What's the correct way to pass variables to the JavaScript of a custom CKEditor plugin? I saw that we can pass values to our JavaScript using drupalSettings. However, this is for Drupal custom module JavaScript files. Since a CKEditor plugin file is already attached/loaded in a different way, I am wondering what's the correct way to pass variables to it.

The following is the code that I made, according to the example, but I have the feeling that plugin.js is loaded two times:  


one time in inline_comment_preprocess_html()
and one more time with inline_comment/src/Plugin/CKEditorPlugin/InlineComment.php


What's the correct way to pass variables to plugin.js?  

inline_comment.info.yml

name: CKEditor Inline Comment
type: module
description: "Adds the Inline Comment plugin to CKEditor."
package: CKEditor

dependencies:
  - ckeditor
  - core/jquery
  - core/drupalSettings

version: '8.x-1.0'
core: '8.x'
project: 'inline_comment'


inline_comment.module

function inline_comment_preprocess_html(&amp;$variables) {
  $lotus_height = '300px';
  $variables['#attached']['library'][] = 'js/plugins/inline_comment/plugin.js'; // I think I shouldn't try to load plugin.js two times
  $variables['#attached']['drupalSettings']['lotus']['lotusJS']['lotus_height'] = $lotus_height;

}


js/plugins/inline_comment/plugin.js

CKEDITOR.plugins.add('inline_comment', {
    //...
});

(function ($, Drupal, drupalSettings) {
    Drupal.behaviors.LotusBehavior = {
        attach: function (context, settings) {
            var lotusHeight = drupalSettings.lotus.lotusJS.lotus_height;
            console.log('lotusHeight' + lotusHeight);
        }
    };
})(jQuery, Drupal, drupalSettings);


I noticed if I remove the line with $variables['#attached']['library'][] and I dump($variables) there is no drupalSettings variable in #attached array.
You can pass options via getConfig option of the class that creates the plugin. See how the module "Color Button" does it:

https://cgit.drupalcode.org/colorbutton/tree/src/Plugin/CKEditorPlugin/ColorButton.php?h=8.x-1.x

This is passed along to the defined plugin when it is loaded up (the one defined in getFile.) 

See: https://api.drupal.org/api/drupal/core%21modules%21ckeditor%21src%21CKEditorPluginBase.php/class/CKEditorPluginBase/8.6.x

and:

https://api.drupal.org/api/drupal/core%21modules%21ckeditor%21src%21CKEditorPluginInterface.php/function/CKEditorPluginInterface%3A%3AgetConfig/8.6.x

The variable names passed or modified in getConfig need to be the same names as the ones in the plugin to be overwritten.