Add callback for handling sorted repeater items

modules/backend/formwidgets/Repeater.php

@@ -322,6 +322,11 @@ class Repeater extends FormWidgetBase
         return $widget->onRefresh();
     }
 
+    public function onReorder()
+    {
+        // Handle reordering of repeater items
+    }
+
     //
     // Group mode
     //

modules/backend/formwidgets/repeater/assets/js/repeater.js

@@ -35,6 +35,7 @@
 
     Repeater.DEFAULTS = {
         sortableHandle: '.repeater-item-handle',
+        sortableHandler: null,
         sortableContainer: 'ul.field-repeater-items',
         titleFrom: null,
         minItems: null,
@@ -232,13 +233,20 @@
     Repeater.prototype.onSortStart = function($item, container, callback, event) {
         this.sortingStartIndex = $item.index()
 
-        callback($item, container, callback, event);
+        callback($item, container, callback, event)
     }
 
     Repeater.prototype.onSortStop = function($item, container, callback, event) {
         var endIndex = $item.index()
 
-        callback($item, container, callback, event);
+        this.$el.request(this.options.sortableHandler, {
+            data: {
+                _repeater_index: this.sortingStartIndex,
+                _repeater_new_index: endIndex
+            }
+        })
+
+        callback($item, container, callback, event)
     }
 
     // FIELD REPEATER PLUGIN DEFINITION

modules/backend/formwidgets/repeater/partials/_repeater.htm

@@ -3,6 +3,7 @@
      <?= $titleFrom ? 'data-title-from="'.$titleFrom.'"' : '' ?>
      <?= $minItems ? 'data-min-items="'.$minItems.'"' : '' ?>
      <?= $maxItems ? 'data-max-items="'.$maxItems.'"' : '' ?>
+     data-sortable-handler="<?= $this->getEventHandler('onReorder') ?>"
      data-sortable-container="#<?= $this->getId('items') ?>"
      data-sortable-handle=".<?= $this->getId('items') ?>-handle">