feat(i18n): add Vue.t function

Closes #17

README.md

@@ -152,6 +152,13 @@ Output the following:
 
 Translate the locale of `keypath`. If you specified `lang`, translate the locale of `lang`. If you specified `keypath` of list / named formatting local, you must specify `arguments` too. For `arguments` more details see [Formatting](https://github.com/kazupon/vue-i18n#formatting).
 
+## Vue.t(keypath, [lang], [arguments])
+- keypath: `String` **required**
+- lang: `String` **optional**
+- arguments: `Array | Object` **optional**
+
+This is the same as the `$t` method. This is translate function for global.
+
 
 # Options
 

src/extend.js

@@ -27,15 +27,16 @@ export default function (Vue, locales) {
     return value
   }
 
+
   /**
-   * $t
+   * Vue.t
    *
    * @param {String} key
    * @param {Array} ...args
    * @return {String}
    */
 
-  Vue.prototype.$t = (key, ...args) => {
+  Vue.t = (key, ...args) => {
     if (!key) { return '' }
 
     let language = Vue.config.lang
@@ -57,5 +58,18 @@ export default function (Vue, locales) {
     return getVal(key, language, args)
   }
 
+
+  /**
+   * $t
+   *
+   * @param {String} key
+   * @param {Array} ...args
+   * @return {String}
+   */
+
+  Vue.prototype.$t = (key, ...args) => {
+    return Vue.t(key, ...args)
+  }
+
   return Vue
 }

test/specs/i18n.js

@@ -37,6 +37,93 @@ describe('i18n', () => {
   })
 
 
+  describe('Vue.t', () => {
+    describe('en language locale', () => {
+      it('should translate an english', () => {
+        assert(Vue.t('message.hello') === locales.en.message.hello)
+      })
+    })
+
+    describe('ja language locale', () => {
+      it('should translate a japanese', () => {
+        assert(Vue.t('message.hello', 'ja') === locales.ja.message.hello)
+      })
+    })
+
+    describe('key argument', () => {
+      describe('not specify', () => {
+        it('should return empty string', () => {
+          assert(Vue.t() === '')
+        })
+      })
+
+      describe('empty string', () => {
+        it('should return empty string', () => {
+          assert(Vue.t('') === '')
+        })
+      })
+
+      describe('not regist key', () => {
+        it('should return key string', () => {
+          assert(Vue.t('foo.bar') === 'foo.bar')
+        })
+      })
+
+      describe('sentence fragment', () => {
+        it('should translate fragment', () => {
+          assert(Vue.t('hello world') === 'Hello World')
+        })
+
+        it('should return replaced string if available', () => {
+          assert(
+            Vue.t('Hello {0}', ['kazupon']),
+            'Hello kazupon'
+          )
+        })
+
+        it('should return key if unavailable', () => {
+          assert(Vue.t('Hello') === 'Hello')
+        })
+      })
+    })
+
+    describe('format arguments', () => {
+      context('named', () => {
+        it('should return replaced string', () => {
+          assert(
+            Vue.t('message.format.named', { name: 'kazupon' }),
+            'Hello kazupon, how are you?'
+          )
+        })
+      })
+
+      context('list', () => {
+        it('should return replaced string', () => {
+          assert(
+            Vue.t('message.format.list', ['kazupon']),
+            'Hello kazupon, how are you?'
+          )
+        })
+      })
+    })
+
+    describe('language argument', () => {
+      it('should return empty string', () => {
+        assert(Vue.t('message.hello', 'ja') === locales.ja.message.hello)
+      })
+    })
+
+    describe('format & language arguments', () => {
+      it('should return replaced string', () => {
+        assert(
+          Vue.t('message.format.list', 'ja', ['kazupon']),
+          'こんにちは kazupon, ごきげんいかが？'
+        )
+      })
+    })
+  })
+
+
   describe('$t', () => {
     describe('en language locale', () => {
       it('should translate an english', () => {