remark-lint-no-duplicate-definitions

What is remark-lint-no-duplicate-definitions?

The remark-lint-no-duplicate-definitions package is a linting rule for remark-lint that ensures there are no duplicate definitions in Markdown files. This helps maintain clean and error-free Markdown documents by preventing multiple definitions with the same identifier.

What are remark-lint-no-duplicate-definitions's main functionalities?

Detect Duplicate Definitions

This feature detects duplicate definitions in a Markdown file. In the provided code sample, the identifier 'foo' is defined twice, which would trigger a linting error.

```markdown
[foo]: http://example.com
[foo]: http://example.org
```

Other packages similar to remark-lint-no-duplicate-definitions

remark-lint

remark-lint is a plugin for remark that provides a collection of linting rules for Markdown files. It can be extended with additional rules like remark-lint-no-duplicate-definitions. While remark-lint provides a broader set of rules, remark-lint-no-duplicate-definitions focuses specifically on detecting duplicate definitions.

markdownlint

markdownlint is a Node.js style checker and linting tool for Markdown files. It includes a variety of rules to enforce consistent Markdown style, including rules to prevent duplicate definitions. It is similar to remark-lint-no-duplicate-definitions but offers a wider range of linting capabilities.

markdown-it

markdown-it is a Markdown parser that can be extended with plugins to add various functionalities, including linting. While it is primarily a parser, it can be used with plugins to achieve similar functionality to remark-lint-no-duplicate-definitions by detecting and preventing duplicate definitions.

README

remark-lint-no-duplicate-definitions

remark-lint rule to warn when identifiers are defined multiple times.

Contents

• What is this?
• When should I use this?
• Presets
• Install
• Use
• API
  • unified().use(remarkLintNoDuplicateDefinitions)
• Recommendation
• Examples
• Compatibility
• Contribute
• License

What is this?

This package checks that defined identifiers are unique.

When should I use this?

You can use this package to check that definitions are useful.

Presets

This plugin is included in the following presets:

Preset	Options
remark-preset-lint-recommended

Install

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

npm install remark-lint-no-duplicate-definitions

In Deno with esm.sh:

import remarkLintNoDuplicateDefinitions from 'https://esm.sh/remark-lint-no-duplicate-definitions@4'

In browsers with esm.sh:

<script type="module">
  import remarkLintNoDuplicateDefinitions from 'https://esm.sh/remark-lint-no-duplicate-definitions@4?bundle'
</script>

Use

On the API:

import remarkLint from 'remark-lint'
import remarkLintNoDuplicateDefinitions from 'remark-lint-no-duplicate-definitions'
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(remarkLintNoDuplicateDefinitions)
  .use(remarkStringify)
  .process(file)

console.error(reporter(file))

On the CLI:

remark --frail --use remark-lint --use remark-lint-no-duplicate-definitions .

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

 …
 "remarkConfig": {
   "plugins": [
     …
     "remark-lint",
+    "remark-lint-no-duplicate-definitions",
     …
   ]
 }
 …

API

This package exports no identifiers. It exports no additional TypeScript types. The default export is remarkLintNoDuplicateDefinitions.

unified().use(remarkLintNoDuplicateDefinitions)

Warn when identifiers are defined multiple times.

Parameters

There are no options.

Returns

Transform (Transformer from unified).

Recommendation

It’s a mistake when the same identifier is defined multiple times.

Examples

ok.md

In

[mercury]: https://example.com/mercury/
[venus]: https://example.com/venus/

Out

No messages.

not-ok.md

In

[mercury]: https://example.com/mercury/
[mercury]: https://example.com/venus/

Out

2:1-2:38: Unexpected definition with an already defined identifier (`mercury`), expected unique identifiers

gfm.md

In

👉 Note: this example uses GFM (remark-gfm).

Mercury[^mercury].

[^mercury]:
  Mercury is the first planet from the Sun and the smallest in the Solar
  System.

[^mercury]:
  Venus is the second planet from the Sun.

Out

7:1-7:12: Unexpected footnote definition with an already defined identifier (`mercury`), expected unique identifiers

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-duplicate-definitions@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