itemscope are removed from markup

[torbs]

Describe the bug

When createing a div element with the attribute itemscope, the attribute itemscope is removed from markup and only available as a property. Itemscope as an attrbute is necessary for microdata to work properly. Itemscope is a standard html attribute: https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/itemscope

Reproduction

In repl. Set the attribute itemscope on the h1-element. Inspect the markup and the attribute is removed.

// I stored the element in the variable element
console.log(el.itemscope); // true
console.log(el.getAttribute('itemscope')); // null

We can expand the test to recreate the bug:

assert.ok(div.getAttribute('itemscope'));

Logs

No response

System Info

Chrome Version 111.0.5563.64 (Official Build) (x86_64)
Svelte compiler version 3.57.0

Severity

blocking all usage of svelte

[varl]

We are also seeing different behaviours across Firefox (111.0 (64-bit)) and Chromium (Version 111.0.5563.64 (Official Build) Arch Linux (64-bit)).

Chrome:

inert appears in dom

itemscope does not appear in dom

Firefox

inert does not appear in dom

itemscope does not appear in dom

The AST looks the same in all cases. Not sure if this is a red herring but something noticed during debugging.

[varl]

This works as a workaround (in the repl):

<script>
    import { onMount } from 'svelte'
    import {
        attr,
        element
    } from "svelte/internal";

    let h1 = element('h1')
    let name = 'world';
    onMount(() => attr(h1, 'itemscope', 'true'))
</script>

<h1 bind:this={h1} >Hello {name}!</h1>

Using plain JavaScript to accomplish the same thing also works, but the onMount can be omitted.

[aMediocreDad]

Both of these attributes are set, except as foreign attributes (e.g. itemscope=""), in v3.55.1

This is the specific commit that adds these attributes as boolean_attributes: https://github.com/sveltejs/svelte/pull/7944/files

It seems? Svelte relies on the browser to set these as attributes when the attributes are declared as properties of the element. This could explain the discrepancy between engines with the inert attribute (since it is not supported in FireFox).

Edit: Morning walk cleared it up. Ref: #8414

[Conduitry]

This should be fixed in 3.58.0.