Merge pull request #493 from PanAeon/feature/generate-alternate-urls

Generate alternate url for different locales so search engine could find them all.

src/js/app/index.js

@@ -86,6 +86,23 @@ var vcsModeRefresh = function(eventData) {
   $('body').toggleClass('hgMode', !isGit);
 };
 
+var insertAlternateLinks = function(pageId) {
+  // For now pageId is null, which would link to the main page.
+  // In future if pageId is provided this method should link to a specific page
+
+  // The value of the hreflang attribute identifies the language (in ISO 639-1 format)
+  // and optionally a region (in ISO 3166-1 Alpha 2 format) of an alternate URL
+
+  var altLinks = LocaleStore.getSupportedLocales().map(function(langCode) {
+    var url = "https://learngitbranching.js.org/?locale=" + langCode;
+    return '<link rel="alternate" hreflang="'+langCode+'" href="' + url +'" />';
+  });
+  var defaultUrl = "https://learngitbranching.js.org/?locale=" + LocaleStore.getDefaultLocale();
+  altLinks.push('<link rel="alternate" hreflang="x-default" href="' + defaultUrl +'" />');
+  $('head').prepend(altLinks);
+
+};
+
 var intlRefresh = function() {
   if (!window.$) { return; }
   var countryCode = LocaleStore.getLocale().split("_")[0];
@@ -252,6 +269,8 @@ var initDemo = function(sandbox) {
     tryLocaleDetect();
   }
 
+  insertAlternateLinks();
+
   if (params.command) {
     var command = unescape(params.command);
     sandbox.mainVis.customEvents.on('gitEngineReady', function() {

src/js/stores/LocaleStore.js

@@ -30,6 +30,10 @@ var headerLocaleMap = {
   'pt-BR': 'pt_BR'
 };
 
+var supportedLocalesList = Object.values(langLocaleMap)
+                                 .concat(Object.values(headerLocaleMap))
+                                 .filter(function (value, index, self) { return self.indexOf(value) === index;});
+
 function _getLocaleFromHeader(langString) {
   var languages = langString.split(',');
   var desiredLocale;
@@ -73,6 +77,10 @@ AppConstants.StoreSubscribePrototype,
     return _locale;
   },
 
+  getSupportedLocales: function() {
+    return supportedLocalesList.slice();
+  },
+
   dispatchToken: AppDispatcher.register(function(payload) {
     var action = payload.action;
     var shouldInform = false;