Intent to Ship: Array and TypedArray findLast and findLastIndex

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Shu-yu Guo

Oct 7, 2021, 1:22:05 PM10/7/21
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This is a Stage 3 TC39 proposal that adds the methods findLast and findLastIndex to Array.prototype and the various TypedArray.prototypes. These methods are the "from the end" versions of find and findIndex.

Blink component


TAG review

TAG review status

Not applicable


Interoperability and Compatibility

Adding any new methods to Array.prototype runs the risk of web incompatibility due to breaking old libraries. Rollout will need to be monitored.

Gecko: Positive This is Stage 3 in TC39

WebKit: Positive This is Stage 3 in TC39

Web developers: Positive (


It is a new prototype method, so can be debugged like any other prototype method.

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

Yes, in test262

Flag name


Requires code in //chrome?


Tracking bug

Estimated milestones

DevTrial on desktop94
DevTrial on android94
DevTrial on Webview94

Link to entry on the Chrome Platform Status

This intent message was generated by Chrome Platform Status.

Chris Harrelson

Oct 7, 2021, 8:40:17 PM10/7/21
to Shu-yu Guo, blink-dev

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Yoav Weiss

Oct 8, 2021, 12:19:17 AM10/8/21
to Chris Harrelson, Shu-yu Guo, blink-dev

Daniel Bratell

Oct 8, 2021, 2:48:51 AM10/8/21
to Yoav Weiss, Chris Harrelson, Shu-yu Guo, blink-dev

LGTM3  (I sent an LGTM1 yesterday but as a direct mail, doh)

Joe Medley

Oct 8, 2021, 10:00:51 AM10/8/21
to Shu-yu Guo, blink-dev

In which version are you wanting to ship?

Joe Medley | Technical Writer, Chrome DevRel | | 816-678-7195
If an API's not documented it doesn't exist.

On Thu, Oct 7, 2021 at 10:22 AM 'Shu-yu Guo' via blink-dev <> wrote:

Shu-yu Guo

Oct 8, 2021, 11:56:21 AM10/8/21
to Joe Medley, blink-dev
Hi Joe,

I will land the flag flip early next week, which would put this on-by-default in M97.

Joe Medley

Oct 8, 2021, 12:24:16 PM10/8/21
to Shu-yu Guo, blink-dev
Thanks. Can you please add that to the Chrome Status entry? Open it for editing, click "Edit all fields", then scroll all the way to the bottom.

Joe Medley | Technical Writer, Chrome DevRel | | 816-678-7195
If an API's not documented it doesn't exist.

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