Intent to Extend Experiment: Soft Navigation Heuristics

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Ian Clelland

Jan 22, 2024, 4:01:14 PMJan 22
to blink-dev

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Exposes the (experimental) soft navigation heuristics [1] to web developers, using both PerformanceObserver and the performance timeline. [1]

Blink component


TAG review

TAG review status

Issues addressed

Chromium Trial Name


Link to origin trial feedback summary

Origin Trial documentation link


Interoperability and Compatibility


Gecko: No signal (

WebKit: No signal (

Web developers: Strongly positive

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?


Goals for experimentation

Reason this experiment is being extended

We are still collecting feedback from partners, who are evaluating the suitability of this API to replace existing ad-hoc methods of measuring soft navigations, including some who were only recently able to start experimenting. Additionally, we have made changes to the heuristics, in response to testing and feedback, to eliminate some false-positive detections, and better match the behaviour of real-world single-page apps. Some of these changes initially went out in Chrome 120, and were refined in Chrome 121; some will be released with Chrome 122. We'd like to give developers a chance to experiment with these changes, to help inform any future adjustments that need to be made. After Chrome 123, we intend to pause the experiment while we act on all of the feedback, and decide whether further changes to the heuristics are necessary, or if the API is in good enough shape to consider shipping.

Ongoing technical constraints




Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?


Is this feature fully tested by web-platform-tests?


Flag name on chrome://flags


Finch feature name


Requires code in //chrome?


Tracking bug

Estimated milestones

OriginTrial desktop last123
OriginTrial desktop first117
OriginTrial Android last123
OriginTrial Android first117
OriginTrial webView last123
OriginTrial webView first117

Link to entry on the Chrome Platform Status

Links to previous Intent discussions

Intent to prototype: Intent to Experiment:
Intent to Extend Experiment:
Intent to Ship:

This intent message was generated by Chrome Platform Status.

Mike Taylor

Jan 23, 2024, 3:15:42 PMJan 23
to Ian Clelland, blink-dev

LGTM to extend to 123 inclusive.

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