feat(formatter): add option to split binary expressions before operators #6159

bavalpey · 2025-05-28T21:01:51Z

Summary

Adds a new option to the javascript formatter, operator_linebreak that configures whether linebreaks for binary expressions should occur before or after the binary operator.

Prettier has implemented this: prettier/prettier#7111

Test Plan

I wrote tests for this that are on par with the other tests for formatting options.
It tests that when the option is enabled, long lines break before the binary operator instead of after.
I based it off of similar formatting options tests, each of which had only one unit test and weren't really testing edge cases. I presume that this is sufficient.

Additional Information

There are nearly 0 logic changes required for this.

To see how it works:
For the javascript file

const VERY_LONG_CONDITION_1234123412341234123412341234 = false;

if (VERY_LONG_CONDITION_1234123412341234123412341234 && VERY_LONG_CONDITION_1234123412341234123412341234 && VERY_LONG_CONDITION_1234123412341234123412341234 && VERY_LONG_CONDITION_1234123412341234123412341234) {
  console.log("DONE")
}

running with the option --javascript-formatter-operator-linebreak=before produces

  ✖ Formatter would have printed the following content:
  
    1  1 │   const VERY_LONG_CONDITION_1234123412341234123412341234 = false;
    2  2 │   
    3    │ - if·(VERY_LONG_CONDITION_1234123412341234123412341234·&&·VERY_LONG_CONDITION_1234123412341234123412341234·&&·VERY_LONG_CONDITION_1234123412341234123412341234·&&·VERY_LONG_CONDITION_1234123412341234123412341234)·{
    4    │ - ··console.log("DONE")
       3 │ + if·(
       4 │ + → VERY_LONG_CONDITION_1234123412341234123412341234
       5 │ + → &&·VERY_LONG_CONDITION_1234123412341234123412341234
       6 │ + → &&·VERY_LONG_CONDITION_1234123412341234123412341234
       7 │ + → &&·VERY_LONG_CONDITION_1234123412341234123412341234
       8 │ + )·{
       9 │ + → console.log("DONE");
    5 10 │   }
    6    │ - 
    7 11 │

codspeed-hq · 2025-05-29T05:57:46Z

CodSpeed Performance Report

Merging #6159 will degrade performances by 61.19%

_{Comparing bavalpey:break-before-binary-ops (0dfeee9) with next (275cc8b)¹}

🎉 Hooray! `codspeed-rust` just leveled up to 3.0.3!

A heads-up, this is a breaking change and it might affect your current performance baseline a bit. But here's the exciting part - it's packed with new, cool features and promises improved result stability 🥳!
Curious about what's new? Visit our releases page to delve into all the awesome details about this new version.

Summary

⚡ 1 improvements
❌ 3 regressions
✅ 110 untouched benchmarks
🆕 1 new benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	`BASE`	`HEAD`	Change
❌	`js_analyzer[index_3894593175024091846.js]`	49.4 ms	53 ms	-6.75%
❌	`js_analyzer[parser_13571644119461115204.ts]`	79.4 ms	85.3 ms	-6.94%
🆕	`module_graph[@next/font/google/index.d.ts]`	N/A	290.2 ms	N/A
⚡	`deserialize_from_json_str[package.json]`	1,038.3 µs	930.8 µs	+11.55%
❌	`deserialize_from_json_str[tsconfig.json]`	218 µs	561.8 µs	-61.19%

No successful run was found on next (90c5d6b) during the generation of this report, so f00af73 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

bavalpey · 2025-05-30T14:01:30Z

I'm not understanding some of the checks that are failing, like the codegen and documentation.

Is there a step I am supposed to do to fix the codegen? (test output: https://github.com/biomejs/biome/actions/runs/15312085380/job/43092346301?pr=6159)

ematipico · 2025-05-30T15:33:04Z

I'm not understanding some of the checks that are failing, like the codegen and documentation.

Is there a step I am supposed to do to fix the codegen? (test output: biomejs/biome/actions/runs/15312085380/job/43092346301?pr=6159)

We have a command that takes care of the codegen: just gen-all. For this particular case, you can run just gen-bindings. Since you updated the configuration, the schema must be updated.

Here the section of the contribution guide: https://github.com/biomejs/biome/blob/main/CONTRIBUTING.md#checks

bavalpey · 2025-06-07T22:11:37Z

I'm not understanding some of the checks that are failing, like the codegen and documentation.
Is there a step I am supposed to do to fix the codegen? (test output: biomejs/biome/actions/runs/15312085380/job/43092346301?pr=6159)

We have a command that takes care of the codegen: just gen-all. For this particular case, you can run just gen-bindings. Since you updated the configuration, the schema must be updated.

Here the section of the contribution guide: https://github.com/biomejs/biome/blob/main/CONTRIBUTING.md#checks

Thanks. I've followed the steps and run this now.

I wasn't sure if I needed to add a changelog for this, as the instructions for changelogs seemed to be directed towards PRs that were adding a new minor release? Surely you would bundle something like this with other changes for a minor release?

Let me know if there's anything additional I need to do to get this in. I'm very keen on having this option in.

bavalpey · 2025-06-08T14:43:03Z

Hmm.
I've no idea why benchmarks are now timing out? All I did was run the command to update the schema.

It worked before I did this: https://github.com/biomejs/biome/actions/runs/15348620153

Now it's failing, saying the action timed out: https://github.com/biomejs/biome/actions/runs/15512128393/job/43686071399?pr=6159

ematipico

Thank you @bavalpey

The PR looks good. I am going to block it because we're close to ship v2 and we don't want to ship more features than we already have. We will merge it and ship in v1

The failures in CI aren't a concern, don't worry. You did splendid.

PointSingularity · 2025-06-22T08:30:53Z

Is this considered for the next release?

ematipico · 2025-06-22T10:36:56Z

Is this considered for the next release?

Yes, for the next minor. No ETA

PointSingularity · 2025-07-08T14:09:27Z

Hoping this one comes in the next patch 🤞
(need to migrate the whole codebase from prettier, but don't want to submit a 500 file change PR twice)

ematipico · 2025-07-08T16:19:07Z

Oh, damn, that's on us 😢 apologies! We should have added it to next minor, and forgot about it. Let me create a milestone now so I won't forget.

In the meantime, @bavalpey, can you please point this PR to the next branch?

bavalpey · 2025-07-08T18:09:35Z

In the meantime, @bavalpey, can you please point this PR to the next branch?

Done. But there's now conflicts. What's the protocol for resolving these? Does a maintainer generally edit?

ematipico · 2025-07-08T18:55:06Z

If you're in a position to resolve the conflicts, that would be great. Otherwise we do it when we can

ematipico · 2025-07-22T22:32:27Z

Hey @bavalpey , will you be able to resolve the conflicts?

bavalpey · 2025-07-22T22:40:56Z

Hey @bavalpey , will you be able to resolve the conflicts?

Sure let me take a look. Not sure how involved they are.

changeset-bot · 2025-07-22T22:59:52Z

🦋 Changeset detected

Latest commit: 0dfeee9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 14 packages

Name	Type
@biomejs/biome	Minor
@biomejs/cli-win32-x64	Minor
@biomejs/cli-win32-arm64	Minor
@biomejs/cli-darwin-x64	Minor
@biomejs/cli-darwin-arm64	Minor
@biomejs/cli-linux-x64	Minor
@biomejs/cli-linux-arm64	Minor
@biomejs/cli-linux-x64-musl	Minor
@biomejs/cli-linux-arm64-musl	Minor
@biomejs/wasm-web	Minor
@biomejs/wasm-bundler	Minor
@biomejs/wasm-nodejs	Minor
@biomejs/backend-jsonrpc	Patch
@biomejs/js-api	Major

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bavalpey · 2025-07-22T23:01:24Z

Hey @bavalpey , will you be able to resolve the conflicts?

Done

ematipico · 2025-07-22T23:10:26Z

Thank you. Can you please add a changeset too? That's missing and we require it

bavalpey · 2025-07-23T00:57:46Z

Thank you. Can you please add a changeset too? That's missing and we require it

Done. Let me know if it looks sufficient.

bavalpey · 2025-07-23T03:53:01Z

Hmm.. Not sure why the PR I did just to fix the merge conflict would cause an unrelated test to break...
Or a performance regression, for that matter.

siketyan · 2025-07-23T04:01:57Z

@bavalpey You can just update the snapshots to make the failing tests pass. You can ignore the performance regression too

bavalpey · 2025-07-23T04:05:01Z

@bavalpey You can just update the snapshots to make the failing tests pass. You can ignore the performance regression too

Oh, right. New snapshots would've been added since merge, and I forgot to update them. Thanks!

.changeset/mighty-seals-dance.md

7Hua · 2025-07-31T11:43:46Z

"javascript": { "formatter": { "indentStyle": "space", "indentWidth": 4, "bracketSpacing": false, "quoteStyle": "single", "trailingCommas": "none", "arrowParentheses": "asNeeded", "operator-linebreak": "before", } },。Why am I still unable to use operator-linebreak in biome, and it prompts "Found an unknown key operator-linebreak"?

ematipico · 2025-07-31T12:01:17Z

Because it hasn't been released yet. It will be available in the next minor

…ors (#6159) Co-authored-by: bavalpey <bavalpey@users.noreply.github.com> Co-authored-by: Emanuele Stoppa <my.burning@gmail.com> Co-authored-by: ematipico <602478+ematipico@users.noreply.github.com> Co-authored-by: PointSingularity <56246797+PointSingularity@users.noreply.github.com> Co-authored-by: siketyan <12772118+siketyan@users.noreply.github.com>

bavalpey added 2 commits May 28, 2025 14:58

Make line break before binary operators instead of after

4112cee

Make operator linebreak an option

f67c923

github-actions bot added A-CLI Area: CLI A-Project Area: project A-Formatter Area: formatter L-JavaScript Language: JavaScript and super languages labels May 28, 2025

bavalpey changed the title ~~feat~~ feat(formatter): Add option to split binary expressions before operators May 28, 2025

bavalpey changed the title ~~feat(formatter): Add option to split binary expressions before operators~~ feat(formatter): add option to split binary expressions before operators May 28, 2025

bavalpey added 4 commits May 28, 2025 16:14

Remove leaked comment

9135b71

Fix doc comment stating improper default

2e80014

Add operator_linebreak_resolved

16758e7

Add test for operator_linebreak option

4717483

bavalpey and others added 3 commits May 30, 2025 09:03

Fix formatting issue

fa1a4dd

Merge branch 'main' into break-before-binary-ops

79476c9

Update snapshots for new cli option

288b0a4

Run just gen-bindings to update schema

999d271

ematipico requested changes Jun 9, 2025

View reviewed changes

arendjr added this to the Biome 2.1 milestone Jun 23, 2025

ematipico modified the milestones: Biome 2.1, Biome v2.2 Jul 8, 2025

bavalpey changed the base branch from main to next July 8, 2025 18:08

Merge branch 'next' into break-before-binary-ops

92fe899

bavalpey requested a review from ematipico July 22, 2025 23:01

Add changeset

cc2a3a1

chore: Update snapshots

d951a3f

ematipico approved these changes Jul 23, 2025

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ematipico added 3 commits July 23, 2025 07:34

Update .changeset/mighty-seals-dance.md

cbc0a81

Update .changeset/mighty-seals-dance.md

eb06b92

Update .changeset/mighty-seals-dance.md

0dfeee9

ematipico merged commit f02a296 into biomejs:next Jul 26, 2025
27 of 28 checks passed

github-actions bot mentioned this pull request Aug 13, 2025

ci: release #7157

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feat(formatter): add option to split binary expressions before operators #6159

feat(formatter): add option to split binary expressions before operators #6159

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Summary

Test Plan

Additional Information

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CodSpeed Performance Report

Merging #6159 will degrade performances by 61.19%

🎉 Hooray! codspeed-rust just leveled up to 3.0.3!

Summary

Benchmarks breakdown

Footnotes

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