Mdast-comment-marker NPM

mdast-comment-marker

mdast utility to parse comment markers.

What is this?

This package is a utility that tries to parse a structured marker from a comment.

When should I use this?

Comments are a hidden part of markdown, so they can be used as processing instructions. For example, this utility is used in remark-lint to control whether lint rules are turned on or ignored, and by mdast-zone to replace sections between two markers.

Install

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

npm install mdast-comment-marker

In Deno with esm.sh:

import {commentMarker} from 'https://esm.sh/mdast-comment-marker@3'

In browsers with esm.sh:

<script type="module">
  import {commentMarker} from 'https://esm.sh/mdast-comment-marker@3?bundle'
</script>

Use

import {commentMarker} from 'mdast-comment-marker'

console.log(commentMarker({type: 'html', value: '<!--foo-->'}));

console.log(commentMarker({
  type: 'html',
  value: '<!--foo bar baz=12.4 qux="test test" quux=\'false\'-->'
}));

console.log(commentMarker({type: 'html', value: '<!doctype html>'}));

// Also supports MDX expressions:
console.log(commentMarker({
  type: 'mdxFlowExpression',
  value: '/* lint disable heading-style */'
}));

Yields:

{
  name: 'foo',
  attributes: '',
  parameters: {},
  node: { type: 'html', value: '<!--foo-->' }
}
{
  name: 'foo',
  attributes: `bar baz=12.4 qux="test test" quux='false'`,
  parameters: { bar: true, baz: 12.4, qux: 'test test', quux: false },
  node: {
    type: 'html',
    value: `<!--foo bar baz=12.4 qux="test test" quux='false'-->`
  }
}
undefined
{
  name: 'lint',
  attributes: 'disable heading-style',
  parameters: { disable: true, 'heading-style': true },
  node: {
    type: 'mdxFlowExpression',
    value: '/* lint disable heading-style */'
  }
}

API

This package exports the identifier commentMarker. There is no default export.

`commentMarker(value)`

Parse a comment marker.

Parameters

value (unknown) — thing to parse, typically Node

Returns

Info (Marker) when applicable or undefined.

`Marker`

Comment marker (TypeScript type).

Properties

name (string) — name of marker
attributes (string) — value after name
parameters (MarkerParameters) — parsed attributes
node (Node) — reference to given node

`MarkerParameters`

Parameters (TypeScript type).

type

type MarkerParameters = Record<string, MarkerParameterValue>

`MarkerParameterValue`

Value (TypeScript type).

If it looks like a number (to JavaScript), it’s cast as number. The strings true and false are turned into their corresponding booleans. The empty string is also considered the true boolean.

type

type MarkerParameterValue = number | string | boolean

Types

This package is fully typed with TypeScript. This package exports the types Marker, MarkerParameters, and MarkerParameterValue

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, mdast-comment-marker@^3, compatible with Node.js 16.

Security

Use of mdast-comment-marker does not involve hast, user content, or change the tree, so there are no openings for cross-site scripting (XSS) attacks.