@pchalin/markdownlint-rule-link-pattern

A markdownlint rule factory for validating link URLs against regex patterns.

Each call to createLinkPatternRule() produces a markdownlint rule that can be independently configured and disabled, and that flags link URLs matching a given regex.

[!IMPORTANT]

This package is published to npm only under the @pchalin scope. The unscoped name is not ours and was once used for malware (GHSA-q3xp-j858-q9xf); never install it.

Install

npm install @pchalin/markdownlint-rule-link-pattern --save-dev

Usage

1. Create rule instances

Create a file (e.g., link-rules.mjs) that defines your rules:

import { createLinkPatternRule } from '@pchalin/markdownlint-rule-link-pattern';

export default [
  createLinkPatternRule('no-http-urls', 'Flag non-HTTPS URLs'),
  createLinkPatternRule('no-example-com', 'Flag example.com links'),
];

2. Register with markdownlint-cli2

In .markdownlint-cli2.yaml:

customRules:
  - ./link-rules.mjs

3. Configure each rule

In .markdownlint.yaml:

no-http-urls:
  pattern: 'http://(?!localhost)'
  message: Use https instead of http.

no-example-com:
  pattern: 'example\.com'
  message: Do not link to example.com.

Config shape

Each rule instance reads its configuration from the markdownlint config under its rule name:

| Property | Type | Required | Description | | ------------ | ------ | -------- | ------------------------------------------------------------------------------- | | pattern | string | yes | Regex pattern to match against link URLs. | | message | string | yes | Error message shown when a link matches. | | skip_regex | string | no | URLs matching this regex are skipped. | | replace | string | no | Replacement text; when set, enables --fix (supports $1, $2 for captures). |

Example with skip_regex

To skip URLs containing template directives (e.g., Hugo {{ }}):

no-example-com:
  pattern: 'example\.com'
  message: Do not link to example.com.
  skip_regex: '\{\{.*\}\}'

Example with replace (auto-fix)

To enable markdownlint --fix for a rule, add replace:

no-http-urls:
  pattern: 'http://'
  message: Use https instead of http.
  replace: 'https://'

no-otel-external-urls:
  pattern: 'https?://(?:www\.)?opentelemetry\.io/'
  message: Use site-relative path.
  replace: '/'

Link types checked

The rule checks all link-like tokens produced by the micromark parser:

• Inline links: [text](url)
• Images: ![alt](url)
• Reference definitions: [label]: url
• Autolinks: <https://...>
• Bare URLs: https://... (GFM extension)

License

Apache-2.0