micromark-extension-math

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[micromark][] extensions to support math ( $C_L$ ).

* What is this?
* When to use this
* Install
* Use
* API
* math(options?)
* mathHtml(options?)
* HtmlOptions
* Options
* Authoring
* HTML
* CSS
* Syntax
* Types
* Compatibility
* Security
* Related
* Contribute
* License

What is this?

This package contains two extensions that add support for math syntax
in markdown to [micromark][micromark].

As there is no spec for math in markdown, this extension follows how code
(fenced and text) works in Commonmark, but uses dollars.

When to use this

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.

You can use these extensions when you are working with [micromark][micromark]
already.

When you need a syntax tree, you can combine this package with
[mdast-util-math][mdast-util-math].

All these packages are used [remark-math][remark-math], which focusses on
making it easier to transform content by abstracting these internals away.

Install

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

[npm][]:

``sh npm install micromark-extension-math`

In Deno with [esm.sh][esmsh]:

`js import {math, mathHtml} from 'https://esm.sh/micromark-extension-math@3'`

In browsers with [esm.sh][esmsh]:

`html`

`Use`

Say our document example.md contains:

`markdown 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:

`js import fs from 'node:fs/promises' import {micromark} from 'micromark' import {math, mathHtml} from 'micromark-extension-math'

const output = micromark(await fs.readFile('example.md'), { extensions: [math()], htmlExtensions: [mathHtml()] })

console.log(output)`

…now running node example.js yields (abbreviated):

`html

Lift( $\dots$ ) can be determined by Lift Coefficient ( $\dots$ ) like the following equation.


 $\dots$

API

This package exports the identifiers [math][api-math] and [mathHtml][api-math-html]. There is no default export.

The export map supports the [developmentcondition][development]. Runnode --conditions development module.jsto get instrumented dev code. Without this condition, production code is loaded.

`$3`

Create an extension for micromark to enable math syntax.

###### Parameters

* options ([Options][api-options], default: {}) — configuration

###### Returns

Extension for micromark that can be passed in extensions, to enable math syntax ([Extension][micromark-extension]).

`$3`

Create an extension for micromark to support math when serializing to HTML.

> 👉 Note: this uses KaTeX to render math.

###### Parameters

* options ([HtmlOptions][api-html-options], default: {}) — configuration

###### Returns

Extension for micromark that can be passed in htmlExtensions, to support math when serializing to HTML ([HtmlExtension][micromark-html-extension]).

`$3`

Configuration for HTML output (optional).

> 👉 Note: passed to [katex.renderToString][katex-options]. >displayMode is overwritten by this plugin, to falsefor math in text > (inline), andtrue for math in flow (block).

###### Type

`ts type Options = Omit`

`$3`

Configuration (TypeScript type).

###### Fields

* singleDollarTextMath (boolean, default: true) — whether to support math (text, inline) with a single dollar. Single dollars work in Pandoc and many other places, but often interfere with “normal” dollars in text. If you turn this off, you use two or more dollars for text math.

`Authoring`

When authoring markdown with math, keep in mind that math doesn’t work in most places. Notably, GitHub currently has a really weird crappy client-side regex-based thing. But on your own (math-heavy?) site it can be great! You can use code (fenced) with an info string ofmathto improve this, as that works in many places.

`HTML`

Math (flow) does not relate to HTML elements.MathML, which is sort of like SVG but for math, exists but it doesn’t work well and isn’t widely supported. Instead, this uses [KaTeX][], which generates MathML as a fallback but also generates a bunch of divs and spans so math look pretty. The KaTeX result is wrapped in

(for flow, block) and

 (for text,
inline) elements, with two classes:

math and either math-display

or

math-inline

.
When turning markdown into HTML, each line ending in math (text) is turned
into a space.
CSS

The HTML produced by KaTeX requires CSS to render correctly. You should usekatex.csssomewhere on the page where the math is shown to style it properly. At the time of writing, the last version is:

`html`

`Syntax`

Math forms with the following BNF:

`bnf ; Restriction: the number of markers in the closing sequence must be equal ; to the number of markers in the opening sequence. math_text ::= sequence_text 1*byte sequence_text math_flow ::= fence_open ( eol line ) [ eol fence_close ]

; Restriction: not preceded or followed by the marker. sequence_text ::= 1*'$'

fence_open ::= sequence_flow meta ; Restriction: the number of markers in the closing fence sequence must be ; equal to or greater than the number of markers in the opening fence ; sequence. fence_close ::= sequence_flow *space_or_tab sequence_flow ::= 2*'$' ; Restriction: the marker cannot occur inmetameta ::= 1*line

; Character groups for informational purposes. byte ::= 0x00..=0xFFFF eol ::= '\n' | '\r' | '\r\n' line ::= byte - eol`

The above grammar shows that it is not possible to create empty math (text). It is possible to include the sequence marker (dollar) in math (text), by wrapping it in bigger or smaller sequences:

`markdown Include more: $a$$b$ or include less: $$a$b$$.`

It is also possible to include just one marker:

`markdown Include just one: $$ $ $$.`

Sequences are “gready”, in that they cannot be preceded or followed by more markers. To illustrate:

`markdown Not math: $$x$.

Not math: $x$$.

Escapes work, this is math: \$$x$.

Escapes work, this is math: $x$\$.`

Yields:

`html

Not math: $$x$.


Not math: $x$$.

Escapes work, this is math: $….

Escapes work, this is math: …$.


That is because, when turning markdown into HTML, the first and last space,
if both exist and there is also a non-space in the math, are removed.
Line endings, at that stage, are considered as spaces.
As the math (flow) construct occurs in flow, like all flow constructs, it must
be followed by an eol (line ending) or eof (end of file).

The above grammar does not show how indentation of each line is handled. To parse math (flow), letx be the number of space_or_tabcharacters before the opening fence sequence, after interpreting tabs based on how many virtual spaces they represent. Each line of text is then allowed (not required) to be indented with up toxspaces or tabs, which are then ignored as an indent instead of being considered as part of the content. This indent does not affect the closing fence. It can be indented up to a separate 3 real or virtual spaces. A bigger indent makes it part of the content instead of a fence.

The metapart is interpreted as the [string][micromark-content-types] content type. That means that character escapes and character references are allowed.

The optional metapart is ignored: it is not used when parsing or rendering.

`Types`

This package is fully typed with [TypeScript][]. It exports the additional types [HtmlOptions][api-html-options] and [Options][api-options].

`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,micromark-extension-math@^3, compatible with Node.js 16.

This package works with micromark version 3 and later.

`Security`

This package is safe assuming that you trust KaTeX. Any vulnerability in it could open you to a [cross-site scripting (XSS)][xss] attack.

`Related`

* [remark-math][remark-math] — remark (and rehype) plugins to support math * [mdast-util-math][mdast-util-math] — mdast utility to support math

`Contribute`

See [contributing.md in micromark/.github][contributing] for ways to get started. See [support.md`][support] for ways to get help.

This project has a [code of conduct][coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.

License

[build-badge]: https://github.com/micromark/micromark-extension-math/workflows/main/badge.svg

[build]: https://github.com/micromark/micromark-extension-math/actions

[coverage-badge]: https://img.shields.io/codecov/c/github/micromark/micromark-extension-math.svg

[coverage]: https://codecov.io/github/micromark/micromark-extension-math

[downloads-badge]: https://img.shields.io/npm/dm/micromark-extension-math.svg

[downloads]: https://www.npmjs.com/package/micromark-extension-math

[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=micromark-extension-math

[size]: https://bundlejs.com/?q=micromark-extension-math

[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg

[backers-badge]: https://opencollective.com/unified/backers/badge.svg

[collective]: https://opencollective.com/unified

[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg

[chat]: https://github.com/micromark/micromark/discussions

[npm]: https://docs.npmjs.com/cli/install

[esmsh]: https://esm.sh

[license]: license

[author]: https://wooorm.com

[contributing]: https://github.com/micromark/.github/blob/main/contributing.md

[support]: https://github.com/micromark/.github/blob/main/support.md

[coc]: https://github.com/micromark/.github/blob/main/code-of-conduct.md

[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[typescript]: https://www.typescriptlang.org

[development]: https://nodejs.org/api/packages.html#packages_resolving_user_conditions

[micromark]: https://github.com/micromark/micromark

[micromark-content-types]: https://github.com/micromark/micromark#content-types

[micromark-html-extension]: https://github.com/micromark/micromark#htmlextension

[micromark-extension]: https://github.com/micromark/micromark#syntaxextension

[mdast-util-math]: https://github.com/syntax-tree/mdast-util-math

[remark-math]: https://github.com/remarkjs/remark-math

[katex]: https://katex.org

[katex-options]: https://katex.org/docs/options.html

[xss]: https://en.wikipedia.org/wiki/Cross-site_scripting

[api-math]: #mathoptions

[api-math-html]: #mathhtmloptions

[api-options]: #options

[api-html-options]: #htmloptions

micromark-extension-math

micromark-extension-math

Contents

What is this?

When to use this

Install

Use

API

$3

$3

$3

$3

Authoring

HTML

CSS

Syntax

Types

Compatibility

Security

Related

Contribute

License

`Use`

`$3`

`$3`

`$3`

`$3`

`Authoring`

`HTML`

`Syntax`

`Types`

`Compatibility`

`Security`

`Related`

`Contribute`