Intent to Ship: Rename position-try-options to position-try-fallbacks

[Mason Freed]

{NOTE: this is a replacement of this chromestatus, which has the wrong feature type and cannot be changed.}

Contact emails

mas...@chromium.org, and...@chromium.org

Explainer

None

Specification

https://github.com/w3c/csswg-drafts/issues/10395#issuecomment-2192127524

Summary

The CSSWG resolved to rename this property, because "fallbacks" more accurately describes what this property controls. The word "options" is a bit deceiving, since the styles outside of `position-try` blocks will be tested first, and if they result in a layout that fits within the containing block, none of the "options" will get used. So "fallbacks" is a better word to describe this behavior. https://github.com/w3c/csswg-drafts/issues/10395#issuecomment-2192127524

Blink component

Blink>CSS

TAG review

None

TAG review status

Not applicable

Risks

Interoperability and Compatibility

This is a name change, which will result in the old name no longer functioning. So there is a risk of breakage. However, the anchor positioning feature was very recently shipped, and does not have implementation in other browsers. So we feel the risk is quite small currently, but will grow over time. Given that, we'd like to rename this property ASAP to avoid the risk getting too large. The use counter is currently quite low, around 0.01% in June: https://chromestatus.com/metrics/css/timeline/popularity/784 An HTTP Archive search was performed, which showed that almost all usage comes from one Shopify CSS file (`spec-and-compare.css`), and we intend to reach out to Shopify (or hope for a response from one very special Blink API owner) to make sure this will not break Shopify.

Gecko: No signal

WebKit: No signal

Web developers: No signals

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

None

Debuggability

None

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

Yes

Is this feature fully tested by web-platform-tests?

Yes

https://wpt.fyi/results/css/css-anchor-position

Flag name on chrome://flags

None

Finch feature name

None

Non-finch justification

None

Requires code in //chrome?

False

Tracking bug

https://crbug.com/349600667

Estimated milestones

Shipping on desktop	128
DevTrial on desktop	128

Shipping on Android	128
DevTrial on Android	128

Shipping on WebView

128

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

None

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5090673808900096?gate=5938066895405056

This intent message was generated by Chrome Platform Status.

[Vladimir Levin]

On Wed, Jul 10, 2024 at 6:34 PM Mason Freed <mas...@chromium.org> wrote:

{NOTE: this is a replacement of this chromestatus, which has the wrong feature type and cannot be changed.}

Contact emails

mas...@chromium.org, and...@chromium.org

Explainer

None

Specification

https://github.com/w3c/csswg-drafts/issues/10395#issuecomment-2192127524

Summary

The CSSWG resolved to rename this property, because "fallbacks" more accurately describes what this property controls. The word "options" is a bit deceiving, since the styles outside of `position-try` blocks will be tested first, and if they result in a layout that fits within the containing block, none of the "options" will get used. So "fallbacks" is a better word to describe this behavior. https://github.com/w3c/csswg-drafts/issues/10395#issuecomment-2192127524

Blink component

Blink>CSS

TAG review

None

TAG review status

Not applicable

Risks

Interoperability and Compatibility

This is a name change, which will result in the old name no longer functioning. So there is a risk of breakage. However, the anchor positioning feature was very recently shipped, and does not have implementation in other browsers. So we feel the risk is quite small currently, but will grow over time. Given that, we'd like to rename this property ASAP to avoid the risk getting too large. The use counter is currently quite low, around 0.01% in June: https://chromestatus.com/metrics/css/timeline/popularity/784 An HTTP Archive search was performed, which showed that almost all usage comes from one Shopify CSS file (`spec-and-compare.css`), and we intend to reach out to Shopify (or hope for a response from one very special Blink API owner) to make sure this will not break Shopify.

Have you had a chance to investigate what a breakage looks like by checking the sites using the feature?

I think this rename is fairly safe, but I want to make sure that we're planning on shipping it with a flag that would be able to undo the behavior (a killswitch). I assume having two flags, one to add a new flag and one to remove the old flag is the easiest way to do that. WDYT?

Thanks,

Vlad

 

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[Yoav Weiss (@Shopify)]

On Wed, Jul 17, 2024 at 10:29 PM Vladimir Levin <vmp...@chromium.org> wrote:

On Wed, Jul 10, 2024 at 6:34 PM Mason Freed <mas...@chromium.org> wrote:

{NOTE: this is a replacement of this chromestatus, which has the wrong feature type and cannot be changed.}

Contact emails

mas...@chromium.org, and...@chromium.org

Explainer

None

Specification

https://github.com/w3c/csswg-drafts/issues/10395#issuecomment-2192127524

Summary

The CSSWG resolved to rename this property, because "fallbacks" more accurately describes what this property controls. The word "options" is a bit deceiving, since the styles outside of `position-try` blocks will be tested first, and if they result in a layout that fits within the containing block, none of the "options" will get used. So "fallbacks" is a better word to describe this behavior. https://github.com/w3c/csswg-drafts/issues/10395#issuecomment-2192127524

Blink component

Blink>CSS

TAG review

None

TAG review status

Not applicable

Risks

Interoperability and Compatibility

This is a name change, which will result in the old name no longer functioning. So there is a risk of breakage. However, the anchor positioning feature was very recently shipped, and does not have implementation in other browsers. So we feel the risk is quite small currently, but will grow over time. Given that, we'd like to rename this property ASAP to avoid the risk getting too large. The use counter is currently quite low, around 0.01% in June: https://chromestatus.com/metrics/css/timeline/popularity/784 An HTTP Archive search was performed, which showed that almost all usage comes from one Shopify CSS file (`spec-and-compare.css`), and we intend to reach out to Shopify (or hope for a response from one very special Blink API owner) to make sure this will not break Shopify.

Have you had a chance to investigate what a breakage looks like by checking the sites using the feature?

More specifically, as discussed previously, this usage is coming from a 3P app that merchant sites install and that Shopify has no direct control over. Have you reached out to the app's authors? Have you tried to see if it gets broken by this change?

 

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CADsXd2NGyhFn1y3e_8pr0f8X6emQBK6Kwi_KeatHrN4WN2VA3w%40mail.gmail.com.

[Mason Freed]

On Wed, Jul 17, 2024 at 11:51 PM Yoav Weiss (@Shopify) <yoav...@chromium.org> wrote:

Have you had a chance to investigate what a breakage looks like by checking the sites using the feature?

More specifically, as discussed previously, this usage is coming from a 3P app that merchant sites install and that Shopify has no direct control over. Have you reached out to the app's authors? Have you tried to see if it gets broken by this change? 

So I've been successful in getting in touch with this 3P app author, and they've already disabled their usage of anchor positioning generally. So that specific case should be handled. Generally, the behavior that will be broken by the rename is that fallback positions will not be attempted, meaning only the primary anchor position will be used. 

 

I think this rename is fairly safe, but I want to make sure that we're planning on shipping it with a flag that would be able to undo the behavior (a killswitch). I assume having two flags, one to add a new flag and one to remove the old flag is the easiest way to do that. WDYT?

Thanks, I'm glad you agree that this should be relatively safe, if done soon before usage increases. And to confirm, we do have two flags (CSSPositionTryFallbacks and CSSPositionTryOptions) which work exactly as you suggest. We will flip flop their states, but retain the ability to swap that back via Finch in case of emergency.

Thanks,

Mason

[Daniel Bratell]

LGTM1

/Daniel

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDjLeUUVCMdxfTswk0vVj2QAiqECsAaT%2B_kCGieiDsbxZA%40mail.gmail.com.

[Chris Harrelson]

LGTM2

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/dfba05ae-c307-41a5-856d-26aa2840baa2%40gmail.com.

[Mike Taylor]

LGTM3

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw8K_3bxNH_9%3Dykb_wqWTwZjniCPKWfGBiPqtYxNg6h6fg%40mail.gmail.com.

[Mason Freed]

Thanks all!