diff --git a/js/office_hours.js b/js/office_hours.js
index 8816efb..87fd1f3 100644
--- a/js/office_hours.js
+++ b/js/office_hours.js
@@ -92,6 +92,7 @@

     // Show the next slot item, slowly.
     const nextSlot = $(this).closest('tr').next();
+    nextSlot.removeClass('js-office-hours-hide');
     nextSlot.fadeIn('slow');

     fixStriping($(this).parents('.field--type-office-hours'));
@@ -126,6 +127,13 @@
     // Clear the comment.
     slot.find('.form-text').each(clearValue);

+    slot.addClass('js-office-hours-hide');
+    slot.fadeOut('slow');
+
+    const previousSelector = $(this).closest('tr').prev();
+    previousSelector.find('[data-drupal-selector$=add]')
+      .show();
+
     // @todo Hide subsequent slot that is cleared.
   }

@@ -204,7 +212,7 @@

   Drupal.behaviors.office_hours = {
     attach: function doUpdateElement(context) {
-     $(document).ready(function prepareElements() {
+     $(once('office-hours', '.field--type-office-hours', context)).each(function prepareElements() {
         // Attach a function to each JS link and initialize if needed.
         // N.B.: using * wildcard, since initially, no suffix is added,
         // but after 'Add exception'button, a suffix is added to the ID.