Add comments to JavaScript to make it more readable.

modules/core/ui/location/js/locations_drag_and_drop.js

@@ -12,12 +12,15 @@
 
   Drupal.behaviors.locationsDragAndDrop = {
     attach: function (context, settings) {
+
+      // Function for toggling drag and drop.
       var toggleDragAndDrop = function() {
         $('input#edit-save').attr('disabled', !dragAndDropEnabled)
         $('input#edit-reset').attr('disabled', !dragAndDropEnabled)
         domTree.config.dragAndDrop.enabled = dragAndDropEnabled
       }
 
+      // Enable Inspire Tree.
       var tree = new InspireTree({
         data: settings.asset_tree,
       })
@@ -27,8 +30,11 @@
       })
       tree.nodes().expand()
 
+      // Start with drag and drop disabled.
       var dragAndDropEnabled = false
       toggleDragAndDrop()
+
+      // Toggle drag and drop when the button is clicked.
       $('input#edit-toggle').on('click', function(event) {
         event.preventDefault()
         dragAndDropEnabled = !dragAndDropEnabled
@@ -37,9 +43,17 @@
         domTree.attach($('.locations-tree'));
       })
 
+      // Maintain a list of hierarchy changes as items are moved.
       var changes = {}
       tree.on('node.drop', function(event, source, target, index) {
+
+        // Determine the new parent. If target is null, then it means that the
+        // child was moved to the root context, which either means the child
+        // will no longer have a parent, or if we are in the context of a
+        // specific asset's children, that asset will become the new parent.
         var new_parent = (target === null) ? settings.asset_parent : target.asset_id
+
+        // Create a change record, if one doesn't already exist.
         if (!changes.hasOwnProperty(source.id)) {
           if (source.original_parent !== new_parent) {
             changes[source.id] = {
@@ -49,6 +63,10 @@
             }
           }
         }
+
+        // Otherwise, if a change record already exists, we will either update
+        // it, or delete it (if the child is changing back to its original
+        // parent, in which case a change is no longer necessary).
         else {
           if (changes[source.id].original_parent !== new_parent) {
             changes[source.id].new_parent = new_parent
@@ -57,9 +75,12 @@
             delete changes[source.id]
           }
         }
+
+        // Save the change records as a JSON string in the hidden input field.
         $('input[name=changes]').val(JSON.stringify(changes))
       })
 
+      // Link to locations when drag and drop is disabled.
       tree.on('node.click', function(event, node) {
         event.preventDefault()
         if (node.url && !dragAndDropEnabled) {