Breaking: #96874 - CKEditor-related plugins and configuration

Description

TYPO3 v12 ships with CKEditor 5, which is a completely new, rewritten editor compared to CKEditor 4 which was shipped since TYPO3 v8.

Any kind of plugin, which was written for CKEditor4 is not compatible anymore.

In addition, since CKEditor 5 does not grant HTML input the same way as before.

Impact

Any plugin in CKEditor will not be loaded anymore in TYPO3 v12.

It might be possible to have data loss when editing and saving data, especially since some configuration formats have been changed.

Affected installations

TYPO3 installations with custom extensions extending CKEditor with plugins, or relying on a specific logic to save data with specific contents (such as additional allowed HTML tags).

Migration

In general, it is advised to read the CKEditor 4 to 5 migration to understand the conceptual changes, also related to plugins.

Writing a custom plugin for CKEditor 5 can be done in TypeScript or JavaScript, using the CKEditor5 plugin system.

Example - A timestamp plugin @my-vendor/my-package/timestamp-plugin.js which adds a toolbar item to add the current timestamp into the editor.

import { Plugin } from '@ckeditor/ckeditor5-core';
import { ButtonView } from '@ckeditor/ckeditor5-ui';

export class Timestamp extends Plugin {
  static pluginName = 'Timestamp';

  init() {
    const editor = this.editor;

    // The button must be registered among the UI components of the editor
    // to be displayed in the toolbar.
    editor.ui.componentFactory.add(Timestamp.pluginName, () => {
      // The button will be an instance of ButtonView.
      const button = new ButtonView();

      button.set({
        label: 'Timestamp',
        withText: true
      });

      // Execute a callback function when the button is clicked
      button.on('execute', () => {
        const now = new Date();

        // Change the model using the model writer
        editor.model.change(writer => {

          // Insert the text at the user's current position
          editor.model.insertContent(writer.createText(now.toString()));
        });
      });

      return button;
    });
  }
}

In the RTE configuration, this then needs to be added like this:

editor:
  config:
    importModules:
      - { module: '@my-vendor/my-package/timestamp-plugin.js', exports: ['Timestamp'] }
    toolbar:
      items:
        - bold
        - italic
        - '|'
        - clipboard
        - undo
        - redo
        - '|'
        - timestamp