let i18nextBrowserLanguageDetector detect the lang

js/index.js

@@ -11,6 +11,27 @@
 		return results === null ? '' : decodeURIComponent(results[1].replace(/\+/g, ' '));
 	};
 
+	MyApp.Utils.removeURLParameter = function(url, parameter) {
+		//prefer to use l.search if you have a location/link object
+		var urlparts = url.split('?');
+		if (urlparts.length >= 2) {
+
+			var prefix = encodeURIComponent(parameter) + '=';
+			var pars = urlparts[1].split(/[&;]/g);
+
+			//reverse iteration as may be destructive
+			for (var i = pars.length; i-- > 0;) {
+				//idiom for string.startsWith
+				if (pars[i].lastIndexOf(prefix, 0) !== -1) {
+					pars.splice(i, 1);
+				}
+			}
+
+			return urlparts[0] + (pars.length > 0 ? '?' + pars.join('&') : '');
+		}
+		return url;
+	};
+
 
 	// app functions
 	MyApp.renderShell = function() {
@@ -61,8 +82,17 @@
 	// app startup
 
 	// set language
-	i18next.init({
+	i18next
+	.use(i18nextBrowserLanguageDetector)
+	.init({
 		lng: MyApp.config.lang,
+		detection: {
+			order: ['querystring', 'cookie', 'navigator'],
+			lookupQuerystring: 'lang',
+			lookupCookie: 'current-language',
+			caches: ['cookie'],
+			cookieMinutes: 5256000
+		},
 		resources: {
 			en: {
 				translation: {
@@ -86,6 +116,13 @@
 	})
 	.then(function() {
 		// language initialized
+		// if there is a lang query string parameter, remove it and reload: we save the language in a cookie so the url stays nice
+		if (MyApp.Utils.getUrlParameter('lang')) {
+			var newUrl = MyApp.Utils.removeURLParameter(window.location.toString(), 'lang');
+			//removeURLParameter does not return the hash. add it back if there is one.
+			newUrl = newUrl + window.location.hash;
+			window.location = newUrl;
+		}
 
 		// render main shell
 		MyApp.renderShell()