Markdown

This page documents 17 rules from the current dependency versions and repository configuration. Each entry includes effective severity, scope, upstream description, common messages, and incorrect/correct examples.

Rules from third-party presets (17 rules)

markdown/fenced-code-language

Checks the corresponding code constraint. Upstream description: Require languages for fenced code blocks

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Missing code block language.; Code block language "{{lang}}" is not allowed.
• Example type: Direct code example for a third-party preset rule

Incorrect:

```
const ready = true;
```

Correct:

```js
const ready = true;
```

markdown/heading-increment

Checks the corresponding code constraint. Upstream description: Enforce heading levels increment by one

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Heading level skipped from {{fromLevel}} to {{toLevel}}.
• Example type: Direct code example for a third-party preset rule

Incorrect:

# Guide

### Setup

Correct:

# Guide

## Setup

markdown/no-duplicate-definitions

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow duplicate definitions

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Unexpected duplicate definition '{{ identifier }}' (label: '{{ label }}') found. First defined at line {{ firstLine }} (label: '{{ firstLabel }}').; Unexpected duplicate footnote definition '{{ identifier }}' (label: '{{ label }}') found. First defined at line {{ firstLine }} (label: '{{ firstLabel }}').
• Example type: Direct code example for a third-party preset rule

Incorrect:

[docs]: https://example.com/a
[docs]: https://example.com/b

Correct:

[docs]: https://example.com/a
[api]: https://example.com/b

markdown/no-empty-definitions

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow empty definitions

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Unexpected empty definition '{{ identifier }}' (label: '{{ label }}') found.; Unexpected empty footnote definition '{{ identifier }}' (label: '{{ label }}') found.
• Example type: Direct code example for a third-party preset rule

Incorrect:

[docs]: #

Correct:

[Guide][docs]

[docs]: https://example.com/docs

markdown/no-empty-images

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow empty images

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Unexpected empty image found.
• Example type: Direct code example for a third-party preset rule

Incorrect:

![Fast logo]()

Correct:

![Fast logo](/logo.png)

markdown/no-empty-links

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow empty links

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Unexpected empty link found.
• Example type: Direct code example for a third-party preset rule

Incorrect:

[Fast]()

Correct:

[Fast](https://example.com)

markdown/no-invalid-label-refs

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow invalid label references

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Label reference '{{label}}' is invalid due to white space between [ and ].
• Example type: Direct code example for a third-party preset rule

Incorrect:

[Guide][ ]

Correct:

[Guide][guide]

[guide]: /guide

markdown/no-missing-atx-heading-space

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow headings without a space after the hash characters

• Effective severity and scope: error: Markdown
• Autofix: Supported; review semantics and the diff before applying
• Rule source: Official documentation
• Common messages: Missing space {{position}} hash(es) on ATX style heading.
• Example type: Direct code example for a third-party preset rule

Incorrect:

##Setup

Correct:

## Setup

markdown/no-missing-label-refs

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow missing label references

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Label reference '{{label}}' not found.
• Example type: Direct code example for a third-party preset rule

Incorrect:

[Guide][missing]

Correct:

[Guide][guide]

[guide]: /guide

markdown/no-missing-link-fragments

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow link fragments that do not reference valid headings

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Link fragment '#{{fragment}}' does not reference a heading or anchor in this document.
• Example type: Direct code example for a third-party preset rule

Incorrect:

[Install](#missing)

Correct:

## Install

[Install](#install)

markdown/no-multiple-h1

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow multiple H1 headings in the same document

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Unexpected additional H1 heading found.
• Example type: Direct code example for a third-party preset rule

Incorrect:

# Guide

# API

Correct:

# Guide

## API

markdown/no-reference-like-urls

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow URLs that match defined reference identifiers

• Effective severity and scope: error: Markdown
• Autofix: Supported; review semantics and the diff before applying
• Rule source: Official documentation
• Common messages: Unexpected resource {{type}} ('{{prefix}}[text](url)') with URL that matches a definition identifier. Use '[text][id]' syntax instead.
• Example type: Direct code example for a third-party preset rule

Incorrect:

[docs]: /guide

[Guide](docs)

Correct:

[docs]: /guide

[Guide][docs]

markdown/no-reversed-media-syntax

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow reversed link and image syntax

• Effective severity and scope: error: Markdown
• Autofix: Supported; review semantics and the diff before applying
• Rule source: Official documentation
• Common messages: Unexpected reversed syntax found. Use [label](URL) syntax instead.
• Example type: Direct code example for a third-party preset rule

Incorrect:

(Guide)[/guide]

Correct:

[Guide](/guide)

markdown/no-space-in-emphasis

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow spaces around emphasis markers

• Effective severity and scope: error: Markdown
• Autofix: Supported; review semantics and the diff before applying
• Rule source: Official documentation
• Common messages: Unexpected space around emphasis marker.
• Example type: Direct code example for a third-party preset rule

Incorrect:

** emphasized **

Correct:

**emphasized**

markdown/no-unused-definitions

Disallows unsafe, invalid, or misleading constructs. Upstream description: Disallow unused definitions

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Unexpected unused definition '{{ identifier }}' (label: '{{ label }}') found.; Unexpected unused footnote definition '{{ identifier }}' (label: '{{ label }}') found.
• Example type: Direct code example for a third-party preset rule

Incorrect:

Text only.

[docs]: /guide

Correct:

[Guide][docs]

[docs]: /guide

markdown/require-alt-text

Requires the declarations, properties, or structures specified by this rule. Upstream description: Require alternative text for images

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Alternative text for image is required.
• Example type: Direct code example for a third-party preset rule

Incorrect:

![](/chart.png)

Correct:

![Request volume chart](/chart.png)

markdown/table-column-count

Checks the corresponding code constraint. Upstream description: Disallow data rows in a GitHub Flavored Markdown table from having more cells than the header row

• Effective severity and scope: error: Markdown
• Autofix: Unsupported or not declared upstream
• Rule source: Official documentation
• Common messages: Table column count mismatch (Expected: {{expectedCells}}, Actual: {{actualCells}}), extra data starting here will be ignored.; Table column count mismatch (Expected: {{expectedCells}}, Actual: {{actualCells}}), row might be missing data.
• Example type: Direct code example for a third-party preset rule

Incorrect:

| Name | Value |
| --- | --- |
| A | 1 | extra |

Correct:

| Name | Value |
| --- | --- |
| A | 1 |