refactor(browser): Make comments emitted by codegen stick to the statement below them

[allansson]

Description

In idiomatic code, comments usually stick to the statements below them. Our codegen was emitting a new line between a comment and the statement below it. This PR changes the behavior to make the comment stick to the element below it.

The API is configurable to opt-out of the "stickiness".

Before:

After:

How to Test

1. Export a script
2. The "Generated by..." comment should stick to the import statements below it.

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have commented on my code, particularly in hard-to-understand areas.

Related PR(s)/Issue(s)

Related to #1037

[allansson]

Self-review

[allansson]

The header is arguably one place where we'd want there to be a space after.

[Copilot]

Pull request overview

This pull request refactors the code generation system to make comments "stick" to the statements below them by removing the blank line that was previously inserted. The change updates the NewLine type from a string union to an object with optional boolean or 'never' properties, allowing more granular control over newline behavior.

Changes:

• Modified the NewLine type from a string union to an object with optional before and after properties
• Updated spacing utility functions to work with the new object-based NewLine type
• Changed the default behavior for comments to use { after: 'never' }, preventing newlines from being added after them
• Updated 38 snapshot test files to reflect the removal of blank lines after comments

Reviewed changes

Copilot reviewed 34 out of 35 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/codegen/estree/typescript-estree.d.ts	Refactored NewLine type from string union to object with before/after properties
src/codegen/browser/formatting/spacing.ts	Updated spacing functions to use new object-based NewLine type
src/codegen/browser/formatting/formatter.ts	Updated applySpacing to check object properties instead of string values
src/codegen/browser/code/comment.ts	Added default newLine parameter with { after: 'never' } to prevent spacing
src/codegen/browser/__snapshots__/**/*.ts (38 files)	Removed blank lines between generated comments and subsequent code

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[Copilot]

This should be { after: true } not { after: false }. The spaceAround function is supposed to add spacing before the first element and after the last element, but this line sets after to false, which would prevent adding a newline after the last element. This is inconsistent with the function's intended behavior and with line 89 which correctly sets before to true.

[Copilot]

The merging logic doesn't preserve target properties when newLine doesn't specify them. For example, if target has before: 'never' and newLine is { after: true } (with before undefined), the result will have before=undefined, losing the 'never' constraint. The logic should preserve target values when newLine doesn't explicitly override them. Consider using: const before = newLine.before !== undefined ? (target.before === 'never' ? 'never' : newLine.before) : target.before and similarly for after. This ensures that 'never' constraints are always respected, and target values are preserved when not explicitly overridden.

[Llandy3d]

I agree that for the header I would keep the space after, also it would be great to confirm that this doesn't break the checking we do in dashboards 🤔

[allansson]

I agree that for the header I would keep the space after, also it would be great to confirm that this doesn't break the checking we do in dashboards 🤔

@Llandy3d I've added back the space after the header. We're not emitting any other type of comment right now, so we don't need to worry about anything getting messed up in the dashboards.

I did this PR to make the output nicer in this contributor PR.