Issue #3197651: Select / Unselect All taxonomies, blocks, or menus

js/select-unselect-all.js

+/**
+ * @file
+ * function to select and unselect all entities.
+ */
+
+(function (Drupal, $, once) {
+
+  'use strict';
+
+  /**
+   * Uncheck all checkboxes.
+   *
+   * @type {{attach: Drupal.behaviors.unselectAll.attach}}
+   */
+  Drupal.behaviors.unselectAll = {
+    attach: function (context, settings) {
+      once('selectUnselectAll', '.form-checkboxes', context).forEach(function (checkboxes) {
+        // Set up a prototype link.
+        let selAll = Drupal.t('Select All'),
+          selNone = Drupal.t('Unselect All'),
+          link = $('<a class="select-unselect-all" href="#">' + selNone + '</a>');
+
+        $(checkboxes).prepend(link);
+
+        // Set an event handler.
+        link.click(function (event) {
+          // Don't follow the link.
+          event.preventDefault();
+          event.stopPropagation();
+
+          let check = $(this).text() === selAll;
+          $(this)
+            .html(check ? selNone : selAll)
+            .siblings('.form-type--checkbox')
+            .find('input:checkbox')
+            .prop('checked', check);
+        });
+
+      });
+    },
+  };
+
+})(Drupal, jQuery, once);