remark-lint rule to warn on duplicate headings
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[remark-lint][github-remark-lint] rule to warn when the same text is used in multiple headings.
* What is this?
* When should I use this?
* Presets
* Install
* Use
* API
* unified().use(remarkLintNoDuplicateHeadings)
* Recommendation
* Examples
* Compatibility
* Contribute
* License
This package checks that headings are unique.
You can use this package to check that headings are unique.
This plugin is included in the following presets:
| Preset | Options |
| - | - |
| remark-preset-lint-markdown-style-guide | |
This package is [ESM only][github-gist-esm].
In Node.js (version 16+),
install with [npm][npm-install]:
``sh`
npm install remark-lint-no-duplicate-headings
In Deno with [esm.sh][esm-sh]:
`js`
import remarkLintNoDuplicateHeadings from 'https://esm.sh/remark-lint-no-duplicate-headings@4'
In browsers with [esm.sh][esm-sh]:
`html`
On the API:
`js
import remarkLint from 'remark-lint'
import remarkLintNoDuplicateHeadings from 'remark-lint-no-duplicate-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(remarkLintNoDuplicateHeadings)
.use(remarkStringify)
.process(file)
console.error(reporter(file))
`
On the CLI:
`sh`
remark --frail --use remark-lint --use remark-lint-no-duplicate-headings .
On the CLI in a config file (here a package.json):
`diff`
…
"remarkConfig": {
"plugins": [
…
"remark-lint",
+ "remark-lint-no-duplicate-headings",
…
]
}
…
This package exports no identifiers.
It exports no additional [TypeScript][typescript] types.
The default export is
[remarkLintNoDuplicateHeadings][api-remark-lint-no-duplicate-headings].
Warn when the same text is used in multiple headings.
###### Parameters
There are no options.
###### Returns
Transform ([Transformer from unified][github-unified-transformer]).
Headings having unique text helps screen reader users,
who typically use “jump to heading” features to navigate within a page,
which reads headings out loud.
It also helps because often headings receive automatic unique IDs,
and when the same heading text is used,
they are suffixed with a number based on where they are positioned in the
document,
which makes linking to them prone to changes.
##### ok.md
###### In
`markdownMercury
###### Out
No messages.
#####
###### In
markdown
Mercury
Mercury
Mercury
`###### Out
text
3:1-3:11: Unexpected heading with equivalent text, expected unique headings
5:1-5:43: Unexpected heading with equivalent text, expected unique headings
`#####
###### In
> 👉 Note: this example uses
> MDX ([
][github-remark-mdx]).`mdx
Mercury
Mercury
`###### Out
text
2:1-2:17: Unexpected heading with equivalent text, expected unique headings
`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,
,
compatible with Node.js 16.Contribute
See [
contributing.md][github-dotfiles-contributing] in [remarkjs/.github][github-dotfiles-health] for ways
to get started.
See [support.md`][github-dotfiles-support] for ways to get help.This project has a [code of conduct][github-dotfiles-coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.
[MIT][file-license] © [Titus Wormer][author]
[api-remark-lint-no-duplicate-headings]: #unifieduseremarklintnoduplicateheadings
[author]: https://wooorm.com
[badge-build-image]: https://github.com/remarkjs/remark-lint/workflows/main/badge.svg
[badge-build-url]: https://github.com/remarkjs/remark-lint/actions
[badge-chat-image]: https://img.shields.io/badge/chat-discussions-success.svg
[badge-chat-url]: https://github.com/remarkjs/remark/discussions
[badge-coverage-image]: https://img.shields.io/codecov/c/github/remarkjs/remark-lint.svg
[badge-coverage-url]: https://codecov.io/github/remarkjs/remark-lint
[badge-downloads-image]: https://img.shields.io/npm/dm/remark-lint-no-duplicate-headings.svg
[badge-downloads-url]: https://www.npmjs.com/package/remark-lint-no-duplicate-headings
[badge-funding-backers-image]: https://opencollective.com/unified/backers/badge.svg
[badge-funding-sponsors-image]: https://opencollective.com/unified/sponsors/badge.svg
[badge-funding-url]: https://opencollective.com/unified
[badge-size-image]: https://img.shields.io/bundlejs/size/remark-lint-no-duplicate-headings
[badge-size-url]: https://bundlejs.com/?q=remark-lint-no-duplicate-headings
[esm-sh]: https://esm.sh
[file-license]: https://github.com/remarkjs/remark-lint/blob/main/license
[github-dotfiles-coc]: https://github.com/remarkjs/.github/blob/main/code-of-conduct.md
[github-dotfiles-contributing]: https://github.com/remarkjs/.github/blob/main/contributing.md
[github-dotfiles-health]: https://github.com/remarkjs/.github
[github-dotfiles-support]: https://github.com/remarkjs/.github/blob/main/support.md
[github-gist-esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
[github-remark-lint]: https://github.com/remarkjs/remark-lint
[github-remark-mdx]: https://mdxjs.com/packages/remark-mdx/
[github-unified-transformer]: https://github.com/unifiedjs/unified#transformer
[npm-install]: https://docs.npmjs.com/cli/install
[typescript]: https://www.typescriptlang.org