unified

Project: syntax-tree/mdast-util-math

Package: mdast-util-math@2.0.1

  1. Dependents: 0
  2. mdast extension to parse and serialize math
  1. markdown 151
  2. util 147
  3. utility 143
  4. unist 133
  5. mdast 88
  6. mdast-util 31
  7. markup 19
  8. math 6
  9. latex 6
  10. tex 5
  11. katex 4

mdast-util-math

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mdast extensions to parse and serialize math ($C_L$).

Contents

What is this?

This package contains extensions that add support for math to mdast-util-from-markdown and mdast-util-to-markdown.

When to use this

These tools are all rather low-level. In most cases, you’d want to use remark-math with remark instead.

This project is useful when you want to support math in markdown. Extending markdown with a syntax extension makes the markdown less portable. LaTeX equations are also quite hard. But this mechanism works well when you want authors, that have some LaTeX experience, to be able to embed rich diagrams of math in scientific text.

When working with mdast-util-from-markdown, you must combine this package with micromark-extension-math.

This utility adds fields on nodes so that the utility responsible for turning mdast (markdown) nodes into hast (HTML) nodes, mdast-util-to-hast, turns text (inline) math nodes into <span class="math math-inline">…</span> and flow (block) math nodes into <div class="math math-display">…</div>.

Install

This package is ESM only. In Node.js (version 12.20+, 14.14+, or 16.0+), install with npm:

npm install mdast-util-math

In Deno with esm.sh:

import {mathFromMarkdown, mathToMarkdown} from 'https://esm.sh/mdast-util-math@2'

In browsers with esm.sh:

<script type="module">
  import {mathFromMarkdown, mathToMarkdown} from 'https://esm.sh/mdast-util-math@2?bundle'
</script>

Use

Say our document example.md contains:

Lift($L$) can be determined by Lift Coefficient ($C_L$) like the following equation.

$$
L = \frac{1}{2} \rho v^2 S C_L
$$

…and our module example.js looks as follows:

import fs from 'node:fs/promises'
import {fromMarkdown} from 'mdast-util-from-markdown'
import {toMarkdown} from 'mdast-util-to-markdown'
import {math} from 'micromark-extension-math'
import {mathFromMarkdown, mathToMarkdown} from 'mdast-util-math'

const doc = await fs.readFile('example.md')

const tree = fromMarkdown(doc, {
  extensions: [math()],
  mdastExtensions: [mathFromMarkdown()]
})

console.log(tree)

const out = toMarkdown(tree, {extensions: [mathToMarkdown()]})

console.log(out)

…now running node example.js yields (positional info and data removed for brevity):

{
  type: 'root',
  children: [
    {
      type: 'paragraph',
      children: [
        {type: 'text', value: 'Lift('},
        {type: 'inlineMath', value: 'L', data: {/* … */}},
        {type: 'text', value: ') can be determined by Lift Coefficient ('},
        {type: 'inlineMath', e: 'C_L', data: {/* … */}},
        {type: 'text', value: ') like the following equation.'}
      ]
    },
    {type: 'math', meta: null, value: 'L = \\frac{1}{2} \\rho v^2 S C_L', data: {/* … */}}
  ]
}
Lift($L$) can be determined by Lift Coefficient ($C_L$) like the following equation.

$$
L = \frac{1}{2} \rho v^2 S C_L
$$

API

This package exports the identifiers mathFromMarkdown and mathToMarkdown. There is no default export.

mathFromMarkdown()

Function that can be called to get an extension for mdast-util-from-markdown.

mathToMarkdown(options?)

Function that can be called to get an extension for mdast-util-to-markdown.

options

Configuration (optional).

options.singleDollarTextMath

Whether to support text math (inline) with a single dollar (boolean, default: true). Single dollars work in Pandoc and many other places, but often interfere with “normal” dollars in text.

HTML

This plugin integrates with mdast-util-to-hast. When mdast is turned into hast the math nodes are turned into <span class="math math-inline">…</span> and <div class="math math-display">…</div> elements.

Syntax tree

The following interfaces are added to mdast by this utility.

Nodes

Math

interface Math <: Literal {
  type: "code"
  meta: string?
}

Math (Literal) represents a block of math, such as LaTeX mathematical expressions.

Math can be used where flow content is expected. Its content is represented by its value field.

This node relates to the phrasing content concept InlineMath.

A meta field can be present. It represents custom information relating to the node.

For example, the following markdown:

$$
L = \frac{1}{2} \rho v^2 S C_L
$$

Yields:

{
  type: 'math',
  meta: null,
  value: 'L = \\frac{1}{2} \\rho v^2 S C_L',
  data: {/* … */}
}

InlineMath

interface InlineMath <: Literal {
  type: "inlineMath"
}

InlineMath (Literal) represents a fragment of computer code, such as a file name, computer program, or anything a computer could parse.

InlineMath can be used where phrasing content is expected. Its content is represented by its value field.

This node relates to the flow content concept Math.

For example, the following markdown:

$L$

Yields:

{type: 'inlineMath', value: 'L', data: {/* … */}}

Content model

FlowContent (math)

type FlowContentMath = Math | FlowContent

PhrasingContent (math)

type PhrasingMath = InlineMath | PhrasingContent

Types

This package is fully typed with TypeScript. It exports the additional types Math, InlineMath, and ToOptions.

It also registers the node types with @types/mdast. If you’re working with the syntax tree, make sure to import this utility somewhere in your types, as that registers the new node types in the tree.

/**
 * @typedef {import('mdast-util-math')}
 */

import {visit} from 'unist-util-visit'

/** @type {import('mdast').Root} */
const tree = getMdastNodeSomeHow()

visit(tree, (node) => {
  // `node` can now be one of the nodes for math.
})

Compatibility

Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

This plugin works with mdast-util-from-markdown version 1+ and mdast-util-to-markdown version 1+.

Contribute

See contributing.md in syntax-tree/.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