refactor: extract identifier normalization into a shared utility by KumJungMin · Pull Request #733 · eslint/markdown

KumJungMin · 2026-09-07T12:14:09Z

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What is the purpose of this pull request?

Extract repeated reference identifier normalization logic into a shared utility to reduce duplication while preserving existing comparison behavior.

What changes did you make? (Give an overview)

Added normalizeIdentifier() to src/util.js to combine micromark’s identifier normalization and lowercase conversion in one place.
Updated the following four rules to use the shared utility:
- no-duplicate-definitions
- no-empty-definitions
- no-unused-definitions
- no-reference-like-urls
Added utility tests covering lowercase conversion, trimming leading and trailing whitespace, normalizing consecutive spaces, tabs, and line breaks, and handling empty strings.

Related Issues

fixes #731

Is there anything you'd like reviewers to focus on?

Summary by CodeRabbit

Bug Fixes
- Improved consistency when validating Markdown definitions, footnotes, and reference-style URLs.
- Identifier matching now reliably handles capitalization, spacing, tabs, line breaks, and other normalized whitespace.
- Allow-listed identifiers are normalized consistently, reducing incorrect duplicate, empty, unused, and reference-like URL warnings.
- Matching now preserves the normalized identifier form consistently across validation rules.
Tests
- Added coverage for normalization, casing, trimming, whitespace handling, and empty identifiers.

Fixes eslint#731

coderabbitai · 2026-09-07T12:14:56Z

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Reviewing files that changed from the base of the PR and between 9739c5f and 65c851a.

📒 Files selected for processing (2)

src/util.js
tests/util.test.js

🚧 Files skipped from review as they are similar to previous changes (1)

src/util.js

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📝 Walkthrough

Walkthrough

The change centralizes reference identifier normalization in src/util.js, adds utility tests, and updates four rules to use the shared normalization behavior.

Changes

Reference normalization

Layer / File(s)	Summary
Normalization utility and coverage `src/util.js`, `tests/util.test.js`	The shared utility is organized and tested for casing, trimming, whitespace, line breaks, and empty input.
Rule matching integration `src/rules/no-duplicate-definitions.js`, `src/rules/no-empty-definitions.js`, `src/rules/no-reference-like-urls.js`, `src/rules/no-unused-definitions.js`	The four rules import the shared utility and remove duplicate lowercase transformations.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 65c85

This change centralizes identifier normalization and adds coverage for casing and whitespace behavior. No current merge-blocking risk is identified.

Suggested reviewers: lumirlumir

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes extracting identifier normalization into a shared utility.
Linked Issues check	✅ Passed	The changes address issue `#731` by centralizing identifier normalization, updating all four affected rules, preserving lowercase and whitespace behavior, and adding focused utility tests.
Out of Scope Changes check	✅ Passed	The utility reorganization and added tests directly support the requested refactor. No unrelated code changes are evident.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 6 files.

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lumirlumir

Disclosure: I'm a participant of open source contribution program OSSCA: confirmed.

Thanks for the PR. I’ve left a few stylistic suggestions that we usually follow.

lumirlumir · 2026-09-07T12:35:20Z

 }
+/**


Suggested change

}

/**

}

/**

Non-blocking, but adding a single blank line here would be helpful.

Addressed in 258a910

lumirlumir · 2026-09-07T12:37:05Z

@@ -1,3 +1,5 @@
+import { normalizeIdentifier as micromarkUtilNormalizeIdentifier } from "micromark-util-normalize-identifier";


I think the import statement above needs to be placed below the following fileoverview JSDoc comment, in accordance with our convention:

/** * @fileoverview Utility Library * @author Nicholas C. Zakas */ //------------------------------------------------------------------------------ // Imports //------------------------------------------------------------------------------ import { normalizeIdentifier as micromarkUtilNormalizeIdentifier } from "micromark-util-normalize-identifier"; // ...

Addressed in b4275ed

lumirlumir · 2026-09-07T12:39:05Z

+ * @param {string} identifier The identifier to normalize.
+ * @returns {string} The normalized lowercase identifier.
+ */
+export function normalizeIdentifier(identifier) {


Also, for alphabetical order, it would be helpful to place this function between frontmatterHasTitle and stripHtmlComments.

Addressed in f143dda

lumirlumir

LGTM, thanks!

I’m leaving it open for two more days, just in case anyone else would like to review it, in accordance with our policy.

refactor: extract identifier normalization into a shared utility

9739c5f

Fixes eslint#731

eslint-github-bot Bot added the chore label Sep 7, 2026

eslint-github-bot Bot mentioned this pull request Sep 7, 2026

Change Request: Extract reference identifier normalization into a shared utility #731

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eslintbot added this to Triage Sep 7, 2026

github-project-automation Bot moved this to Needs Triage in Triage Sep 7, 2026

lumirlumir added the accepted label Sep 7, 2026

lumirlumir moved this from Needs Triage to Triaging in Triage Sep 7, 2026

lumirlumir requested changes Sep 7, 2026

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lumirlumir moved this from Triaging to Implementing in Triage Sep 7, 2026

KumJungMin added 4 commits September 7, 2026 22:36

chore: add spacing between utility functions

258a910

chore: place utility import below file overview

b4275ed

chore: sort utility functions alphabetically

f143dda

test: sort utility tests alphabetically

65c851a

KumJungMin requested a review from lumirlumir September 7, 2026 13:43

lumirlumir approved these changes Sep 7, 2026

View reviewed changes

lumirlumir moved this from Implementing to Merge Candidates in Triage Sep 7, 2026

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refactor: extract identifier normalization into a shared utility - #733

refactor: extract identifier normalization into a shared utility#733
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-}
-/**
+}
+/**

		@@ -1,3 +1,5 @@
		import { normalizeIdentifier as micromarkUtilNormalizeIdentifier } from "micromark-util-normalize-identifier";

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Related Issues

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KumJungMin commented Sep 7, 2026 •

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