why diffProp function gets most recent property value on "value" update?

[srghma]

here

purescript-halogen-vdom/src/Halogen/VDom/DOM/Prop.purs

Lines 149 to 155 in 8b91e55

	_, "value" → do
	let elVal = Fn.runFn2 unsafeGetProperty "value" el
	if Fn.runFn2 Util.refEq elVal val2
	then pure v2
	else do
	EFn.runEffectFn3 setProperty prop2 val2 el
	pure v2

well, I kind of understand why, but still want to know the explanation

the other question is should we update other propNames this way?

for example react calls value, checked, selected the Controlled attributes and handles them differently (diffHydratedProperties)

[natefaubion]

In many browsers, though it may not be the case anymore, setting the input value always resets the cursor position/selection. This avoids setting it if it has not changed so as not to reset the cursor when you are typing. It's a common bit of virtual DOM "lore".

https://github.com/elm/virtual-dom/blob/5a5bcf48720bc7d53461b3cd42a9f19f119c5503/src/Elm/Kernel/VirtualDom.js#L496
https://github.com/snabbdom/snabbdom/blob/ffc166cdb4beae1c800ce2132821baea1c547d6f/src/modules/props.ts#L27

[srghma]

snabbdom does this only for value, elm does this for value and checked

why elm does this for checked too?

[natefaubion]

I don't know the answer to that. I've never had issues with checked. You could maybe follow the blame for that code.

[srghma]

it comes from this https://github.com/elm/virtual-dom/issues/117 issue

notice the checked False in this example https://ellie-app.com/qzwpBK5xxMa1

I dont know if this happens in halogen too