LGTM to extend experimentation until M154 inclusive (I believe this corresponds to a 3 months extension with us moving to 2 week cadence half way through)
On Tuesday, June 2, 2026 at 7:08:09 AM UTC+2 Chromestatus 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-OJ5kfyxkZ8h73OGigk8B3gDnoxjH34 RVcvSo5Do/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. With my developer hat on, looking forward to that! :) 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. *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 first144 Origin trial desktop last150 Origin trial extension 1 end milestone154 DevTrial on desktop144 Origin trial Android first144 Origin trial Android last150 DevTrial on Android144 Origin trial WebView first144 Origin trial WebView last150 *Link to entry on the Chrome Platform Status* https://chromestatus.com/feature/6324676351623168?gate=5317079747133440 *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 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/b82d624f-33ec-4dc5-8cea-5c39fa325fc8n%40chromium.org.
