1222547 - Remove Array generics

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Tooru Fujisawa [:arai]]

Array generics are non-standard SpiderMonkey extension and they should be removed.
  * Array.concat
  * Array.every
  * Array.filter
  * Array.forEach
  * Array.indexOf
  * Array.join
  * Array.lastIndexOf
  * Array.map
  * Array.pop
  * Array.push
  * Array.reduce
  * Array.reduceRight
  * Array.reverse
  * Array.shift
  * Array.slice
  * Array.some
  * Array.sort
  * Array.splice
  * Array.unshift

Comment 1

[Kohei]

Posted the site compatibility doc: https://www.fxsitecompat.com/en-US/docs/2015/array-string-generics-will-be-removed/

Comment 2

[:Ms2ger (he/him; ⌚ UTC+1/+2)]

We should probably add telemetry and then warnings.

Comment 3

[Tooru Fujisawa [:arai]]

Some of them should be used frequently (like, Array.slice, Array.forEach), and some other won't be.
searching AMO repository might give us some data.

not sure if it worth getting telemetry for each function tho.

Comment 5

[:aceman]

What about Array.from() and Array.isArray() ? Does this bug mean anything starting with Array. or only the specific listed methods?

Comment 6

[Tooru Fujisawa [:arai]]

Array.from and Array.isArray (and Array.of) are in spec.

this bug is about non-standard static methods listed in comment #0.

Comment 7

[Tom S. (please needinfo tschuster)]

Sadly some of those functions still have quite a few uses inside Firefox. If we added a warning those might go away, but would also annoy other developers.

Comment 8

[David Bruant]

(In reply to Tom Schuster [:evilpie] from comment #7)

Sadly some of those functions still have quite a few uses inside Firefox. If we added a warning those might go away, but would also annoy other developers.

Which other developers are using these functions?

Comment 9

[Tom S. (please needinfo tschuster)]

BMO uses the generic Array.forEach, luckily they seem to provide a polyfill. The code comes from http://dean.edwards.name/base/forEach.js.

Comment 11

[Tom S. (please needinfo tschuster)]

Some the measured values are still extremely high, especially slice and forEach. On the other hand I haven't seen any fallout from this change on Nightly. Maybe there a lot of instances where websites already have some fallback/polyfill for other browsers.

Comment 12

[Tom S. (please needinfo tschuster)]

Jason what do you think?

Comment 13

[Jason Orendorff [:jorendorff]]

Let's try it!

Comment 14

[Tom S. (please needinfo tschuster)]

Attachment: Bug 1222547 - Remove JavaScript Array generics. r?jandem

Comment 15

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/311d8c50d88b
Remove JavaScript Array generics. r=jandem

Comment 16

[Cristian Brindusan [:cbrindusan]]

Backed out changeset 311d8c50d88b (Bug 1222547) for spidermonkey bustages on JSFunction.h:568.

Backout: https://hg.mozilla.org/integration/autoland/rev/7d4b2dc29c17629de982dd50b1b76244ae943574

Push that started the failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&resultStatus=pending%2Crunning%2Csuccess%2Ctestfailed%2Cbusted%2Cexception&revision=311d8c50d88b1603a4e861eb50a8aeec12aebae5&selectedJob=268661949

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=268661949&repo=autoland&lineNumber=9651

Comment 17

[Tom S. (please needinfo tschuster)]

Attachment: Bug 1222547 - Remove telemetry. r?jandem

Comment 18

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ee339b902006
Remove JavaScript Array generics. r=jandem
https://hg.mozilla.org/integration/autoland/rev/004f5255d2fc
Remove telemetry. r=jandem

Comment 19

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/ee339b902006
https://hg.mozilla.org/mozilla-central/rev/004f5255d2fc

Comment 20

[Kohei]

Posted site compatibility note: https://www.fxsitecompat.dev/en-CA/docs/2019/non-standard-array-generics-have-been-removed/

Comment 21

[Alexandru Ionescu (needinfo me) [:alexandrui]]

== Change summary for alert #23288 (as of Mon, 30 Sep 2019 16:54:49 GMT) ==

Improvements:

0.49% Base Content JS macosx1014-64-shippable opt 4,080,544.00 -> 4,060,677.33
0.39% Base Content JS linux64 opt 4,071,397.33 -> 4,055,626.67
0.38% Base Content JS linux64-qr opt 4,071,344.00 -> 4,055,760.00
0.38% Base Content JS linux64-shippable opt 4,071,317.33 -> 4,055,680.00
0.38% Base Content JS linux64-shippable-qr opt 4,071,317.33 -> 4,055,653.33
0.38% Base Content JS windows10-64 opt 4,138,698.67 -> 4,122,928.00
0.38% Base Content JS windows10-64-qr opt 4,138,672.00 -> 4,122,901.33
0.38% Base Content JS windows10-64-shippable opt 4,138,698.67 -> 4,122,981.33
0.38% Base Content JS windows10-64-shippable-qr opt 4,138,752.00 -> 4,122,901.33
0.33% Base Content JS windows7-32 opt 3,239,056.00 -> 3,228,528.00
0.32% Base Content JS windows7-32-shippable opt 3,239,045.33 -> 3,228,528.00

For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=23288

Comment 22

[Florian Scholz (Open Web Docs)]

Removed section about array generics on https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
Announced removal on Fx71 for developers https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/71#JavaScript