From 0bc0a6bc8ccecd4fb453b1799c3c7148770cecad Mon Sep 17 00:00:00 2001
From: long_long_float <niinikazuki@yahoo.co.jp>
Date: Fri, 16 Dec 2016 20:31:03 +0900
Subject: [PATCH] :star: new: locale checking (#98) by @long-long-float

* add $texist

* add document for $texist
---
 gitbook/api.md     | 12 ++++++++++++
 src/extend.js      | 24 ++++++++++++++++++++++++
 test/specs/i18n.js | 20 ++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/gitbook/api.md b/gitbook/api.md
index f151ca2de..e85315cec 100644
--- a/gitbook/api.md
+++ b/gitbook/api.md
@@ -167,3 +167,15 @@
 - **Usage:**
 
   Translate the locale of `keypath` with pluralization. Translate in preferentially component locale than global locale. If not specified component locale, translate with global locale. If you will specify String value to `arguments`, translate the locale of value. If you wll specify Array or Object value to `arguments`, you must specify with `arguments` of [$t](#tkeypath-lang-arguments).
+
+### $texist(keypath, [arguments])
+
+- **Arguments:**
+  - `{String} keypath`
+  - `{Array | Object} [arguments]`
+
+- **Return:**
+  Whether keypath exists (Boolean)
+
+- **Usage:**
+  Return whether key path exists in Boolean.
diff --git a/src/extend.js b/src/extend.js
index 2c4287ae0..0116f0f82 100644
--- a/src/extend.js
+++ b/src/extend.js
@@ -193,5 +193,29 @@ export default function (Vue) {
     return fetchChoice(this.$t(key, ...args), choice)
   }
 
+  /**
+   * $texist
+   *
+   * @param {String} key
+   * @param {Array} ...args
+   * @return {Boolean}
+   *
+   */
+
+  Vue.prototype.$texist = function (key, ...args) {
+    if (!key) { return false }
+    const { lang, fallback, params } = parseArgs(...args)
+
+    let locale
+    if (this.$options.locales) {
+      locale = bind(getComponentLocale, this)
+    } else {
+      locale = getAssetLocale
+    }
+
+    const result = translate(locale, lang, fallback, key, params)
+    return !isNil(result)
+  }
+
   return Vue
 }
diff --git a/test/specs/i18n.js b/test/specs/i18n.js
index c8914a2bc..fe91ea5cc 100644
--- a/test/specs/i18n.js
+++ b/test/specs/i18n.js
@@ -487,6 +487,26 @@ describe('i18n', () => {
     })
   })
 
+  describe('$texist', () => {
+    describe('existing key', () => {
+      it('should return true', () => {
+        const vm = new Vue()
+        assert.equal(vm.$texist('message.hello'), true)
+      })
+
+      it('should return true with language', () => {
+        const vm = new Vue()
+        assert.equal(vm.$texist('message.hello', 'ja'), true)
+      })
+    })
+
+    describe('not existing key', () => {
+      it('should return false', () => {
+        const vm = new Vue()
+        assert.equal(vm.$texist('message.hallo'), false)
+      })
+    })
+  })
 
   describe('reactive translation', () => {
     let el