remark-lint/packages/remark-lint-no-multiple-toplevel-headings

remark-lint-no-multiple-toplevel-headings

remark-lint rule to warn when more than one top level heading is used.

Contents

• What is this?
• When should I use this?
• Presets
• Install
• Use
• API
  • unified().use(remarkLintNoMultipleToplevelHeadings[, 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 that no more than one top level heading is used.

Presets

This rule is included in the following presets:

Preset	Setting
remark-preset-lint-markdown-style-guide

Install

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

npm install remark-lint-no-multiple-toplevel-headings

In Deno with esm.sh:

import remarkLintNoMultipleToplevelHeadings from 'https://esm.sh/remark-lint-no-multiple-toplevel-headings@3'

In browsers with esm.sh:

<script type="module">
  import remarkLintNoMultipleToplevelHeadings from 'https://esm.sh/remark-lint-no-multiple-toplevel-headings@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 remarkLintNoMultipleToplevelHeadings from 'remark-lint-no-multiple-toplevel-headings'

main()

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

  console.error(reporter(file))
}

On the CLI:

remark --use remark-lint --use remark-lint-no-multiple-toplevel-headings example.md

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

 …
 "remarkConfig": {
   "plugins": [
     …
     "remark-lint",
+    "remark-lint-no-multiple-toplevel-headings",
     …
   ]
 }
 …

API

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

unified().use(remarkLintNoMultipleToplevelHeadings[, 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) — assumed top level heading rank

Recommendation

Documents should almost always have one main heading, which is typically a heading with a rank of 1.

Examples

ok.md

When configured with 1.

In

# Foo

## Bar

Out

No messages.

not-ok.md

When configured with 1.

In

# Foo

# Bar

Out

3:1-3:6: Don’t use multiple top level headings (1:1)

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