review https://www.drupal.org/node/2830882#comment-12073129

Author: tedbow

core/misc/dialog/dialog.js

@@ -75,8 +75,8 @@
         openDialog({modal: true});
       },
       close: closeDialog,
-      container: getContainer,
-      options: setOptions,
+      getContainer: getContainer,
+      setOptions: setOptions,
       handleDialogResize: handleDialogResize
     };
 
@@ -97,12 +97,29 @@
       $(window).trigger('dialog:afterclose', [dialog, $element]);
     }
 
+    /**
+     * Gets the HTMLElement that contains the dialog.
+     *
+     * jQuery UI dialogs are contained in outer HTMLElement.
+     * For themes or modules that override the Drupal.dialog with non jQuery UI
+     * dialogs that do not have a containing element other than the dialog
+     * itself should just return the dialog element.
+     *
+     * @return {HTMLElement} element
+     *   The HTMLElement that contains the dialog.
+     */
     function getContainer() {
       return $element.dialog('widget')[0];
     }
 
-    function setOptions($options) {
-      $element.dialog('option', $options);
+    /**
+     * Sets the options for the dialog.
+     *
+     * @param {object} options
+     *   jQuery UI options to be passed to the dialog.
+     */
+    function setOptions(options) {
+      $element.dialog('option', options);
     }
 
     /**

core/modules/outside_in/js/off-canvas.js

@@ -34,7 +34,7 @@
     var offsets = displace.offsets;
     var $element = event.data.$element;
     var dialog = event.data.dialog;
-    var $container = $(dialog.container());
+    var $container = $(dialog.getContainer());
 
     var adjustedOptions = {
       // @see http://api.jqueryui.com/position/
@@ -50,7 +50,7 @@
       height: ($(window).height() - (offsets.top + offsets.bottom)) + 'px'
     });
 
-    dialog.options(adjustedOptions);
+    dialog.setOptions(adjustedOptions);
     $element.trigger('dialogContentResize.off-canvas');
   }
 
@@ -66,7 +66,7 @@
     if ($('body').outerWidth() < minDisplaceWidth) {
       return;
     }
-    var $container = $(event.data.dialog.container());
+    var $container = $(event.data.dialog.getContainer());
 
     var width = $container.outerWidth();
     var mainCanvasPadding = $mainCanvasWrapper.css('padding-' + edge);
@@ -100,7 +100,7 @@
               .on('dialogContentResize.off-canvas', eventData, debounce(bodyPadding, 100))
               .trigger('dialogresize.off-canvas');
 
-            $(dialog.container()).attr('data-offset-' + edge, '');
+            $(dialog.getContainer()).attr('data-offset-' + edge, '');
 
             $(window)
                 .on('resize.off-canvas scroll.off-canvas', eventData, debounce(resetSize, 100))