1566141 - Implement the Nullish Coalescing operator (??) proposal

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement, P3)

Description

[Alexandre Folle de Menezes]

The proposal is currently in Stage 2.

Comment 1

[Steven DeTar [:sdetar]]

This is being set as a P3 like other Stage 2 proposals

Comment 2

[Alexandre Folle de Menezes]

This proposal has been promoted to Stage 3.

Comment 3

[Eric Shepherd [:sheppy]]

When we document this, we need to be sure to update the article on the optional chaining operator to mention using it to establish a non-undefined return value for missing entries.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining

Comment 4

[709922234]

Safari has been implemented

https://webkit.org/blog/9497/release-notes-for-safari-technology-preview-89/

Comment 5

[Tetsuharu OHZEKI [:tetsuharu] (UTC+9)]

Can I take this?

Comment 6

[Jan de Mooij [:jandem]]

(In reply to Tetsuharu OHZEKI [:tetsuharu] [UTC+9] from comment #5)

Can I take this?

I think Yulia is working on this.

Comment 7

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - Nullish coalesce operator tokens

Fake it till you make it

Comment 8

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - Nullish coalesce behavior in bytecode

Depends on D50056

Comment 9

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - add precedence requirement and disallow mixing of logical operators with nullish

coalescing operator

Depends on D50058

Comment 10

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - Add tests for nullish coalescing

Depends on D50204

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/28aa763e7834
Nullish coalesce operator tokens r=jorendorff
https://hg.mozilla.org/integration/autoland/rev/48ef03bd0183
Nullish coalesce behavior in bytecode r=jorendorff
https://hg.mozilla.org/integration/autoland/rev/a32ff28d5f1b
add precedence requirement and disallow mixing of logical operators with nullish r=jorendorff
https://hg.mozilla.org/integration/autoland/rev/812b42c51480
Add tests for nullish coalescing r=jorendorff

Comment 12

[Jan de Mooij [:jandem]]

We should probably send an intent-to-ship to dev-platform..

Comment 13

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/28aa763e7834
https://hg.mozilla.org/mozilla-central/rev/48ef03bd0183
https://hg.mozilla.org/mozilla-central/rev/a32ff28d5f1b
https://hg.mozilla.org/mozilla-central/rev/812b42c51480

Comment 14

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - make interpreter work with JSOP code for coalesce

Comment 15

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - make baseline work with JSOP code for coalesce

Depends on D51638

Comment 16

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - implement nullish coalescence in ion monkey

Depends on D51639

Comment 17

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - rename logicalexpr to shortcircuit where appropriate

Depends on D51640

Comment 18

[Yulia Startsev [:yulia] OOO until July 2026]

Intent to ship has been sent! (a couple of days ago, forgot to update here)

Comment 19

[Yulia Startsev [:yulia] OOO until July 2026]

Attachment: Bug 1566141 - fix fold constants for nullish coalesing

Comment 20

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9b150dd56999
make interpreter work with JSOP code for coalesce r=jorendorff,jandem
https://hg.mozilla.org/integration/autoland/rev/2a8c35575189
make baseline work with JSOP code for coalesce r=jorendorff,jandem
https://hg.mozilla.org/integration/autoland/rev/ddc6fa7e24f2
implement nullish coalescence in ion monkey r=jandem

Comment 21

[Oana Pop-Rus]

https://hg.mozilla.org/mozilla-central/rev/9b150dd56999
https://hg.mozilla.org/mozilla-central/rev/2a8c35575189
https://hg.mozilla.org/mozilla-central/rev/ddc6fa7e24f2

Comment 22

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/14a04a7ccab4
fix fold constants for nullish coalesing r=jorendorff

Comment 23

[Stefan Hindli [:stefan_hindli]]

https://hg.mozilla.org/mozilla-central/rev/14a04a7ccab4

Comment 24

[Julien G]

Documentation written here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator
(other pages updated such as: https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining & https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence )