Example of dojo/sniff

gistfile1.js

define(["./has"], function(has){
	if(!has("host-browser")){
		return {};
	}

	var hasAdd = has.add,
		n = navigator,
		dua = n.userAgent,
		dav = n.appVersion,
		tv = parseFloat(dav),
		isOpera,
		isAIR,
		isKhtml,
		isWebKit,
		isChrome,
		isMac,
		isSafari,
		isMozilla ,
		isMoz,
		isIE,
		isFF,
		isQuirks,
		isIos,
		isAndroid,
		isWii;

	// fill in the rendering support information in dojo.render.*
	if(dua.indexOf("AdobeAIR") >= 0){ isAIR = 1; }
	isKhtml = (dav.indexOf("Konqueror") >= 0) ? tv : 0;
	isWebKit = parseFloat(dua.split("WebKit/")[1]) || undefined;
	isChrome = parseFloat(dua.split("Chrome/")[1]) || undefined;
	isMac = dav.indexOf("Macintosh") >= 0;
	isIos = /iPhone|iPod|iPad/.test(dua);
	isAndroid = parseFloat(dua.split("Android ")[1]) || undefined;
	isWii = typeof opera != "undefined" && opera.wiiremote;

	// safari detection derived from:
	//		http://developer.apple.com/internet/safari/faq.html#anchor2
	//		http://developer.apple.com/internet/safari/uamatrix.html
	var index = Math.max(dav.indexOf("WebKit"), dav.indexOf("Safari"), 0);
	if(index && !isChrome){
		// try to grab the explicit Safari version first. If we don't get
		// one, look for less than 419.3 as the indication that we're on something
		// "Safari 2-ish".
		isSafari = parseFloat(dav.split("Version/")[1]);
		if(!isSafari || parseFloat(dav.substr(index + 7)) <= 419.3){
			isSafari = 2;
		}
	}

	if (!has("dojo-webkit")) {
		if(dua.indexOf("Opera") >= 0){
			isOpera = tv;
			// see http://dev.opera.com/articles/view/opera-ua-string-changes and http://www.useragentstring.com/pages/Opera/
			// 9.8 has both styles; <9.8, 9.9 only old style
			if(isOpera >= 9.8){
				isOpera = parseFloat(dua.split("Version/")[1]) || tv;
			}
		}

		if(dua.indexOf("Gecko") >= 0 && !isKhtml && !isWebKit){
			isMozilla = isMoz = tv;
		}
		if(isMoz){
			//We really need to get away from this. Consider a sane isGecko approach for the future.
			isFF = parseFloat(dua.split("Firefox/")[1] || dua.split("Minefield/")[1]) || undefined;
		}
		if(document.all && !isOpera){
			isIE = parseFloat(dav.split("MSIE ")[1]) || undefined;
			//In cases where the page has an HTTP header or META tag with
			//X-UA-Compatible, then it is in emulation mode.
			//Make sure isIE reflects the desired version.
			//document.documentMode of 5 means quirks mode.
			//Only switch the value if documentMode's major version
			//is different from isIE's major version.
			var mode = document.documentMode;
			if(mode && mode != 5 && Math.floor(isIE) != mode){
				isIE = mode;
			}
		}
	}

	isQuirks = document.compatMode == "BackCompat";

	hasAdd("opera", isOpera);
	hasAdd("air", isAIR);
	hasAdd("khtml", isKhtml);
	hasAdd("webkit", isWebKit);
	hasAdd("chrome", isChrome);
	hasAdd("mac", isMac );
	hasAdd("safari", isSafari);
	hasAdd("mozilla", isMozilla );
	hasAdd("ie", isIE );
	hasAdd("ff", isFF);
	hasAdd("quirks", isQuirks);
	hasAdd("ios", isIos);
	hasAdd("android", isAndroid);

	return {
		browser: true,
		opera: isOpera,
		AIR: isAIR,
		khtml: isKhtml,
		webkit: isWebKit,
		chrome: isChrome,
		mac: isMac,
		safari: isSafari,
		mozilla: isMozilla,
		ie: isIE,
		ff: isFF,
		quirks: isQuirks,
		ios: isIos,
		android: isAndroid,
		locale:  (isIE ? n.userLanguage : n.language).toLowerCase()
	};
});