<video> attribute not rendering muted attribute

[dualjack]

Describe the bug

In some scenarios this may be a serious problem, because videos without muted attribute rendered in HTML may fail to autoplay on mobile devices.

Reproduction

https://svelte.dev/playground/017593a95a504a1896498bd79ff82cc2?version=5.45.6

Logs

System Info

Svelte 5.45.6

Severity

annoyance

[brunnerh]

If the element is created client-side, Svelte will set the muted property which is not reflected to the attribute. If the code is rendered via SSR, the attribute should be there.

As far as I know, it really should not matter whether the attribute is there, the property will mute the media. If for some reason this is not the case/autoplay is negatively affected regardless, you could try setting defaultMuted instead, which is reflected to the attribute.

[Conduitry]

See also #6536, including some of the comments there from this year. It does sound like there is some issue that people have been having more recently with this, but I don't know where the line is exactly between the attribute being missing in the browser's DOM representation and the actual behavior of the element.

[dualjack]

I'm just saying that there are some situations (which probably should be fixed in the browser itself) that occur on production sites, and people will keep coming back to this issue.

For now, it is present on iOS 26.

A quick fix is to set the element’s muted attribute manually in another $effect(), which forces the attribute to render.

Thanks for participating. I think this issue can be closed for now, but hey - it would be great if Svelte rendered the muted attribute out of the box, even if it’s a bad or unnecessary practice. It would cost nothing and probably wouldn’t result in another issue report in the future.