remark-lint-no-unused-definitions

4.0.2 verified Fri May 01 auth: no javascript

A remark-lint rule that warns when definitions are not referenced in the document. Current version 4.0.2, part of the remark-lint monorepo, released as ESM-only. Differentiators: catches dead code (unused link/image/footnote definitions) to keep Markdown clean. Works with remark-gfm for footnotes. No options. Part of the recommended preset.

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module ... not supported. ↓

cause CJS require() used with ESM-only package.

fix

Use import syntax or dynamic import().

error TypeError: plugin.use is not a function ↓

cause Calling unified().use() with the default imported function incorrectly (e.g., as object instead of function).

fix

Ensure you are passing the default export directly: .use(remarkLintNoUnusedDefinitions)

error Cannot find module 'remark-lint' ↓

cause Missing peer dependency 'remark-lint'.

fix

Install remark-lint: npm install remark-lint

Warnings

breaking Package is ESM-only starting from v4.0.0. Node.js 12 no longer supported. ↓

fix Use import syntax instead of require(); upgrade Node.js to 16+.

deprecated The 'remark-lint' package is required but may be deprecated in future in favor of '@mysticatea/remark-lint' or similar. ↓

fix Ensure remark-lint is still maintained; consider alternative lint integrations.

gotcha The rule does not check references before definitions; it only warns if a definition has zero references. ↓

fix Combine with remark-lint-no-undefined-references to catch both sides.

gotcha Footnotes (GFM) are checked case-insensitively for references; a footnote reference 'mercury' matches definition '[^Mercury]'. ↓

fix Be aware of case-insensitive matching when using GFM footnotes.

Install

npm install remark-lint-no-unused-definitions

yarn add remark-lint-no-unused-definitions

pnpm add remark-lint-no-unused-definitions

Imports

remarkLintNoUnusedDefinitions

wrong

const remarkLintNoUnusedDefinitions = require('remark-lint-no-unused-definitions')

correct

import remarkLintNoUnusedDefinitions from 'remark-lint-no-unused-definitions'

ESM-only since v4; CommonJS require will fail.

default

wrong

import { remarkLintNoUnusedDefinitions } from 'remark-lint-no-unused-definitions'

correct

import remarkLintNoUnusedDefinitions from 'remark-lint-no-unused-definitions'

The package exports a single default export; named import does not exist.

remarkLintNoUnusedDefinitions as a unified plugin
```
.use(remarkLintNoUnusedDefinitions)
```
No extra options; just pass the function to .use().

Quickstart

Shows how to use the rule: lints a Markdown string with an unused definition, outputting an error message.

import { unified } from 'unified';
import remarkParse from 'remark-parse';
import remarkStringify from 'remark-stringify';
import remarkLint from 'remark-lint';
import remarkLintNoUnusedDefinitions from 'remark-lint-no-unused-definitions';
import { reporter } from 'vfile-reporter';

const file = await unified()
  .use(remarkParse)
  .use(remarkLint)
  .use(remarkLintNoUnusedDefinitions)
  .use(remarkStringify)
  .process('[mercury]: https://example.com/mercury/');

console.error(reporter(file));
// 1:1-1:40: Unexpected unused definition, expected no definition or one or more references to `mercury`