`select` with reactive `disabled` attribute hides the binded `value`

[ivenuss]

Describe the bug

Might relate to: #16017.

After upgrading to 5.33.5 select with disabled state behaves unexpectedly.

When setting disabled attribute to select component (just a wrapper around select element), then the binded value suddenly disappears.

While reproducing the issue I figured out few things:

• select has to be in separated file as component to reproduce it
• if you remove the bind bind:value and change it to value={value} inside select component, it works
• when I remove disabled prop from select component, it works

Reproduction

Broken >= 5.33.5

https://svelte.dev/playground/6d9f0dbfa2c74e8f88483dd90d0abfd6?version=5.33.7

Working < 5.33.5

https://svelte.dev/playground/6d9f0dbfa2c74e8f88483dd90d0abfd6?version=5.33.4

System Info

"svelte": "^5.33.7",
"@sveltejs/kit": "^2.21.1"

Severity

blocking an upgrade

[sorinpopescu]

Hi.
I can confirm.
Happen only with "disabled".

[paoloricciuti]

Mmm it's weird that my PR broke this as this is a reactivity issue and I only touched the server code

[paoloricciuti]

Oh yeah I suppose the culprit was actually #15961

[sorinpopescu]

When you render the pages with let userData = $state( ... and at some point you update the values, but the change is not reflected, instead it gets to empty no selected value.

This works
<Select id="currency" items={listCurrencies} bind:value={userData.currency} aria-label={translation?.profile?.currency ?? 'Currency'} placeholder={translation?.profile?.currency ?? 'Currency'} required underline={true} class={classInputField} />

this do not work

<Select id="currency" items={listCurrencies} bind:value={userData.currency} aria-label={translation?.profile?.currency ?? 'Currency'} placeholder={translation?.profile?.currency ?? 'Currency'} required underline={true} disabled={isLoading} class={classInputField} />

Thanks

[paoloricciuti]

This two snippets are the same 😄 Btw i think i found the bug

[sorinpopescu]

Are not the same:
the first one that works do not have "disabled={isLoading}"
the second has that "disabled={isLoading}"

Looks like working in 5.33.8.

Thanks