I need to install extra plugins such as: youtube, table of contents and other. Download plugin from official web site https://ckeditor.com/cke4/addon/youtube put in directory /mysite/core/modules/ckeditor/js/plugins and enable the plugin by changing or adding the extraPlugins line in your configuration (config.js):

config.extraPlugins = 'youtube';

But I didn't found file config.js. Where I must add this string, for getting these plugins work?


Yes. For youtube  have alternatives, but Ckeditor have many plugins, and unfortunately not all plugins have alternative in backdrop cms. For example Table of Content for some projects is very usefull, and for now we don't have any choice. I hope in the future will port more modules...