Intent to Experiment: Speculation rules: target_hint field

[Chromestatus]

Contact emails

nhi...@chromium.org, robe...@chromium.org

Explainer

https://github.com/WICG/nav-speculation/blob/main/triggers.md#window-name-targeting-hints

Specification

https://wicg.github.io/nav-speculation/speculation-rules.html

Summary

This extends speculation rules syntax to allow developers to specify the target_hint field. This field provides a hint to indicate a target navigable where a prerendered page will eventually be activated. For example, when _blank is specified as a hint, a prerendered page can be activated for a navigable opened by window.open(). The field has no effect on prefetching. The specification allows this field to accept any strings that are valid as navigable target name or keyword as the value, but this launch supports only one of "_self" or "_blank" strings. If the hint is not specified, it's treated like "_self" is specified.

Blink component

Internals>Preload>Prerender

Search tags

speculationrules, prerendering

TAG review

https://github.com/w3ctag/design-reviews/issues/931

TAG review status

Issues addressed

Risks

Interoperability and Compatibility

None

Gecko: Neutral (https://github.com/mozilla/standards-positions/issues/620)

WebKit: No signal (https://github.com/WebKit/standards-positions/issues/54)

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

Goals for experimentation

Ongoing technical constraints

None

Debuggability

DevTools supports speculation rules: https://developer.chrome.com/blog/debugging-speculation-rules/

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

No

Android WebView doesn't support speculation rules yet.

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

Yes

https://wpt.fyi/results/speculation-rules/prerender

Flag name on about://flags

enable-speculation-rules-prerendering-target-hint

Finch feature name

Prerender2InNewTab

Requires code in //chrome?

False

Tracking bug

https://issues.chromium.org/issues/40234240

Estimated milestones

Origin trial desktop first	135
Origin trial desktop last	140
Origin trial Android first	135
Origin trial Android last	140

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5162540351094784?gate=5081681619058688

This intent message was generated by Chrome Platform Status.

[Huanpo Lin]

The previous email didn't include the section of Goals for experimentation.

I'm sending this email as a follow-up.

Goals for experimentation

To evaluate how the prerendering target_hint support works on real sites before shipping it by default. We will be evaluating performance, stability, and correctness, and any other feedback the sites have when they use this feature.

Kind regards

[Alex Russell]

LGTM1

I continue to be concerned that we are proliferating these declarative forms without any object model. I'd like to see an OM for speculation rules, import maps, and other similar designs. Has this come up in your discussions with the TAG?

Best,

Alex

[Chris Harrelson]

(BTW, for the intent owner: only one LGTM needed for this intent.)

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[Domenic Denicola]

Thank you!

On Thu, Mar 13, 2025 at 1:50 AM Alex Russell <sligh...@chromium.org> wrote:

LGTM1

I continue to be concerned that we are proliferating these declarative forms without any object model. I'd like to see an OM for speculation rules, import maps, and other similar designs. Has this come up in your discussions with the TAG?

As with all previous times you've replied to speculation rules features with this feedback, we invite you to give it through standards forums, especially if you have partners for whom such additions would make a difference, or concrete use cases that cannot be accomplished with the current design.

And no, the TAG has not expressed similar feedback; indeed, their feedback has pushed toward making things more declarative.

 

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