remark-lint/packages/remark-lint-first-heading-level

remark-lint-first-heading-level

remark-lint rule to warn when the first heading has an unexpected rank.

Contents

• What is this?
• When should I use this?
• Presets
• Install
• Use
• API
  • unified().use(remarkLintFirstHeadingLevel[, config])
• Recommendation
• Examples
• Compatibility
• Contribute
• License

What is this?

This package is a unified (remark) plugin, specifically a remark-lint rule. Lint rules check markdown code style.

When should I use this?

You can use this package to check the heading rank of the first heading.

Presets

This rule is not included in a preset maintained here.

Install

This package is ESM only. In Node.js (version 12.20+, 14.14+, or 16.0+), install with npm:

npm install remark-lint-first-heading-level

In Deno with esm.sh:

import remarkLintFirstHeadingLevel from 'https://esm.sh/remark-lint-first-heading-level@3'

In browsers with esm.sh:

<script type="module">
  import remarkLintFirstHeadingLevel from 'https://esm.sh/remark-lint-first-heading-level@3?bundle'
</script>

Use

On the API:

import {read} from 'to-vfile'
import {reporter} from 'vfile-reporter'
import {remark} from 'remark'
import remarkLint from 'remark-lint'
import remarkLintFirstHeadingLevel from 'remark-lint-first-heading-level'

main()

async function main() {
  const file = await remark()
    .use(remarkLint)
    .use(remarkLintFirstHeadingLevel)
    .process(await read('example.md'))

  console.error(reporter(file))
}

On the CLI:

remark --use remark-lint --use remark-lint-first-heading-level example.md

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

 …
 "remarkConfig": {
   "plugins": [
     …
     "remark-lint",
+    "remark-lint-first-heading-level",
     …
   ]
 }
 …

API

This package exports no identifiers. The default export is remarkLintFirstHeadingLevel.

unified().use(remarkLintFirstHeadingLevel[, config])

This rule supports standard configuration that all remark lint rules accept (such as false to turn it off or [1, options] to configure it).

The following options (default: 1) are accepted:

• number (example 1) — expected rank of first heading

Recommendation

In most cases you’d want to first heading in a markdown document to start at rank 1. In some cases a different rank makes more sense, such as when building a blog and generating the primary heading from frontmatter metadata, in which case a value of 2 can be defined here.

Examples

ok.md

In

# The default is to expect a level one heading

Out

No messages.

ok-html.md

In

<h1>An HTML heading is also seen by this rule.</h1>

Out

No messages.

ok-delayed.md

In

You can use markdown content before the heading.

<div>Or non-heading HTML</div>

<h1>So the first heading, be it HTML or markdown, is checked</h1>

Out

No messages.

not-ok.md

In

## Bravo

Paragraph.

Out

1:1-1:9: First heading level should be `1`

not-ok-html.md

In

<h2>Charlie</h2>

Paragraph.

Out

1:1-1:17: First heading level should be `1`

ok.md

When configured with 2.

In

## Delta

Paragraph.

Out

No messages.

ok-html.md

When configured with 2.

In

<h2>Echo</h2>

Paragraph.

Out

No messages.

not-ok.md

When configured with 2.

In

# Foxtrot

Paragraph.

Out

1:1-1:10: First heading level should be `2`

not-ok-html.md

When configured with 2.

In

<h1>Golf</h1>

Paragraph.

Out

1:1-1:14: First heading level should be `2`

Compatibility

Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

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