Registry / testing / unified-lint-rule

unified-lint-rule

library3.0.1jsnpmunverified

A helper package for the unified ecosystem that simplifies creating linting rules for processors like remark, retext, and rehype. Version 3.0.1 is the current stable release (ESM-only, requires Node.js 16+). It provides a `lintRule` function that takes metadata and a rule callback, handling plugin registration, error messages via VFile, and severity levels. Key differentiators: reduces boilerplate for unified lint rule authors, supports both sync and async rules, includes TypeScript types, and is part of the official remark-lint family.

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npm install unified-lint-rule

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INSTALL

IMPORT

SIG · UNIFIED-LINT-RULE

unified-lint-rule

testingjavascriptv3.0.1

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

lintRule

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

✗ const { lintRule } = require('unified-lint-rule')

Package is ESM-only since v3; require() throws ERR_REQUIRE_ESM.

Creates a custom rule that checks file extension, showing the minimal API to build a lint rule.

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 // Usage with unified: // import { unified } from 'unified' // import remarkParse from 'remark-parse' // import remarkStringify from 'remark-stringify' // import remarkLintFileExtension from './my-lint-rule.js' // const file = await unified().use(remarkParse).use(remarkLintFileExtension, 'md').process('') // console.log(file.messages)

Debug

Known issues

breakingESM-only: Node.js 16+ required. CommonJS require() will fail with ERR_REQUIRE_ESM.

fix

Switch to ES module syntax (import) and ensure package.json has "type": "module" or use .mjs extension.

affects: >=3.0.0

gotchaThe rule function's fourth parameter is the `Next` callback for async rules; omitting it makes the rule synchronous. If you need async, you must accept a fourth parameter and call it when done.

fix

Define rule with exactly 3 parameters for sync, or 4 parameters (including `Next`) for async, and always call next() to avoid hanging.

affects: >=1.0.0

gotchaOptions are passed as the third argument to the rule function. If the rule is configured with no options, the value is `undefined`. Default handling is manual.

fix

Check for undefined options and provide defaults explicitly (e.g., `const opts = options || 'md'`).

affects: >=1.0.0

deprecatedIn unified-lint-rule v2, the `lintRule` function returned a plugin with a different signature. In v3, the return is a standard unified plugin.

fix

Ensure your unified version is compatible (>=10). No code changes needed if using unified's .use().

affects: >=3.0.0

Errors

Common errors & fixes

ERR_REQUIRE_ESM

Using CommonJS require() on an ESM-only package.

fix

Convert to ES module syntax: use `import { lintRule } from 'unified-lint-rule'` and set "type": "module" in package.json.

TypeError: (intermediate value).message is not a function

Calling `file.message()` incorrectly (e.g., passing options as first argument without string).

fix

Ensure the first argument to `file.message` is a string describing the lint error: `file.message('Incorrect extension: use `' + option + '`')`.

Error: Expected a `origin` string

Passing invalid metadata to `lintRule` (e.g., missing colon in origin or non-string).

fix

Provide a properly formatted origin string like 'remark-lint:my-rule' (must contain a colon).

Upgrade

Version history

3.0.1latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

9 hits · last 30 days

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Resources

githubhttps://github.com/remarkjs/remark-lint.git#main ↗

packagehttps://www.npmjs.com/package/unified-lint-rule ↗