Add helper function for reordering

Signed-off-by: Julius Härtl <jus@bitgrid.net>

src/helpers/applyOrderToArray.js

@@ -0,0 +1,39 @@
+/*
+ * @copyright Copyright (c) 2018 Julius Härtl <jus@bitgrid.net>
+ *
+ * @author Julius Härtl <jus@bitgrid.net>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+const arrayMove = function(arrayToSort, removedIndex, addedIndex) {
+	if (removedIndex === null && addedIndex === null) return arrayToSort
+
+	const result = [...arrayToSort]
+	let itemToAdd = arrayToSort[removedIndex]
+
+	if (removedIndex !== null) {
+		itemToAdd = result.splice(removedIndex, 1)[0]
+	}
+
+	if (addedIndex !== null) {
+		result.splice(addedIndex, 0, itemToAdd)
+	}
+	return result
+}
+
+export default arrayMove