disabled=true property toggles on every event

[pizzathemeguy]

When an element has the attribute attribute.disabled(True) it toggles between disabled and enabled on every event. I suspect this will happen with all the as_property attributes, but I've not tested anything other than disabled.

e.g. In this example every time the "raise event" button is pressed the "I should always be disabled" button toggles between disabled/enabled.

import lustre
import lustre/attribute
import lustre/effect
import lustre/element
import lustre/element/html
import lustre/event

pub type Model =
  Nil

fn init(_flags) -> #(Model, effect.Effect(Msg)) {
  #(Nil, effect.none())
}

pub type Msg {
  UserPressedButton
}

fn update(model: Model, msg: Msg) -> #(Model, effect.Effect(Msg)) {
  case msg {
    UserPressedButton -> {
      #(model, effect.none())
    }
  }
}

pub fn view(_model: Model) -> element.Element(Msg) {
  html.div([], [
    html.button([event.on_click(UserPressedButton)], [
      element.text("raise event"),
    ]),
    html.div([], [
      html.button([attribute.disabled(True)], [
        element.text("I should always be disabled"),
      ]),
    ]),
  ])
}

pub fn main() {
  let app = lustre.application(init, update, view)

  let assert Ok(_) = lustre.start(app, "#app", Nil)
  Nil
}

from what I could tell was happening in vdom.ffi.mjs createElementNode():

1. attr.as_property on line 235 is true
2. the call to if (canMorph) prevAttributes.delete(name); that happens for as_property=False attributes is not called
3. on line 303 the attribute gets removed with el.removeAttribute(attr);

I didn't have a chance to dig into the code more to see if adding if (canMorph) prevAttributes.delete(name); to the as_property=True condition would have other downstream effects, but that at the very least fixed the toggling button I was seeing.

[hayleigh-dot-dev]

Ah thank you for investigating this. I think this might be a regression: I'll take a look :)

[hayleigh-dot-dev]

Hey there I think I've fixed this, could you give 4.2.2 a try and see if the issue is resolved?

[pizzathemeguy]

Gave 4.2.2 a try in the example I posted as well as the project I originally noticed the behavior in; both looked good. Appreciate it, thank you!