 
isSafari3 = isSafari && check(/version/3/), 
isSafari4 = isSafari && check(/version/4/), 
isIE = !isOpera && check(/msie/), 
isIE7 = isIE && check(/msie 7/), 
isIE8 = isIE && check(/msie 8/), 
isGecko = !isWebKit && check(/gecko/), 
isGecko3 = isGecko && check(/rv:1.9/), 
isBorderBox = isIE && !isStrict, 
isWindows = check(/windows|win32/), 
isMac = check(/macintosh|mac os x/), 
isAir = check(/adobeair/), 
isLinux = check(/linux/), 
isSecure = /^https/i.test(window.location.protocol); 

Under 2.2.1 (in source\core\ext.js) is

 
var ua = navigator.userAgent.toLowerCase(); 
var isStrict = document.compatMode == "CSS1Compat", 
isOpera = ua.indexOf("opera") > -1, 
isChrome = ua.indexOf("chrome") > -1, 
isSafari = !isChrome && (/webkit|khtml/).test(ua), 
isSafari3 = isSafari && ua.indexOf('webkit/5') != -1, 
isIE = !isOpera && ua.indexOf("msie") > -1, 
isIE7 = !isOpera && ua.indexOf("msie 7") > -1, 
isIE8 = !isOpera && ua.indexOf("msie 8") > -1, 
isGecko = !isSafari && !isChrome && ua.indexOf("gecko") > -1, 
isGecko3 = isGecko && ua.indexOf("rv:1.9") > -1, 
isBorderBox = isIE && !isStrict, 
isWindows = (ua.indexOf("windows") != -1 || ua.indexOf("win32") != -1), 
isMac = (ua.indexOf("macintosh") != -1 || ua.indexOf("mac os x") != -1), 
isAir = (ua.indexOf("adobeair") != -1), 
isLinux = (ua.indexOf("linux") != -1), 
isSecure = window.location.href.toLowerCase().indexOf("https") === 0;