Ready for Developer Testing: Container Timing

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7:04 AM (3 hours ago) 7:04 AM

to blin...@chromium.org, jda...@igalia.com, jwilli...@bloomberg.net, mmo...@google.com, shas...@google.com

Contact emails

jwilli...@bloomberg.net

Explainer

https://github.com/bloomberg/container-timing

Specification

https://bloomberg.github.io/container-timing

Design docs

https://github.com/bloomberg/container-timing

Summary

The Container Timing API enables monitoring when annotated sections of the DOM are displayed on screen and have finished their initial paint. A developer will have the ability to mark subsections of the DOM with the containertiming attribute (similar to elementtiming for the Element Timing API) and receive performance entries when that section has been painted for the first time. This API will allow developers to measure the timing of various components in their pages.

Blink component

Blink>PerformanceAPIs

Web Feature ID

No information provided

Search tags

performance, container, timing

Risks

Interoperability and Compatibility

Interoperability is good. We have positive signals, and an implementation from Mozilla in Firefox.

Gecko: Positive (https://github.com/mozilla/standards-positions/issues/1155) Firefox are positive and are working on an implementation: https://phabricator.services.mozilla.com/D279373

WebKit: Neutral (https://github.com/WebKit/standards-positions/issues/442)

Web developers: No signals

Other signals:

Ergonomics

Performance overhead only happens when enabling, any overhead is low because we piggy back on DOM-traversals which are already happening.

Activation

The feature is consistent with other Performance APIs that work on the Performance Timeline. This feature can't be polyfilled properly, there has been an attempt (see Explainer) but that has high resource usage. Today all the documentation lives in the explainer, we will hope to promote this more once it is exposed to the wider development community.

Security

https://github.com/bloomberg/container-timing/?tab=readme-ov-file#security-and-privacy

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

Debuggability

Container Timing entries can be printed to the developer console from the PerformanceObserver. The attributes are also observable in the Elements Panel. This feature has basic support from DevTools.

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

Yes
This feature is implemented in Blink and isn't subject to any platform specific APIs

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

Yes
https://wpt.fyi/results/container-timing/tentative?label=experimental&label=master&aligned

DevTrial instructions

https://github.com/bloomberg/container-timing?tab=readme-ov-file#chrome-canary-and-chrome-beta

Flag name on about://flags

enable-experimental-web-platform-features

Finch feature name

ContainerTiming

Requires code in //chrome?

False