This is huge, thanks for improving Speculation Rules moderate behaviour! On Tue, Jun 24, 2025 at 2:51 AM Domenic Denicola <dome...@chromium.org> wrote:
> > > On Mon, Jun 23, 2025 at 5:59 PM Yoav Weiss (@Shopify) < > yoavwe...@chromium.org> wrote: > >> Thanks for improving "moderate"! >> >> On Mon, Jun 23, 2025 at 10:54 AM 'Domenic Denicola' via blink-dev < >> blink-dev@chromium.org> wrote: >> >>> Contact emailsnhir...@chromium.org >>> >>> Specification >>> https://wicg.github.io/nav-speculation/speculation-rules.html#:~:text=early%20as%20possible.-,%22moderate%22,balance%20between%20%22eager%22%20and%20%22conservative%22.,-%22conservative%22 >>> >>> Summary >>> >>> On mobile, "moderate" eagerness speculation rules prefetches and >>> prerenders now trigger when a link enters the viewport and passes other >>> conditions that indicate that it's more likely to be clicked. The previous >>> behavior, of waiting until pointerdown, was the same as "conservative" >>> eagerness. This new behavior is more useful as it better reflects author >>> intent to be more eager than the "conservative" setting. More detail on >>> this and other upcoming improvements to speculation rules eagerness are >>> available at >>> https://docs.google.com/document/d/1YPbtUPfZIDElzBZNx8IQMzRFvy8oauLG_i1XIr6jgTs/edit?usp=sharing >>> . >>> >> >> Are you planning to ship the "simple viewport heuristics", the "complex >> viewport heuristics", or both? >> > > This PSA is for "complex viewport heuristics", the new "moderate" behavior. > > Future PSAs will be used for "eager" (which is "simple viewport > heuristics" on mobile.) > > >> >> >>> >>> >>> Blink componentInternals>Preload >>> <https://issues.chromium.org/issues?q=customfield1222907:%22Internals%3EPreload%22> >>> >>> Risks >>> >>> >>> Interoperability and Compatibility >>> >>> The exact definitions of eagerness levels are left vague in the >>> specification. ("User agents should enact the candidate if user behavior >>> suggests the user may navigate to this URL in the near future. For >>> instance, the user might have scrolled a link into the viewport and moved >>> the cursor over it for some time.") This change is in line with those >>> suggestions. Due to speculation rules' nature as a progressive enhancement, >>> it is very hard to depend on the exact heuristic, so varying across browser >>> engines, platforms, and browser versions should not pose significant >>> interoperability or compatibility risks. As evidence, the heuristic has >>> varied across mobile and desktop ever since launch, and this has not caused >>> such problems. >>> >>> >>> *Gecko*: Neutral ( >>> https://github.com/mozilla/standards-positions/issues/620#issuecomment-2546739520) >>> We have not asked Firefox for their thoughts on this specific change. They >>> are positive on and implementing prefetching, and will likely make their >>> own choices for how to implement each eagerness level. >>> >>> *WebKit*: No signal ( >>> https://github.com/WebKit/standards-positions/issues/54) We've not >>> asked Safari for their thoughts on this specific change. They have recently >>> indicated a tentative positive position towards conservative-eagerness >>> prefetching. >>> >>> *Web developers*: Positive We've seen several developers re-create this >>> viewport-based technique using JavaScript to manually insert and remove >>> speculation rules, e.g. in the Quicklink library. >>> >>> *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 >>> >>> We have unfortunately not yet made this feature work in DevTools mobile >>> emulation mode. That work is tracked in >>> https://issues.chromium.org/issues/420724833 and will be worked on as a >>> follow up. >>> >>> Will this feature be supported on all six Blink platforms (Windows, Mac, >>> Linux, ChromeOS, Android, and Android WebView)?No >>> >>> This is only applicable to Android, and speculation rules are not yet >>> supported on Android WebView. >>> >>> Is this feature fully tested by web-platform-tests >>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> >>> ?No >>> >>> Because the specification intentionally allows user agent flexibility, >>> web platform tests do not capture any specific heuristic here. >>> >>> Flag name on about://flagsNone >>> >>> Finch feature namePreloadingViewportHeuristics >>> >>> Rollout plan(RARE) Experiment users ramp up over time >>> >>> Tracking bughttps://issues.chromium.org/issues/372053392 >>> >>> Estimated milestones >>> Shipping on Android 138 >>> Link to entry on the Chrome Platform Status >>> https://chromestatus.com/feature/5079361929347072?gate=5206542386987008 >>> >>> This intent message was generated by Chrome Platform Status >>> <https://chromestatus.com/>. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "blink-dev" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to blink-dev+unsubscr...@chromium.org. >>> To view this discussion visit >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra-Y5%3DEZ1yUWA8qg152%2BLz5q_jPTUKMMfg866BvO9DgCZg%40mail.gmail.com >>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra-Y5%3DEZ1yUWA8qg152%2BLz5q_jPTUKMMfg866BvO9DgCZg%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to blink-dev+unsubscr...@chromium.org. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra_UEAQkEm5y6e_ZureO_U8kew8vtdN5839uiRKcXQcTmw%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra_UEAQkEm5y6e_ZureO_U8kew8vtdN5839uiRKcXQcTmw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- gTech Up Gilberto Cocchi Web Ecosystem Consultant gilber...@google.com Google Italy | Via Federico Confalonieri 4 | Porta Nuova Isola | Building C | Milan 20124 Registered in Milan, Italy This email may be confidential and privileged. 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