Intent to Ship: Methods that change Array and TypedArray by copy

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Shu-yu Guo

Nov 8, 2022, 3:32:34 PM11/8/22
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Provides additional methods on Array.prototype and TypedArray.prototype to enable changes on the array by returning a new copy of it with the change.

Blink component


TAG review

TC39 proposal that only touches Array.prototype, without other interactions with web APIs.

TAG review status

Not applicable


Interoperability and Compatibility

No interoperability risk as this is a TC39 proposal implemented in tandem by browser engines. Minimal but non-zero web compatibility risk. Any new methods on Array.prototype carries with it a web compat risk as many JS libraries add their own methods to Array.prototype, and sometimes those libraries clash with newly standardized Array.prototype.methods. Sometimes JS Arrays are also used as hash maps, and new prototype methods clash with existing keys used by the application. No current incompatibilities are known or expected.

Gecko: Positive ( Stage 3 TC39 proposal. Gecko has already implemented.

WebKit: Positive ( Stage 3 TC39 proposal. WebKit has already implemented.

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?


Debugged as any other existing Array.prototype method

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


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

In test262: see

Flag name


Requires code in //chrome?


Tracking bug

Estimated milestones

DevTrial on desktop108
DevTrial on Android108

Link to entry on the Chrome Platform Status

This intent message was generated by Chrome Platform Status.

Daniel Bratell

Nov 9, 2022, 11:32:18 AM11/9/22
to Shu-yu Guo, blink-dev



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Philip Jägenstedt

Nov 9, 2022, 11:35:27 AM11/9/22
to Daniel Bratell, Shu-yu Guo, blink-dev

Chris Harrelson

Nov 9, 2022, 11:38:37 AM11/9/22
to Philip Jägenstedt, Daniel Bratell, Shu-yu Guo, blink-dev
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