unified-lint-rule

unified helper to help make lint rules.

What is this?

This package is a helper that makes it a bit easier to create linting rules.

When should I use this?

You can use this package when you want to make custom lint rules.

Install

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

npm install unified-lint-rule

In Deno with esm.sh:

import {lintRule} from 'https://esm.sh/unified-lint-rule@3'

In browsers with esm.sh:

<script type="module">
  import {lintRule} from 'https://esm.sh/unified-lint-rule@3?bundle'
</script>

Use

import {lintRule} from 'unified-lint-rule'

const remarkLintFileExtension = lintRule(
  'remark-lint:file-extension',
  function (tree, file, options) {
    const ext = file.extname
    const option = options || 'md'

    if (ext && ext.slice(1) !== option) {
      file.message('Incorrect extension: use `' + option + '`')
    }
  }
)

export default remarkLintFileExtension

API

This package exports the identifier lintRule. It exports the TypeScript types Label, Meta, Next, and Severity. There is no default export.

`lintRule(meta, rule)`

Create a plugin.

Parameters

meta (Meta or string) — info or origin
rule (Rule) — rule

Returns

Plugin (Plugin from unified).

`Label`

Severity label (TypeScript type); 'off': 0, 'on' and warn: 1, 'error': 2.

Type

type Label = 'error' | 'on' | 'off' | 'warn'

`Meta`

Rule metadata (TypeScript type).

Fields

origin (string) — name of the lint rule
url (string, optional) — link to documentation

`Next`

Callback passed to rules (TypeScript type).

If the signature of a rule accepts a fourth argument, the rule may perform asynchronous operations, and must call it.

Parameters

error (Error, optional) — fatal error to stop linting

Returns

Nothing (undefined).

`Rule`

Rule (TypeScript type).

Parameters

tree (Node from unist) — tree
file (VFile) — file
options (unknown, optional) — parameter

Returns

Nothing (Promise<undefined> or undefined).

`Severity`

Severity number (TypeScript type); 0: 'off', 1: 'on' and warn, 2: 'error'.

Type

type Severity = 0 | 1 | 2

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, unified-lint-rule@3, 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.

Package detail