Fallback to language-only file if language_territory file DNE

README.md

@@ -52,6 +52,9 @@ Create an instance of y18n with the config provided, options include:
 * `directory`: the locale directory, default `./locales`.
 * `updateFiles`: should newly observed strings be updated in file, default `true`.
 * `locale`: what locale should be used.
+* `fallbackToLanguage`: should fallback to a language-only file (e.g. `en.json`)
+  be allowed if a file matching the locale does not exist (e.g. `en_US.json`),
+  default `true`.
 
 ### y18n.\_\_(str, arg, arg, arg)
 

index.js

@@ -8,6 +8,7 @@ function Y18N (opts) {
   this.directory = opts.directory || './locales'
   this.updateFiles = typeof opts.updateFiles === 'boolean' ? opts.updateFiles : true
   this.locale = opts.locale || 'en'
+  this.fallbackToLanguage = typeof opts.fallbackToLanguage === 'boolean' ? opts.fallbackToLanguage : true
 
   // internal stuff.
   this.cache = {}
@@ -53,7 +54,7 @@ Y18N.prototype._processWriteQueue = function () {
   var locale = work[1]
   var cb = work[2]
 
-  var languageFile = path.resolve(directory, './', locale + '.json')
+  var languageFile = this._resolveLocaleFile(directory, locale)
   var serializedLocale = JSON.stringify(this.cache[locale], null, 2)
 
   fs.writeFile(languageFile, serializedLocale, 'utf-8', function (err) {
@@ -65,7 +66,7 @@ Y18N.prototype._processWriteQueue = function () {
 
 Y18N.prototype._readLocaleFile = function () {
   var localeLookup = {}
-  var languageFile = path.resolve(this.directory, './', this.locale + '.json')
+  var languageFile = this._resolveLocaleFile(this.directory, this.locale)
 
   try {
     localeLookup = JSON.parse(fs.readFileSync(languageFile, 'utf-8'))
@@ -81,6 +82,26 @@ Y18N.prototype._readLocaleFile = function () {
   this.cache[this.locale] = localeLookup
 }
 
+Y18N.prototype._resolveLocaleFile = function (directory, locale) {
+  var file = path.resolve(directory, './', locale + '.json')
+  if (this.fallbackToLanguage && !this._fileExistsSync(file) && ~locale.lastIndexOf('_')) {
+    // attempt fallback to language only
+    var languageFile = path.resolve(directory, './', locale.split('_')[0] + '.json')
+    if (this._fileExistsSync(languageFile)) file = languageFile
+  }
+  return file
+}
+
+// this only exists because fs.existsSync() "will be deprecated"
+// see https://nodejs.org/api/fs.html#fs_fs_existssync_path
+Y18N.prototype._fileExistsSync = function (file) {
+  try {
+    return fs.statSync(file).isFile()
+  } catch (err) {
+    return false
+  }
+}
+
 Y18N.prototype.__n = function () {
   var args = Array.prototype.slice.call(arguments)
   var singular = args.shift()

test/y18n-test.js

@@ -46,6 +46,36 @@ describe('y18n', function () {
       __('Hello').should.equal('Avast ye mateys!')
     })
 
+    it('uses language file if language_territory file does not exist', function () {
+      var __ = y18n({
+        locale: 'pirate_JM',
+        directory: __dirname + '/locales'
+      }).__
+
+      __('Hello').should.equal('Avast ye mateys!')
+    })
+
+    it('does not fallback to language file if fallbackToLanguage is false', function () {
+      var __ = y18n({
+        locale: 'pirate_JM',
+        fallbackToLanguage: false,
+        updateFiles: false,
+        directory: __dirname + '/locales'
+      }).__
+
+      __('Hello').should.equal('Hello')
+    })
+
+    it('uses strings as given if no matching locale files found', function () {
+      var __ = y18n({
+        locale: 'zz_ZZ',
+        updateFiles: false,
+        directory: __dirname + '/locales'
+      }).__
+
+      __('Hello').should.equal('Hello')
+    })
+
     it('expands arguments into %s placeholders', function () {
       var __ = y18n({
         directory: __dirname + '/locales'
@@ -56,7 +86,7 @@ describe('y18n', function () {
 
     describe('the first time observing a word', function () {
       beforeEach(function (done) {
-        rimraf('./test/locales/fr.json', function () {
+        rimraf('./test/locales/fr*.json', function () {
           return done()
         })
       })
@@ -72,17 +102,57 @@ describe('y18n', function () {
 
       it('writes new word to locale file if updateFiles is true', function (done) {
         var __ = y18n({
-          locale: 'fr',
+          locale: 'fr_FR',
+          directory: __dirname + '/locales'
+        }).__
+
+        __('banana', function (err) {
+          var locale = JSON.parse(fs.readFileSync('./test/locales/fr_FR.json', 'utf-8'))
+          locale.banana.should.equal('banana')
+          return done(err)
+        })
+      })
+
+      it('writes new word to language file if language_territory file does not exist', function (done) {
+        fs.writeFileSync('./test/locales/fr.json', '{"meow": "le meow"}', 'utf-8')
+
+        var __ = y18n({
+          locale: 'fr_FR',
           directory: __dirname + '/locales'
         }).__
 
+        __('meow').should.equal('le meow')
         __('banana', function (err) {
           var locale = JSON.parse(fs.readFileSync('./test/locales/fr.json', 'utf-8'))
           locale.banana.should.equal('banana')
           return done(err)
         })
       })
 
+      it('writes word to missing locale file, if no fallback takes place', function (done) {
+        fs.writeFileSync('./test/locales/fr.json', '{"meow": "le meow"}', 'utf-8')
+
+        var __ = y18n({
+          locale: 'fr_FR',
+          fallbackToLanguage: false,
+          directory: __dirname + '/locales'
+        }).__
+
+        __('banana', function (err) {
+          // 'banana' should be written to fr_FR.json
+          var locale = JSON.parse(fs.readFileSync('./test/locales/fr_FR.json', 'utf-8'))
+          locale.should.deep.equal({
+            banana: 'banana'
+          })
+          // fr.json should remain untouched
+          var frJson = JSON.parse(fs.readFileSync('./test/locales/fr.json', 'utf-8'))
+          frJson.should.deep.equal({
+            meow: 'le meow'
+          })
+          return done(err)
+        })
+      })
+
       it('handles enqueuing multiple writes at the same time', function (done) {
         var __ = y18n({
           locale: 'fr',