remark-lint rule to warn when top-level headings are used multiple times.
Contents
What is this?
This package checks that top-level headings are unique.
When should I use this?
You can use this package to check heading structure.
Presets
This plugin is included in the following presets:
Install
This package is ESM only. In Node.js (version 16+), 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@4'
In browsers with esm.sh:
<script type="module">
import remarkLintNoMultipleToplevelHeadings from 'https://esm.sh/remark-lint-no-multiple-toplevel-headings@4?bundle'
</script>
Use
On the API:
import remarkLint from 'remark-lint'
import remarkLintNoMultipleToplevelHeadings from 'remark-lint-no-multiple-toplevel-headings'
import remarkParse from 'remark-parse'
import remarkStringify from 'remark-stringify'
import {read} from 'to-vfile'
import {unified} from 'unified'
import {reporter} from 'vfile-reporter'
const file = await read('example.md')
await unified()
.use(remarkParse)
.use(remarkLint)
.use(remarkLintNoMultipleToplevelHeadings)
.use(remarkStringify)
.process(file)
console.error(reporter(file))
On the CLI:
remark --frail --use remark-lint --use remark-lint-no-multiple-toplevel-headings .
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. It exports the TypeScript types Depth and Options. The default export is remarkLintNoMultipleToplevelHeadings.
Warn when top-level headings are used multiple times.
Parameters
options (Options, default: 1) — configuration
Returns
Transform (Transformer from unified).
Depth
Depth (TypeScript type).
Type
type Depth = 1 | 2 | 3 | 4 | 5 | 6
Options
Configuration (TypeScript type).
Type
type Options = Depth
Recommendation
Documents should almost always have one main heading, which is typically a heading with a rank of 1.
Examples
ok.md
In
# Mercury
## Venus
Out
No messages.
not-ok.md
In
# Venus
# Mercury
Out
3:1-3:10: Unexpected duplicate toplevel heading, exected a single heading with rank `1`
not-ok.md
When configured with 2.
In
## Venus
## Mercury
Out
3:1-3:11: Unexpected duplicate toplevel heading, exected a single heading with rank `2`
html.md
In
Venus <b>and</b> mercury.
<h1>Earth</h1>
<h1>Mars</h1>
Out
5:1-5:14: Unexpected duplicate toplevel heading, exected a single heading with rank `1`
mdx.mdx
In
👉 Note: this example uses MDX (remark-mdx).
Venus <b>and</b> mercury.
<h1>Earth</h1>
<h1>Mars</h1>
Out
4:1-4:14: Unexpected duplicate toplevel heading, exected a single heading with rank `1`
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-no-multiple-toplevel-headings@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