Allow extra/custom content
In CKE 4 the following extra content rules were defined:
extraAllowedContent : 'iframe(*)[*]{*}; img(*)[*]{*}; script(*)[*]{*}; ins(*)[*]{*}',
see: https://dev.quiqqer.com/quiqqer/ckeditor4/blob/dev/bin/Editor.js#L259-259
When using these rules, iframes, imgs, scripts and ins elements aren't purged automatically by the editor.
In CKE5 e.g. iframes are automatically removed from the content.
Therefore it's necessary to allow this extra content again.
This could (probably) be done by a custom plugin following this guide: https://ckeditor.com/docs/ckeditor5/latest/framework/guides/deep-dive/conversion/conversion-preserving-custom-content.html
Content that works in CKE5:
-
iframe -
img -
script -
ins
Edited by Jan Wennrich