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? > > > 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. 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