Contact emails [email protected], [email protected]
Explainer This feature: <https://chromestatus.com/admin/features/launch/5355965538893824/This%20feature:%20https://github.com/jeremyroman/alternate-loading-modes/blob/main/same-origin-explainer.md> https://github.com/WICG/nav-speculation/blob/main/same-origin-explainer.md This trial: https://github.com/WICG/nav-speculation/blob/main/same-origin-chrome-origin-trial.md Larger project: <https://chromestatus.com/admin/features/launch/5355965538893824/Larger%20project:%20https://github.com/jeremyroman/alternate-loading-modes/blob/main/README.md> https://github.com/WICG/nav-speculation/blob/main/README.md Specification https://wicg.github.io/nav-speculation/prerendering.html Design docs https://docs.google.com/document/d/1P2VKCLpmnNm_cRAjUeE-bqLL0bslL_zKqiNeCzNom_w/edit?usp=sharing Summary Prerendering loads a web page before it is needed, so that when the actual navigation to that page occurs, it can be shown instantly. This experiment is for the specific case of same-origin prerendering triggered by the Speculation Rules API. An earlier, related experiment supported prefetching <https://groups.google.com/a/chromium.org/g/blink-dev/c/Cw-hOjT47qI/m/EObn9-4MAgAJ> using this API. This is a separate experiment that requires its own origin trial token. This experiment has some limitations. See the explainer <https://github.com/WICG/nav-speculation/blob/main/same-origin-chrome-origin-trial.md#speculation-rules> for details. Blink component Internals>Preload>Prerender <https://bugs.chromium.org/p/chromium/issues/list?q=component:Internals%3EPreload%3EPrerender> TAG review https://github.com/w3ctag/design-reviews/issues/667 TAG review status Pending Risks Interoperability and Compatibility Interoperability risk: We believe that some browsers already have prerendering implementations which are not well-specified and may differ from each other. Our vision is to produce a specification that can help improve interoperability. There is a risk that other browsers do not converge on a prerendering standard. The danger here is that different browsers have different ways to trigger a prerendered page, and prerendered pages behave differently in different browsers. Prerendering is a web-visible behavior, since it involves fetching the page and executing its scripts. Prerendering can depend on UA-specific heuristics. For example, the browser might decide to act on a hint to prerender based on the system load, and the presence of other prerenders. We do not intend to codify heuristics in the specification. A conforming browser might simply ignore all hints to prerender a page. Compatibility risk: Some use cases will need to know whether a page is being prerendered. Ads and analytics are likely examples of this. This feature exposes `document.prerendering` to detect prerendering, but there is a risk of sites that would benefit from using the API, not using it. We believe that this risk is tractable because prerendering has existed in Chrome in the recent past and currently exists in some other browsers. We also intend to add a header to network requests like `Purpose: prefetch` so that origin servers can identify requests for prerendered pages. Gecko: No signal WebKit: No signals, while Safari appears to have some form of prerendering already. Web developers: No signals Other signals: No signals Ergonomics This feature is triggered by the Speculation Rules API: https://chromestatus.com/feature/5740655424831488 Activation Developers can use the Speculation Rules API to use the feature. The feature should just work for most existing pages. Developers should be aware of restrictions on prerendering content (they cannot play audio or perform other disruptive behavior, etc). This feature would benefit from good documentation. Security This feature is the first use of the Multiple-Page Architecture, which is a significant change to Chromium's internals. Both MPArch and this feature in particular underwent significant security review. See the design doc for more details. >From a web-exposed perspective, the security and privacy concerns are smaller, because this feature is restricted to the same-origin case only. Goals for experimentation To evaluate how the prerendering feature works on real sites before shipping it by default. This is a large feature and it's risky to ship without trying it first on real sites. We will be evaluating performance, stability, and correctness, and any other feedback the sites have when they use this feature. Reason this experiment is being extended The sites participating in this trial need more time to set up their services with the feature. We would like to collect more data from them for evaluating the feature. Ongoing technical constraints None Debuggability Currently DevTools does not work for prerendered pages. On activation, DevTools must be closed and reopened in order to inspect the page. We have plans to add DevTools support for prerendering. A meta bug for this work is at https://crbug.com/1217029. As a very small support, prerendered pages are visible in chrome://process-internals. Also final results of prerendering are shown in chrome://histograms. Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)? No This feature is only supported on Android at first. As the feature is a cross-cutting one, where almost all of Chrome's features must be potentially taught about prerendered pages, we are starting with a single platform and expanding later. Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/master/docs/testing/web_platform_tests.md> ? Partially tested. We’re now upstreaming wpt_internals/ tests (document <https://docs.google.com/document/d/1XqdlrYdPbLLEfJfjQE1IK0I5Elj_2uiGaK5aUGYc1CU/edit?usp=sharing> ). Flag name Prerender2 Requires code in //chrome? False Tracking bug https://crbug.com/1126305 Launch bug https://crbug.com/1167987 Estimated milestones Previous experiment timeline: M94 to M98 Requested extension timeline: M99 to M103 Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5355965538893824 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 on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CABj5diM0QEn5hBg1r80PWFw6qpXhCVmC05p0qh5KT5h9xKh19Q%40mail.gmail.com.
