Add frequently utils

Store and returns frequently used emojis.
If not already in the frequently used, last used emoji will always be added to the array.

src/utils/frequently.js

@@ -0,0 +1,28 @@
+import {store} from '.'
+
+let frequently = store.get('frequently') || {}
+
+function add(emoji) {
+  var { id } = emoji
+
+  frequently[id] || (frequently[id] = 0)
+  frequently[id] += 1
+
+  store.set('last', id)
+  store.set('frequently', frequently)
+}
+
+function get(quantity) {
+  var sorted = Object.keys(frequently).sort((a, b) => frequently[a] - frequently[b]).reverse(),
+      sliced = sorted.slice(0, quantity),
+      last = store.get('last')
+
+  if (last && sliced.indexOf(last) == -1) {
+    sliced.pop()
+    sliced.push(last)
+  }
+
+  return sliced
+}
+
+export default { add, get }

src/utils/index.js

@@ -1 +1,2 @@
 export {default as store} from './store'
+export {default as frequently} from './frequently'