remark-lint-no-duplicate-defined-urls

3.0.1 verified Fri May 01 auth: no javascript

A remark-lint rule that warns when the same URL is defined multiple times in Markdown definitions. Current stable version is 3.0.1. It is part of the remark-lint ecosystem, focusing on detecting duplicate URLs to prevent mistakes. Unlike other lint rules that check for unused definitions, this targets duplicate URLs. It is ESM-only and requires Node.js 16+. Released as part of the remark-lint monorepo with regular updates.

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module /path/to/remark-lint-no-duplicate-defined-urls/index.js not supported. ↓

cause Using CommonJS require() to load an ESM-only package.

fix

Change to import statement or use dynamic import().

error Unexpected definition with an already defined URL (as `mercury`), expected unique URLs ↓

cause Two definitions in the Markdown file point to the same URL.

fix

Remove or rename one of the duplicate definitions.

error TypeError: remarkLintNoDuplicateDefinedUrls is not a function ↓

cause Using named import { remarkLintNoDuplicateDefinedUrls } instead of default import.

fix

Remove curly braces: import remarkLintNoDuplicateDefinedUrls from ...

Warnings

breaking Package is ESM-only since v3. CommonJS require will fail. ↓

fix Use import syntax instead of require().

deprecated Support for Node.js versions below 16 is dropped as of v3. ↓

fix Upgrade Node.js to v16 or later.

gotcha The package is a default export, not a named export. Using named import will result in undefined. ↓

fix Use default import: import remarkLintNoDuplicateDefinedUrls from 'remark-lint-no-duplicate-defined-urls'

gotcha This rule must be used with remark-lint; it will not work if remark-lint is not in the plugin chain. ↓

fix Ensure .use(remarkLint) is called before this rule.

Install

npm install remark-lint-no-duplicate-defined-urls

yarn add remark-lint-no-duplicate-defined-urls

pnpm add remark-lint-no-duplicate-defined-urls

Imports

remarkLintNoDuplicateDefinedUrls

wrong

const remarkLintNoDuplicateDefinedUrls = require('remark-lint-no-duplicate-defined-urls')

correct

import remarkLintNoDuplicateDefinedUrls from 'remark-lint-no-duplicate-defined-urls'

Package is ESM-only since v3. CommonJS require will fail.

default export

wrong

import { remarkLintNoDuplicateDefinedUrls } from 'remark-lint-no-duplicate-defined-urls'

correct

import remarkLintNoDuplicateDefinedUrls from 'remark-lint-no-duplicate-defined-urls'

The package exports a default function, not a named export.

type import
```
import type { Transformer } from 'unified'
```
Package does not export additional TypeScript types; use unified types if needed.

Quickstart

Set up remark-lint with the no-duplicate-defined-urls rule, parse a Markdown file, and report any lint messages.

import remarkLint from 'remark-lint'
import remarkLintNoDuplicateDefinedUrls from 'remark-lint-no-duplicate-defined-urls'
import remarkParse from 'remark-parse'
import remarkStringify from 'remark-stringify'
import { read } from 'to-vfile'
import { unified } from 'unified'
import { reporter } from 'vfile-reporter'

const file = await read('example.md')

await unified()
  .use(remarkParse)
  .use(remarkLint)
  .use(remarkLintNoDuplicateDefinedUrls)
  .use(remarkStringify)
  .process(file)

console.error(reporter(file))