Intent to Prototype: No-Vary-Search support for prerender
Liviu Tinta
Contact emails
dom...@chromium.org, jbr...@chromium.org, liviu...@chromium.org
Explainer
https://github.com/WICG/nav-speculation/blob/main/no-vary-search.md#prerendering-activation
Specification
None
Summary
Enables a prerender entry to match even if URL query parameters change. The No-Vary-Search HTTP response header declares that some or all parts of a URL's query can be ignored for cache matching purposes. It can declare that the order of query parameter keys should not cause cache misses, that specific query parameters should not cause cache misses or that only certain known query parameters should cause cache misses. It could apply to multiple caches, but this entry refers to support for prerender.
Blink component
Motivation
Caching is useful for making web pages load faster, and thus creating better user experiences.
One of the most important cache keys for web resources is the resource's URL. However, sometimes multiple URLs can represent the same resource. This leads to caches not always being as helpful as they could be: if the browser has the resource cached under one URL, but the resource is then requested under another, the cached version will be ignored.
Via a new HTTP header, No-Vary-Search, resources can declare that some or all parts of the query can be ignored for cache matching purposes.
This feature is focused on adding support for No-Vary-Search header to the prerender cache.
Initial public proposal
https://github.com/WICG/nav-speculation/blob/main/no-vary-search.md#prerendering-activation
TAG review
https://github.com/w3ctag/design-reviews/issues/797
TAG review status
Closed (validated).
Risks
Interoperability and Compatibility
None
Gecko: No signal
WebKit: No signal
Web developers: No signals
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
Yes. The prerender will be available in DevTools->Application->Speculative loads->Speculations and the DevTools->Application->Speculative loads specifies the Speculative loading status for the current page. A developer could test that No-Vary-Search header functionality is working in Dev Tools using the information on the two screens mentioned above.
Is this feature fully tested by web-platform-tests?
Yes, Web Platform Tests will be added.
Flag name on chrome://flags
None
Finch feature name
None
Non-finch justification
None
Requires code in //chrome?
False
Tracking bug
https://issues.chromium.org/issues/41494389
Estimated milestones
No milestones specified