Add "has" method for checking if keys exist (#38)

index.js

@@ -115,6 +115,22 @@ class I18n {
             ) || I18n.getDefault(...keys);
     }
 
+    /**
+     * Check if a translation key exists
+     * @param  {string|string[]} keys
+     * @param  {Object}          data
+     * @return {Boolean}      [description]
+     */
+    has(keys, data) {
+        keys = Array.isArray(keys) ? keys : [ keys ];
+        const alternatives = keys.reduce(
+            (accumulator, key) => accumulator.concat(this.alternatives(key, data)),
+            []
+        );
+
+        return typeof this.find(...alternatives) !== 'undefined';
+    }
+
     /**
      * Create key alternatives with prefixes according to instance scopes
      * @param  {string}   key

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@fiverr/i18n",
-  "version": "1.7.0",
+  "version": "1.8.0",
   "description": "Translation helper",
   "keywords": [
     "i18n",

readme.md

@@ -185,3 +185,12 @@ require('@fiverr/i18n/singleton');
 // i18n is defined globally
 ```
 
+### Helper functions
+Check if a key is available (including empty strings)
+#### has
+```js
+i18n.has('key');
+i18n.has(['key', 'other_key']);
+i18n.has('namespace.key');
+i18n.has('key', { $scope: 'namespace' });
+```

tests/index.js

@@ -150,4 +150,38 @@ describe('I18n', () => {
 
         expect(i18n.translate('i.am.in.scope')).to.equal('I am in scope');
     });
+
+    it('searches for available keys', () => {
+        const i18n = new I18n();
+
+        i18n.add({
+            lookup: { key: 'balue', biscuit: '' }
+        });
+
+        [
+            [ 'lookup.key' ],
+            [ 'lookup.biscuit' ],
+            [ ['lookup.pie', 'lookup.key'] ],
+            [ 'key', { $scope: 'lookup' } ],
+            [ [ 'pie', 'key' ], { $scope: 'lookup' } ]
+        ].forEach(
+            (args) => expect(i18n.has(...args), args).to.be.true
+        );
+
+        [
+            [ 'lookup.pie' ],
+            [ ['lookup.pie', 'lookup.cake'] ],
+            [ 'key' ],
+            [],
+            [ null ]
+        ].forEach(
+            (args) => expect(i18n.has(...args), args).to.be.false
+        );
+
+        const child = i18n.spawn('lookup');
+
+        expect(child.has('key'), 'child.key').to.be.true;
+        expect(child.has('biscuit'), 'child.biscuit').to.be.true;
+        expect(child.has('pie'), 'child.pie').to.be.false;
+    });
 });