remark-lint-heading-style

remark-lint rule to warn when headings violate a given style.

Contents

• What is this?
• When should I use this?
• Presets
• Install
• Use
• API
  • unified().use(remarkLintHeadingStyle[, options])
  • Options
  • Style
• Recommendation
• Fix
• Examples
• Compatibility
• Contribute
• License

What is this?

This package checks the style of headings.

When should I use this?

You can use this package to check that the style of headings is consistent.

Presets

This plugin is included in the following presets:

Preset	Options
remark-preset-lint-consistent	'consistent'
remark-preset-lint-markdown-style-guide	'atx'

Install

This package is ESM only. In Node.js (version 16+), install with npm:

1npm install remark-lint-heading-style

In Deno with esm.sh:

1import remarkLintHeadingStyle from 'https://esm.sh/remark-lint-heading-style@4'

In browsers with esm.sh:

1<script type="module">
2  import remarkLintHeadingStyle from 'https://esm.sh/remark-lint-heading-style@4?bundle'
3</script>

Use

On the API:

1import remarkLint from 'remark-lint'
2import remarkLintHeadingStyle from 'remark-lint-heading-style'
3import remarkParse from 'remark-parse'
4import remarkStringify from 'remark-stringify'
5import {read} from 'to-vfile'
6import {unified} from 'unified'
7import {reporter} from 'vfile-reporter'
8
9const file = await read('example.md')
10
11await unified()
12  .use(remarkParse)
13  .use(remarkLint)
14  .use(remarkLintHeadingStyle)
15  .use(remarkStringify)
16  .process(file)
17
18console.error(reporter(file))

On the CLI:

1remark --frail --use remark-lint --use remark-lint-heading-style .

On the CLI in a config file (here a package.json):

1 …
2 "remarkConfig": {
3   "plugins": [
4     …
5     "remark-lint",
6+    "remark-lint-heading-style",
7     …
8   ]
9 }
10 …

API

This package exports no identifiers. It exports the TypeScript types Options and Style. The default export is remarkLintHeadingStyle.

unified().use(remarkLintHeadingStyle[, options])

Warn when headings violate a given style.

Parameters

• options (Options, default: 'consistent') — preferred style or whether to detect the first style and warn for further differences

Returns

Transform (Transformer from unified).

Options

Configuration (TypeScript type).

Type

1type Options = Style | 'consistent'

Style

Style (TypeScript type).

Type

1type Style = 'atx' | 'atx-closed' | 'setext'

Recommendation

Setext headings are limited in that they can only construct headings with a rank of one and two. They do allow multiple lines of content where ATX only allows one line. The number of used markers in their underline does not matter, leading to either:

• 1 marker (Hello\n-), which is the bare minimum, and for rank 2 headings looks suspiciously like an empty list item
• using as many markers as the content (Hello\n-----), which is hard to maintain and diff
• an arbitrary number (Hello\n---), which for rank 2 headings looks suspiciously like a thematic break

Setext headings are also uncommon. Using a sequence of hashes at the end of ATX headings is even more uncommon. Due to this, it’s recommended to use ATX headings, without closing hashes.

Fix

remark-stringify formats headings as ATX by default. The other styles can be configured with setext: true or closeAtx: true.

Examples

ok.md

When configured with 'atx'.

In

1# Mercury
2
3## Venus
4
5### Earth

Out

No messages.

ok.md

When configured with 'atx-closed'.

In

1# Mercury ##
2
3## Venus ##
4
5### Earth ###

Out

No messages.

ok.md

When configured with 'setext'.

In

1Mercury
2=======
3
4Venus
5-----
6
7### Earth

Out

No messages.

not-ok.md

In

1Mercury
2=======
3
4## Venus
5
6### Earth ###

Out

14:1-4:9: Unexpected ATX heading, expected setext
26:1-6:14: Unexpected ATX (closed) heading, expected setext

not-ok.md

When configured with '🌍'.

Out

11:1: Unexpected value `🌍` for `options`, expected `'atx'`, `'atx-closed'`, `'setext'`, or `'consistent'`

Compatibility

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line, remark-lint-heading-style@4, compatible with Node.js 16.

Contribute

See contributing.md in remarkjs/.github for ways to get started. See support.md for ways to get help.

This project has a code of conduct. By interacting with this repository, organization, or community you agree to abide by its terms.

License

MIT © Titus Wormer