Can you comment on the progress made towards shipping since the last experiment extension?
On Wed, Oct 7, 2026 at 4:27 AM Chromestatus <[email protected]> wrote: > *Contact emails* > [email protected], [email protected] > > *Explainer* > https://github.com/WICG/nav-speculation/blob/main/prerender-until-script.md > > *Specification* > > https://wicg.github.io/nav-speculation/prerendering.html#speculation-rule-set-prerender_until_script-rules > > *Design docs* > > > https://docs.google.com/document/d/18Ny-OJ5kfyxkZ8h73OGigk8B3gDnoxjH34RVcvSo5Do/edit?tab=t.szm4nrdsfrjv > > *Summary* > This extends speculation rules to introduce a new action called > prerender_until_script. It is designed as an intermediate option between > the existing prefetch (which only fetches the main document) and prerender > (which fully renders the page and runs all scripts). This new action will > fetch and parse a page, discover and download its subresources like images > and stylesheets, but will pause all script execution. When the user > navigates to the page, it activates, and all the deferred scripts are then > executed in order. This allows for a near-instant page load for > content-heavy sites without the performance cost or side effects of running > analytics or third-party scripts prematurely. > > *Blink component* > Internals>Preload>Prerender > <https://issues.chromium.org/issues?q=customfield1222907:%22Internals%3EPreload%3EPrerender%22> > > *Web Feature ID* > speculation-rules <https://webstatus.dev/features/speculation-rules> > > *Search tags* > speculationrules <http:///features#tags:speculationrules>, prerendering > <http:///features#tags:prerendering>, prefetch > <http:///features#tags:prefetch>, nostateprefetch > <http:///features#tags:nostateprefetch> > > *TAG review* > https://github.com/w3ctag/design-reviews/issues/1183 > > *TAG review status* > Not applicable > > *Origin Trial Name* > PrerenderUntilScript > > *Goals for experimentation* > - whether this feature work as expected on developers' sites. - whether it > is safe to leave inline event handlers as it is on websites. Developers > will be able to monitor the error rate of JavaScript execution, and provide > feedback on that. > > *Chromium Trial Name* > PrerenderUntilScript > > *Origin Trial documentation link* > https://github.com/WICG/nav-speculation/blob/main/prerender-until-script.md > > *WebFeature UseCounter name* > kSpeculationRulesPrerenderUntilScript > > *Risks* > > > *Interoperability and Compatibility* > Other browsers do not implement this feature yet, but if should be safe > because: 1. it is an optimization, so it should be no-op on other browsers > 2. other browsers do not implement any of speculationrule actions yet. > > *Gecko*: No signal > > *WebKit*: No signal > > *Web developers*: Positive ( > https://github.com/WICG/nav-speculation/issues/305) Web developers > proposed that UA should implement an intermediate option between the > existing prefetch and prerender actions. > > *Other signals*: > > *Ergonomics* > no > > *Activation* > No. Developers should be able to easily try this feature by changing > "prerender" to "prerender_until_script" following the explainer. > > *Security* > It should be as safe as prerender action, as it pauses JavaScript > execution during prerendering. One potential risk is the inline event > handlers. inline event handlers will be executed normally during > prerendering, it seems risky but we find websites usually put inline > scripts before defining a inline event handler, and the inline script will > make the parser be paused, therefore user agent has no chance to execute > the inline event handlers. So, we think is is a low possibility risk, and > would like to confirm with Origin Trial. > > *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? > *No information provided* > > > *Reason this experiment is being extended* > 1. Developers have reported that it is currently slower than prefetch. We > suspect one of the reasons is that the Prerender2FallbackPrefetchSpecRules > feature is not yet enabled by default. Since this feature is launching > soon, we'd like to monitor our metrics once it goes live to see if > performance improves. 2. Some developers says that they do not have enough > bandwidth to work on it and they're moving slowly, so we'd like to extend > the OT to wait for their feedback. > > *Reason this experiment is being extended* > We realized there might be a performance issue, and since the optimization > is included in M154, we would like to extend the OT to allow partners to > re-try this. > > *Ongoing technical constraints* > We assume it is ok not to handle inline event handlers differently as for > now most pages put <script> tag before inline event handlers. But if it > happens, we need to refine the inline event handlers' execution logic. > > *Debuggability* > As well as other speculationrule features, this feature shows its current > status on devtools. > > *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 > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* > Yes > > > *Flag name on about://flags* > prerender-until-script > > *Finch feature name* > PrerenderUntilScript > > *Requires code in //chrome?* > False > > *Tracking bug* > https://issues.chromium.org/u/1/issues/428500219 > > *Measurement* > Blink.UseCounter.Features > > *Estimated milestones* > Origin trial desktop first 144 > Origin trial desktop last 150 > Origin trial extension 1 end milestone 154 > Origin trial extension 2 end milestone 159 > DevTrial on desktop 144 > Origin trial Android first 144 > Origin trial Android last 150 > DevTrial on Android 144 > Origin trial WebView first 144 > Origin trial WebView last 150 > > *Link to entry on the Chrome Platform Status* > https://chromestatus.com/feature/6324676351623168?gate=5423768481693696 > > *Links to previous Intent discussions* > Intent to Prototype: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68f20f78.050a0220.29f70d.004e.GAE%40google.com > Intent to Experiment: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6965e5e2.050a0220.22847.035a.GAE%40google.com > Intent to Extend Experiment 1: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6a1e652b.c5ff9f8d.331a2d.02bd.GAE%40google.com > > > 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 [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6ac5ae1d.a448aa95.130ec9.016d.GAE%40google.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6ac5ae1d.a448aa95.130ec9.016d.GAE%40google.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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