Pluto: include init DOM in every display

[fonsp]

Currently, the init DOM (the return value of setup_connection(session::Session{PlutoConnection})) is only included in the first HTML output generated by JSServe displaying in app.

This causes an issue when reloading: if you run this code in Pluto, then the app is interactive:

import JSServe.TailwindDashboard as D

app2 = App() do
    numberinput = D.NumberInput(0.0)
    slider = D.Slider("Test", 1:5)
    checkbox = D.Checkbox("check this", true)
    dropdown = D.Dropdown("chose", ["option 1", "option 2", "option 3"])

    return DOM.div(
		numberinput,
		dropdown,
		slider,
		(JSServe.Observables.@map &(slider.value) + &(numberinput.value)),
		checkbox,
    )
end

But if you then re-run the same cell and refresh your browser, it not longer works, because the init DOM is nowhere on the page.

The easy solution is to include this init DOM on every app HTML render in Pluto. This means that it does not depend on whether-it-has-been-rendered-before, and the <script type="module" src="..."> is guaranteed to run only once if included multiple times with the same src (also outside of Pluto).

Also: I was prototyping a new Connection type that uses fonsp/Pluto.jl#2726, and found the limitation that I need to include some init DOM for every app render, not just the first one. (I was hoping that SubConnection has the parent connection type as parameter. Then I could define setup_connection(session::Session{SubConnection{PlutoConnection}}).)

[SimonDanisch]

Refreshing the browser is a bit more complicated than this, since the html/js on the page will get out of sync with the state in the Session.
I included a workaround for refreshing for VSCode here: #190
Which requires to re-rendering the App completely.

[fonsp]

Alright, I'll leave that up to you, but what do you think about my last paragraph? It would be nice to have API to give an init DOM that is rendered for subconnections.

[SimonDanisch]

Hm, I'd like to avoid it - does this actually need to be for the subconnection or could we do anything in the main connection?
I need to think about this, what exactly do you need in there? Just what gets into init usually?