Having written a wysiwyg editor myself, the bulk of the work in such a project doesn't really touch on what jQuery does.
Assuming you're using contenteditable, a lot of it is about resolving cross-browser differences in the implementation. Probably also reimplementing most of the execCommands since they're wildly inconsistent -- which does involve some DOM manipulation, but is more about using the selection API.
Assuming you're using contenteditable, a lot of it is about resolving cross-browser differences in the implementation. Probably also reimplementing most of the execCommands since they're wildly inconsistent -- which does involve some DOM manipulation, but is more about using the selection API.