Twenty Seventeen: Warning in Firefox console for scroll-linked positioning effect.

[Shelob9]

When I use TwentySeventeen with Firefox (50.0.2 for Ubuntu) I get this warning on the front page in my console:

This site appears to use a scroll-linked positioning effect. This may not work well with asynchronous panning; see ​https://developer.mozilla.org/docs/Mozilla/Performance/ScrollLinkedEffects for further details and to join the discussion on related tools and features!

Does not happen with TwentySixteen or in Chromium.

#38850 is related as it is about same warning, but is happening in the editor.

[davidakennedy]

Thanks for the report @Shelob9! This is only a warning, so I'm not too worried about it. But we might be able to adjust the JavaScript to avoid the warning and be more performant. It's worth further investigation. Any patch will need to be mindful of the theme's current browser support and not breaking any existing sites.

[ianbelanger]

I just tested this issue in FireFox 73.0.1 and no longer see the error. I am going to close this for now, but it can be reopened if needed.

[ckranebitter]

Hi,

this is still an issue.
If you visit ​http://2017.wordpress.net in Firefox and start to scroll you still get the warning in the console.
The warning is a result because of how the sticky-menu is implemented in Twentyseventeen.
Firefox suggests the »sticky«-css should be used.
So please change the implementation of the menu in upcoming theme-updates to meet Firefox’s best practice suggestion.

Thanks.
Best.
Christoph.

[desrosj]

I just tested this again, and I'm unable to reproduce using Firefox 102.0.1 on MacOS. Additionally, the link included in the ticket description from the original console warning is now a 404, so it seems this has fixed itself.

If this is not the case, please feel free to reopen and include updated information.