Doing supported browsers check with WhichBrowser.net library.

gistfile1.js

var
	INTERNET_EXPLORER = 'Internet Explorer',
	FIREFOX 	= 'Firefox',
	CHROME 		= 'Chrome',
	OPERA 		= 'Opera',
	OPERA_MINI	= 'Opera Mini',
	SAFARI 		= 'Safari',
	MAXTHON 	= 'Maxthon',
	WEBKIT 		= 'WebKit',
	TRIDENT 	= 'Trident',
	BLINK 		= 'Blink',
	GECKO 		= 'Gecko',
	IOS 		  = 'iOS',
	ANDROID 	= 'Android',
	ua 			  = new WhichBrowser(),
	createAssertFunction = function (test, debug) {
		return function (name, compare, version) {
			return debug
				? function() {
					var result = ua[test].call(ua, name, compare, version);
					if (result) {
						console.warn('Requirement is met: ' + ua + ' | ' + name + ' ' + compare + ' ' + version);
					}
					return result;
				}
				: function () {
					return ua[test].call(ua, name, compare, version);
				}
		}
	},
	debug		= true,
	os 			= createAssertFunction('isOs', debug),
	engine 		= createAssertFunction('isEngine', debug),
	browser 	= createAssertFunction('isBrowser', debug),
	browserTests = [
		[browser(CHROME, '>=', 36)],
		[browser(FIREFOX, '>=', 23)],
		[browser(SAFARI, '>=', 5)],
		[browser(OPERA, '>=', 21)],
		[browser(MAXTHON, '>=', '4.4')],
		[browser(INTERNET_EXPLORER, '>=', 9)],
		[os(IOS, '>=', 6), browser(CHROME, '>=', 36)],
		[os(IOS, '>=', 6), browser(OPERA_MINI, '>=', 8)],
		[os(ANDROID, '>=', 4), browser(CHROME, '>=', 18)]
	],
	engineTests = [
		[engine(BLINK, '>=', 537)],
		[engine(WEBKIT, '>=', 537)],
		[engine(TRIDENT, '>=', 5)],
		[engine(GECKO, '>=', 36)]
	],
	supported = function (tests) {
		for (var i = 0; i < tests.length; i++) {
			var test = tests[i];
			if (Object.prototype.toString.call(test) === '[object Function]') {
				if (test()) {
					return true;
				}
			}
			else if (Object.prototype.toString.call(test) === '[object Array]') {
				if (supported(test)) {
					return true;
				}
			}
			else {
				throw new Error('Unsupported test: ' + test);
			}
		}
		return false;
	};
	
if (supported(browserTests)) {
	// Browser is fully supported
}
else if (supported(engineTests))
 	// Real browsers were not found, well that can happen with Android's default browser for example.
	// In theory, we can test against rendering engine and it still *SHOULD* work.
}