It surely does, because it's a crucial feature for a text editor, but the developers had to implement and undo/redo stack in their lib. Anyway this approach is

It surely does, because it's a crucial feature for a text editor, but the developers had to implement and undo/redo stack in their lib. Anyway this approach is the only good one if you don't want to produce crappy HTML that will end up on your site. TinyMCE and the rest are obsolete, and editors like DraftJS or mobiledoc-kit are the only viable solutions until browsers offer a new, not broken alternative to content-editable.