I think the author is referring to immediate mode because of

UI=f(state)

I do understand that's what they have in mind. But that's not what immediate mode means. Function application is not the only criteria.

We are talking about rendering into a browser by twiddling DOM APIs. That's definitely retained mode rendering and repeatedly claiming it's immediate mode doesn't make it true

	▲	magicalhippo a day ago \| parent \| next [-]
		If you compare the code using the presented framework to code using say immediate mode library like ImGui[1][2] for example, the presented framework does indeed seem to be exposing a retained mode API. [1]: https://pthom.github.io/imgui_explorer/ [2]: https://github.com/ocornut/imgui
	▲	account42 a day ago \| parent \| prev [-]
		With that argument, every UI is retained mode because everything gets saved in the GPU's scan out buffer.